SOUND RECORDER- REPRODUCER SET · Changes in force C1, C2, C4, C6, C7, and C8 Change No. 8 TM 11-2583A C8 HEADQUARTERS DEPARTMENT OF THE ARMY Washington, D.C.,5 November 1973 SOUND

TM 11-2583A

DEPARTMENT OF THE ARMY TECHNICAL MANUAL

SOUND RECORDER-

REPRODUCER SETAN/TNH-2A

This copy is reprint which includes current pages from changes 1-2-4-6-7-8

DEPARTMENT OF THE ARMY • JANUARY 1956

W A R N I N GDANGEROUS VOLTAGES EXIST IN THIS EQUIPMENT

Be careful when working on the B+ plate andscreen circuits and all power supply circuits,

or on the 115-volt ac line connections.

DON’T TAKE CHANCES!

Changes in force C1, C2, C4, C6, C7, and C8

Change

No. 8

TM 11-2583AC 8

HEADQUARTERSDEPARTMENT OF THE ARMY

Washington, D.C., 5 November 1973

SOUND RECORDER-REPRODUCER SETSAN/TNH-2A AND AN/TNH-2B

TM 11-2583A, 30 January 1956. is changed as follows:Page 1. Paragraph 1.1 is superseded as fol-

lows:

1.1. Indexes of Publicationsa. DA Pam 310-4. Refer to the latest issue of

DA Pam 310-4 to determine whether there arenew editions, changes, or additional publica-tions pertaining to the equipment.

b. DA Pam 920-7. Refer to DA Pam 310-7 todetermine whether there are modification workorders (MWO's) pertaining to the equipment.Paragraph 2 is superseded as follows:

2. Forms and Recordsa. Reports of Maintenance and Unsatisfac-

tory Equipment. Maintenance forms, records,and reports which are to be used by mainte-nance personnel at all maintenance levels arelisted in and prescribed by TM 38-750.

b. Report of Packaging and Handling Deficien-cies. Fill out and forward DD Form 6 (Reportof Packaging and Handling Deficiencies) asprescribed in AR 700-58 (Army)/NAVSUP Pub378 (Navy)/AFR 71-4 (Air Force)/and MCOP4030.29 (Marine Corps).

c. Discrepancy in Shipment Report (DISREP)(SF 361). Fill out and forward Discrepancyin Shipment Report (DISREP) (SF 361) as pre-scribed in AR 55-38 (Army )/NAVSUP Pub 459(Navy)/AFM 75-34 (Air Force)/and MCO P4610.19(Marine Corps).Paragraph 2.1 is added after paragraph 2.2.1. Reporting of Equipment Publication

ImprovementsThe Reporting of errors, omissions, and recom-mendations for improving this publication bythe individual user is encouraged. Reportsshould be submitted on DA Form 2028 (Recom-mended Changes to Publications) and forwardeddirect to Commander, US Army ElectronicsCommand, ATTN: AMSEL-MA-C, Fort Mon-mouth, NJ 07703.

Page 2, paragraph 5. Change heading to read“Table of Components and Dimensions of SoundRecorder-Reproducer Set AN/TNH-2A.” Para-graph 5.1. Change heading to read “Table of Com-ponents and Dimensions of Sound Recorder-Reproducer Set AN/TNH-2B.”

Page 3. Paragraphs 5.2 and 5.3 are added afterparagraph 5.1.

1

5.2. Items Comprising Operable Sound Recorder-Reproducer SetsAN/TNH-2A (FSN 5835-503-1512) and AN/TNH-2B (FSN 5835-543-0079)

FSNUsable

oncode

5830-537-7755

5830-537-7756

5835-543-0080

5995-889-1304

5995-161-2572

5995-296-1607

5965-296-9910

5965-296-3117

5835-54343081

5835-543-0282

5820-5664668

5835-393-1983

5835-583-12965835-537-7812

5935-187-0716

5835-509-8442

QTY

1

1

1

1

1

1

1

1

1

1

1

1

11

1

Nomenclature, part No., and mfr code

NOTEThe part number is followed by the applicable 5 digit Federal supplycode for manufacturers (FSCM) identified in SB 708-42 and used toidentify manufacturer, distributor, or Government agency, etc.

NOTEIn usable on code column, number 1 refers to Recorder ReproducerSet, Sound, AN/TNH-2A; number 2 refers to Recorder ReproducerSet, Sound, AN/TNH-2B.

Amplifier, Audio Frequency AM-124WU, 5W power output, 115v, 60 Hz, singleph. 1 channel input, 50,000 ohm impedance, SC-DL-282750, 80063 (Installedin equip)

Amplifier Power Supply AM-1251 /TNH-2A; provides amplification and erasesignal for motor board assembly, 19 in. lg x 7 in. h x 14 in. w o/a, SC-DL-282772,80063 (Installed in equip)

Amplifier Power Supply AM-1634 /TNH-2B, AF amplifier, 8W output, 600 ohmsimpedance, Power Supply 1.6 amp 5v, 115v 60 Hz, single ph. 7 in. x 14 x 19 in.,o/a, SM-D-282801, 80063 (Installed in equip)

Cable Assembly, Power, Electrical CX-1206/U. 2 No. 18 AWG cond, approx6 ft 9 in. lg o/a, SC-D-25128, 80063

Cable Assembly, Power Electrical CX-120WU, 2 No. 18 AWG cond, approx 10ft lg o/a, SC-D-25128, 80063

Cable Assembly, Radio Frequency CG-1368/U, 1 cond RG-58/U, one end PJ-055B, sec end Cannon XL-3-12,SM-C-28.3011, 80063

Headset, Electrical H-l04/G, H-104A/G, Dynamic type, 300 ohms nonimpe-dance connected in parallel earphone, 2 in. dia x 1 in. d o/a, GA 5 ft lg withplug-in term

Microphone, Dynamic M-65/U, 150 ohms impedance, 100 to 10,000 Hz freqrange (Not mounted)

Recorder Reproducer Subassembly, Sound RD-149/TNH-2B, c/o l ea tapetransport mechanism. recording head, reproducing head, 2 motors, singleph, 19 in. lg x 15-3/4 in. h x 6-1/2 in. deep (Installed in equip)

Reel, Sound, Recording Tape: STD 10-1/2 in. reel, American Moulded ProductsRETMA 10-1/2 in. (Installed in equip)

Splicer, Magnetic Recording Tape, steel, 1-1/2 in. w 2-3/8 in. x 5-7/8 in, o/adia. Robbins Ind part No. TS4

Tape, Leader Timing, Recorder Reproducer, paper, 3-3/4 in. lg x 1/4 in. w o/a.43-1.5,76381

Tape, Sound Recording, 1/4 in. w, 2400 ft lg. Fed type TAT-A-FT-2400-250-PATape, Splicing, Recorder Reproducer, plastic base, white, 0.50 in. w x 0.002

in. thk, 41-l/2L, 76381AMPLIFIER POWER SUPPLY

AM-1634 /TNH-2Bconnector, Plug, Electrical, 10 male cont. 10 amps, 730v, P310-FHT, 71785

(Installed in equip)RECORDER REPRODUCER SUBASSEMBLY SOUND

RD-146/TNH-2AAND

RECORDER REPRODUCER SUBASSEMBLY SOUNDRD-149/TNH-2B

Holder, Reel, used to mount reels of tape, TR+05, 30040 (Installed in equip)

1,2

1

2

1,2

1,2

1,2

1,2

1,2

2

1,2

1,2

1,2

1,21,2

2

5.3. Expendable Consumable ItemsA list of expendable consumable items requiredfor operation appears in table 1-1.

Table 1-1. Expendable Consumable Supplies and Materials

The supplies and material listed in this table are required for operation of this equipment and are authorized to be requisitioned bySB 700-50. The FSN for the applicable unit of issue required can be found in appropriate supply catalogs. The FSCM is used as anelement in item identification to designate manufacturer or distributor or Government agency, etc., and is identified in SB 708-42.

Item Description Ref No.and FSC

FSCM1 Tape, Sound Recording, 1/4 in. w, 2400 ft lg. TAT-A-FT-2400-250-PA, 81348 5835

Page 89. Appendix III is superseded as fol-lows:

APPENDIX IllBASIC ISSUE ITEMS LIST

Section I. INTRODUCTION

1. ScopeThis appendix lists basic issue items requiredby the crew/operator for installation, opera-tion, and maintenance of Sound Recorder-Re-producer Sets AN/TNH-2A and AN/TNH-2B.

2. GeneralThis basic issue items list is a list, in alphabe-tical sequence, of items which are furnishedwith, and which must be turned in with the enditem.

3. Explanation of ColumnsThe following provides an explanation of columnsfound in the tabular listings:

a. Illustration. This column is divided as fol-lows

(1) Figure number. Indicates the figure num-ber of the illustration in which the item isshown.

(2) ltem number. Not applicable.b. Federal Stock Number. Indicates the Fed-

eral stock number assigned to the item and willbe used for requisitioning purposes.

c. Part Number. Indicates the primary n um-ber used by the manufacturer (individual, com-pany, firm, corporation, or Government ac-tivity), which controls the design and charac-teristics of the item by means of its engineeringdrawings, specifications standards, and inspec-tion requirements, to identify an item or rangeof items.

d. Federal Supply Code for Manufacturer(FSCM). The FSCM is a 5 digit numeric codeused to identify the manufacturer, distributor,or Government agency, etc., and is identified inSB 708-42.

e. Description. Indicates the Federal itemname and a minimum description required toidentify the item.

f. Unit of Measure (U/M). Indicates the stan-dard of basic quantity of the listed item as usedin performing the actual maintenance function.This measure is expressed by a two-characteralphabetical abbreviation, (e.g., ea, in., pr, etc).When the unit of measure differs from the unitof issue, the lowest unit of issue that will satisfythe required units of measure will be requisi-tioned.

3

g. Quantity (Furnished with Equipment (Basic models. Identification of the usable on codesIssue Items Only). Indicates the quantity of thebasic issue item furnished with the equipment. Code Used on

4. Special Information 1 AN/TNH-2AUsable on codes are included in description 2 AN/TNH-2Bcolumn. Uncoded items are applicable to all

Section Il. BASIC ISSUE ITEMS LIST

are as follows:

(1)Illustration (2)

Federal(A) (B) stockFig. Item numberno. no.

1 5835-503-1643

5835-503-1638

(3) (4) (5) (6)Part Description Unit

FSCM ofnumberUsable meanson code

SC-DL-292607

SC-DL-292567

80063

80063

CASE, AMPLIFIER 1.2 EACY-1830/TNH-2A,24-1/4 IN. LG x 20-1/4IN. X 13-1/4 IN. H O/ACASE, SOUND RECORDER EAREPRODUCER CY-1831/TNH-2A, 20-1/2 IN.LG X 19-3/4 IN, W X 15-3/4 IN. H, LUGGAGETYPE CASE

(7)Qtyfurnwith

equip

4

By Order of the Secretary of the Army:

Official:VERNE L. BOWERSMajor General, United States ArmyThe Adjutant General

Distribution:Active Army

USASA (2)CNGB(1)ACSC-E (2)Dir of Trans (1)COE (1)TSG (1)USAARENBD ( 1 )USAMB (10)AMC (1)MICOM (2)TECOM (2)FORSCOM (5)ARADCOM (2)ARADCOM Rgn (2)OS Maj Cored (4)LOGCOMD (3)USA STRATCOM (4 )MDW(1)Armies (2)Corps (2)HISA (ECOM) (18)Instl (2) except

Ft Gordon (10)Ft Huachuca (10)Ft Carson (5)

USA CDCEC (10)Svc colleges (1)USASESS(5)USAINTS (3)USAADS (2)USAFAS (2)USAARMS (2)USAIS (2)USAES (2)AD (2) except

SAAD (30)LBAD (14)TOAD (14)ATAD (10)

Gen Dep (2)Six Sec. Gen Dep (5)

CREIGHTON W. ABRAMSGeneral, United States ArmyChief of Staff

Sig Dep (5)USMA (2)ATS (1)MAAG (1)WRAMC (1)USARMIS (1)USA ERDAA (1)USA ERDAW (1)Sig FLDMS (1)Units org under fol TOE: 1 ea

6 - 3 0 277 - 4 211-1611-9711-9811-11711-15811-500(AA-AC)1 2 - 3 212-3712-10712-1571 717-4219-3162 9 - 12 9 - 1 129-212 9 - 5 229-5629-13429-13630-60033-5003 737-424.5-5005 1 - 152-15 7

ARNG: State AG (3)USAR: None.For explanation of abbreviations used. see AR 310-.50.

5

Changes in force: C1, C2, C4, C6, and C7

TM 11-2583AC 7

SOUND RECORDER-REPRODUCER SETS AN/TNH-2A AND AN/TNN-2B

CHANGE HEADQUARTERS

DEPARTMENT OF THE ARMYNo. 7 WASHINGTON, D.C., 1 July 1964

TM1l-2583A, 30 January 1956, is changed as follows:

}Note. The parenthetical reference to a p r e v i o u schange (example: page 1 of C 6) indicates that per-tinent material was published in that change:

Page 1, paragraph 2 (page 1 of C 6). Deletesubparagraph c and substitute:

c. Reporting of Equipment Manual Improve.ments. The direct reporting, by the individualuser, of errors, omissions, and recommenda-tions for improving this manual, is authorizedand encouraged. DA Form 2028 (Recom-mended Changes to DA Publications) will beused for reporting these improvements. Thisform will be completed in triplicate using pen-cil, pen, or typewriter. The original and onecopy will be forwarded direct to CommandingOfficer, U. S. Army Electronics Materiel Sup-port Agency, ATTN: SELMS-MP, Fort Mon-mouth, N.J. 07703. One information copy willbe furnished to the individual’s immediate su-

pervisor (officer, noncommissioned officer, su-pervisor, etc.).

Page 83 (page 5 of C 6), last two lines.Change appendix II to appendix III; changesection III to section II.

Appendix III, section II. Make the followingchanges:

(Page 6 of C 6), Federal stock number col-umn, 5995-259-2090. Make the followingchanges: Federal stock number column, change5995-259-2090 to 5995-889-1304. Descriptioncolumn, change approx 6 ft lg o/a to approx6 ft 9 in lg o/a.

(Page 7 of C 6), Federal stock number col-umn, 5835493-1983. Description column,change H3-L5 to 43-1.5.

TAGO 5068A–Jul


Official:J. C. LAMBERT,Major General, United States Army,The Adjutant General.

Distribution:Active Army:

USASA (2)CNGB (1)CofT (1)CofEngrs (1)TSG (1)CofSpts (1)C/COMMEL (7)USAARMBD (2)USAARTYBD (2)USARADBD (5)USAAESWBD (5)USCONARC (5)USAMC (5)USAECOM (7)USAMICOM (4)USASMCOM (2)ARADCOM (2)ARADCOM Rgn (2)OS Maj Cored (3) except

USARSOUTHCOM (2)USARYIS (2)

OS Base Comd (2)LOGCOMD (2)MDW (1)Armies (2) except EUSA (5)Corps (2)USA Corps (3)llth Air Assault Div (3)nstl (2) except

Ft Monmouth (63)Ft Hancock (4), Ft Gordon (5)Ft Huachuca (10)Ft Leavenworth (6)Ft Devens, Ft Lee (6)Camp LeRoy Johnson (5)

Svc Colleges (2)Br Svc Sch (2) except

USAIS (20, USACSC (30),USAADS, USAAVNS (20)

USMA (20)USAWC (20)GENDEP (OS) (2)Sig Sec, GENDEP (OS) (5)Sig Dep (OS) (12)Army Dep (2) except Sharpe (3)

Lexington, Tobyhanna (12)Sacramento (28), Ft Worth (8)Letterkenny, Navajo (6)Savanna (5), Utah (8)

EARLE G. WHEELER,General, United States Army, Chief of Staff.

Charleston (3), Atlanta (8)New Cumberland (8)

USASCC (4)USAECDA (1)USACBRCDA (1)USACECDA (1)USACECDA (Monmouth Ofc) (1)USAMSCDA (1)USAOCDA (1)USAQMCDA (2)USATCDA (1)USAADCDA (1)USAARMCDA (2)USAAVNCDA (1)USAARTYCDA (1)USASWCDA (1)USA Elct Mat Agcy (9)USASA 1st Fld Sta (5)USAPA (5)USATC AD (2)USATC Armor (3)USATC Engr (2)USATC Inf (3)USASTC (3)WRAMC (1)Army Pic Cen (2)BAMC (5)USASTC (S)USA SW Cen (5)Chicago Proc Dist (1)AMS (1)USAELRDA (White Sands) (13)Army Tml (1) except Oakland (S)POE (1)Sig Fld Maint Shops (3)WSMR (5)USATTCARC (1)USATTCA (1)USATTCG (1)USATTCP (1)USAERDL (2)USA Cold Rgn RE Lab (2)William Beaumont Gen Hosp (5)Valley Forge Gen Hosp (5)KMAG (5)Units org under fol TOE:

(2 copies each except as indicated)8-3027

2AGO 5068A

7-427-6210-2211-1611-5711-9711-9811-11711-15511-15711-500 (AA-AE) (4)11-55711-58711-59211-59712-3212-3712-10712-1571 717-217-42

NC: State AG (3).USAR: None.For explanation of abbreviations used, see AR 32O-5O.

29-56

17-6219-25219-26619-31629-129-229-1129-2129-6128-52

30-600 (AA-AE)33-500 (AA-AC)33-600 (AA-AC)3737-4245-500 (AA-AB)51-152-15767-6

3

TM 11-2583A*C 6

TECHNICAL MANUAL

SOUND RECORDER-REPRODUCER SETS AN/TNH-2A AND AN/TNH-2B

TM 11-2583A } HEADQUARTERS,DEPARTMENT OF THE ARMY

CHANGES No. 6 WASHINGTON 25, D.C., 7 June 1963

TM 11–2583A, 30 January 1956, is changed as follows:

Note: The parenthetical reference to previous changes (example: “page 1 of C 4“) indicates that pertinentmaterial was published in that changes.

Page 1. Make the following changes:

Paragraph 1. Add paragraph 1.1 afterparagraph 1.

1.1. Index of Publications

Refer to the latest issue of DA Pam 310–4 todetermine whether there are new editions,changes, or additional publications pertainingto the equipment. DA Pam 310– is an indexof current technical manuals, technical bulle-tins, supply bulletins, lubrication orders, andmodification work orders that are availablethrough publications supply channels. The in-dex lists the individual parts (–10, –20, –35P,etc. ) and the latest changes to and revisions ofeach equipment publication.

Paragraph 2 (page 1 of C 4). Delete para-graph 2 and substitute:

2. Forms and Records

a. Reports of Maintenance and Unsatisfac-tory Equipment. Use equipment forms and rec-ords in accordance with instructions in TM 38-750.

b. Report of Damaged or Improper Ship-ment. Fill out and forward DD Form 6 ( Re-port of Damaged or Improper Shipment) asprescribed in AR 700–58 (Army), NAV-SANDA Publication 378 (Navy), and AFR71–4 (Air Force).

c. Comments on Manual. Forward all com-ments on this publication direct to: Command-

ing Officer, U.S. Army Electronics MaterielSupport Agency, ATTN: SELMS–MP, FortMonmouth, N.J. (DA Form 1598 (Record ofComments on Publications), DA Form 2496(Disposition Form), or letter may be used.)

Page 24. Delete paragraph 31 and substi-tute:

31. Organizational TooIS, Materials, and Test EquipmentRequired

The tools, materials, and test equipment re-quired for organizational maintenance of SoundRecorder-Reproducer Sets AN/TNH–2A andAN/TNH–2B are listed below.

a.

b.

Tools. Tool Equipment TE–41.

Materials.(1)

(2)(3)(4)(5)

Cleaning compound (Federal stockNo. 7930-395-9542) .Cleaning cloth.Petrolatum (PET).Oil (OAI).Fine sandpaper (supplied in Tool

c .

Equipment TE–41 ).

Test Equipment.(1)(2)(3)(4)(5)

Scale, spring, 8-ounce.Scale, spring, 32-ounce.Multimeter AN/URM-105.Test Set, Electron Tube TV-7/U.Demagnetizer, Ampex No. 704.

• These changes supersede C 5, 4 May 1962.

1

Page 25. Delete paragraphs 32 through 34and figures 14 and 15 and substitute:

32. Scope of Operator’s MaintenanceThe maintenance duties assigned to the oper-

ator of the recorder-reproducer set are listedbelow together with a reference to the para-graphs covering the specific maintenance func-tion. The duties assigned do not require toolsor test equipment other than those issued withthe equipment.

a. Daily preventive maintenance checks andservices (par. 34).

b. Weekly preventive maintenance checksand services (par. 34.1 ).

c. Cleaning (par. 34.2).

33. Operator’s Preventive MaintenancePreventive maintenance is the systematic

care, servicing, and inspection of equipment toprevent the occurrence of trouble, to reducedowntime, and to assure that the equipment isserviceable.

a. Systematic Care. The procedures givenin paragraphs 34, 34.1, and 34.2 cover routinesystematic care and cleaning essential to properupkeep and operation of the equipment.

b. Preventive Maintenance Checks and Serv-ices. The preventive maintenance checks andservices charts (pars. 34 and 34.1), outlinefunctions to be performed at specific intervals.These checks and services are to maintainArmy electronic equipment in a combat serviceable condition; that is, in good general (physi-cal) condition and in good operating condition.To assist operators in maintaining combat serviceability, the charts indicate what to check,how to check, and what the normal conditionsare; the References column lists the illustra-tions, paragraphs, or manuals that contain de-tailed repair or replacement procedures. If thedefect cannot be remedied by the operator,higher echelon maintenance or repair is re-quired. Records and reports of these checksand services must be made in accordance withthe requirements set forth in TM 38-750.

34. Daily Preventive Maintenance Checks and Services Chart

SequenceNo..

1

23

4

5

6

7

Item

Recorder-reproducer set. . . . . . . .

Exterior surfaces. . . . . . . . . . .External receptacles . . . . . . . . . . . .

Glass. . . . . . . . . . . . . . . . . . .

Knobs, controls, and switches

Meter pointer . . . . . . . . . . . . . . . . . . ..

Operation .. .. . . . . . . . . . . . . . . . ..

Procedure

Check equipment for completeness andgeneral condition.

Clean exterior surfaces of the equipment.Inspect external receptacles for breakage

and firm seating.Inspect front-panel glass windows for dam-

aged housing, broken glass, physical dam-age, dust, or moisture.

During operation (item 7), check knobs,controls, and switches for proper mechani-cal action. Action must be positive with-out backlash, binding, or scraping.

During operation (item 7), check for stick-ing meter pointer movement.

During operation, be alert for any unusualperformance, response, or condition.

References

Appx III.

Para 34.2.

2

34.1. Weekly Preventive Maintenance Checks and Services Chart

SequenceNo.

1

2

3

Item Procedure

Cables.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

H a r d w a r e . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P rese rva t ion

Inspect external cables for cuts, cracked, orgouged jackets, fraying, or kinks.

Inspect all exterior hardware for loosenessand damage. The recorder-reproducer setcover, carrying handle, hinges, inputbinding posts, and all bolts and screwsmust be tight and not damaged.

Inspect the equipment to determine that itis free of bare spots, rust, and corrosion.If these conditions exist, refer to higherechelon for repair.

34.2. Cleaning

Inspect the exterior of the recorder-repro-ducer set. The exterior surfaces should be clean,and free of dust, dirt, grease, and fungus.

a. Remove dust and loose dirt with a cleansoft cloth.

.Warning: Cleaning compound is flammable

and its fumes are toxic. Provide adequate ven-tilation. Do not use near a flame.

b. Remove grease, fungus, and ground-indirt from the cases; use a cloth dampened (notwet) with cleaning compound.

c. Remove dust or dirt from plugs and jackswith a brush.

Caution: Do not press on the meter face(glass) when cleaning; the meter may be dam-aged.

d.. Clean the front panels, meters, and controlknobs; use a soft clean cloth. If dirt is difficultto remove, dampen the cloth with water; usemild soap if necessary.

343. Scope of Organizational Maintenance

The maintenance duties assigned to the or-ganizational repairman of the recorder-repro-ducer set are listed below together with a refer-ence to the paragraph covering the specificmaintenance function. The duties assigned re-

References

quire tools and test equipment as specified inparagraph 31.

a .and

b .

c .

d .

40).

f .

g.

Monthly preventive maintenance checksservices (par. 34.5).

Lubrication (par. 35).

Rustproofing and painting (par. 37).

Visual inspection (par. 39).

Electron tube replacement procedure (par.

Fuse replacement (par. 41).

Troubleshooting by using equipment per-fo rmance check l i s t (pa r . 42) .

34.4. Monthly MaintenancePerform the maintenance functions indicated

in the monthly preventive maintenance checksand services chart (par. 34.5) once each month.A month is defined as approximately 30 calen-dar days of 8-hour-per-day operation. If theequipment is operated 16 hours a day, themonthly preventive maintenance checks andservices should be performed at 15-day inter-vals. Adjustment of the maintenance intervalmust be made to compensate for any unusualoperating conditions. Equipment maintainedin a standby (ready for immediate operation)condition must have monthly preventive main-tenance checks and services performed on it.Equipment in limited storage (requires servicebefore operation) does not require monthly pre-ventive maintenance.

3

34.5. Monthly Preventive Maintenance Checks and Services Chart

SequenceNo.

1

2

3

45

6

7

8

9

1011

12

13

14

15

16

Item

Publications

Modification work orders

Completeness..........................

Cleanliess.................................Preservation...............................

External receptacles. . . . . . . . . . . . ..

Glass. . . . . . . . . . . . . . . . . . .. . . . . . . . ..

Cables..............................

Hardware...... . . . . . . . . . . . . . . . . .

Pilot lamps . . . . . . . . . . ...Fuses.. . . . . . . . . . . . . . . . . . . . . . . . . . .

Tubes . . . . . . . . . . . . . . . . . . . . . .

Lubrication ........................

Knobs, controls, and switches

Meter pointer . . . . . . . . . . . . . . . ..

Performance. . . . . . . . . . . . . . .

Procedure

Inspect manual for completeness and to seeif it is in usable condition, without miss-ing pages. Be sure that all Changes tothe manual are on hand.

Check to see that all URGENT MWO’s havebeen applied and that all ROUTINEMWO’s have been scheduled.

Check the equipment for completeness andgeneral condition.

Clean exterior surfaces of the equipment.Inspect the equipment to determine that it

is free of bare spots, rust, and corrosion.Inspect external receptacles for breakage

and firm seating.Inspect front-panel glass windows for dam-

aged housing, broken glass, physical dam-age, dust, or moisture.

Inspect external cables for cuts, cracked, orgouged jackets, fraying, or kinks.

Inspect all exterior and interior hardwarefor looseness and damage. The recorder-reproducer set cover, carrying handle.hinges input binding posts, and all boltsand screws must be tight and not dam-aged.

Check seating and condition of pilot lamps.The fuses in use should be 3 amperes, 250

volts, type F02G3R OOA (Federal stocknumber 5920-O10-6625).

Check seating of tubes.

Lubricate the equipment in accordance withparagraph 35.

During operation (item 16), observe thatthe mechan,ical action of each knob, con-trol, and switih is smooth and free of ex-ternal or internal binding.

During operation (item 16), check for stick-ing meter pointer movement.

Check the equipment performance checklist(par. 43).

References

DA Pam 310-4.

DA Pam 310–4

Appx III.

Par. 34-2.Par. 37.

Fig. 12 and 13.Par. 41 and fig. 12

and 13.

Par. 40 and fig. 16and 17.

Par. 43

Page 29. Delete paragraph 36. faces by lightly sanding them with fine sand-Delete paragraph 37 and substitute: paper. Brush two thin coats of paint on the

bare metal to protect it from further corrosion.37. Rustproofing and Painting Refer to the applicable cleaning and refinish-

Remove rust and corrosion from metal sur- ing practices specified in TM 9–213.

Page 89, appendix I and II (pages 1 and 8 of C 4). Renumber the existing appendixes as “II”and “III.”

Add appendix “I” before appendix “II.”

4

A P P E N D I X I

REFERENCE

Following is a list of publications available to the operators and repairmen of Sound Recorder-Reproducer Sets AN/TNH–2A and AN/TNH-2B:

DA Pam 3104 Index of Technical Manuals, Technical Bulletins, Supply Bulletins,Lubrication Orders, and Modification Work Orders.

TM 9–213 Painting Instructions for Field Use.

TM 11–5097 Spectrum Analyzers TS-723A/U, TS–723B/U, and TS-723C/U.

TM 11–6625-203-12 Operation and Organizational Maintenance, Multimeter AN/URM-105, Including Multimeter ME-77/U.

TM 11–6625–218-12 Operation and Organizational Maintenance, Frequency Meter AN/TSM-16.

TM 11-6625-261-12 Operator’s and Organizational Maintenance Manual, Audio Oscil-lators TS-382A/U, TS-382B/U, TS-382D/U, TS-382E/U, andTS-382F/U.

TM 11-6625-274-12 Operator’s and Organizational Maintenance Manual, Test Sets, Elec-tron Tube TV-7/U, TV-7A/U, TV–7B/U, and TV-7D/U.

TM 11–6625-316-12 Operator and Organizational Maintenance Manual, Test Sets, ElectronTube TV-2/U, TV-2A/U, TV–2B/U, and TV–2C/U.

TM 11-6625-320-12 Operator’s and Organizational Maintenance Manual, Voltmeter, MeterME-30A/U, and Voltmeters, Electron ME-30B/U, and ME-30C/U.

TM 38-750 The Army Equipment Records System and Procedures.

Appendix 11 (as added by C4, 17 October 1961 and changed by C 5, 4 May 1962). Deletesection III and substitute:

Section II. FUNCTIONAL PARTS LIST

5

6

7

8 DESIGNATIONFEDERAL STOCK NUMBER UNITBY MODEL D E S C R I P T I O N ILLUSTRATION

O F EXPISSUE. . . . . FIG. NO. ITEM NO.

1 2 AN/TNH-2A AND AN/TNH-2B (continued)

5960-166-7664 ELECTRON TUBE : MIL type 12AX7 1 4

5920-296-1517 FUSE, CARTRIDGE : 3 amp ; 250v MIL type F03G3R00A 5 4

6240-155-8706 LAMP, INCANDESCENT : 6-8v; mazda bulb; MIL Spec MS-15571-2type TB-14

1 4

AMPLIFIER POWER SUPPLY AM-1251/TNH AND AMPLIFIERPOWER SUPPLY AN-1634/TNH-2B

5960-262-0218 ELECTRON TUBE : MIL type 5Y3WGTA 1 4

5960-188-8500 ELECTRON TUBE: MIL type 6C5 1 4

5960-262-0163 ELECTRON TUBE: MIL type 6SN7WGTA 1 4

5960-248-1274 ELECTRON TUBE: MIL type 5879 1 4

5920-296-1517 FUSE, CARTRIDGE : 3 amp ; 250v; MIL F03G3R00A 5 4

6240-155-8706 LAMP, INCANDESCENT: 6-8v; madza bulb; MIL Spec MS-15571-2 1 4type TB-14

QTYI N

UNIT


EARLE G. WHEELER,General, United States Army,

Official: Chief of Staff.

J. C. LAMBERT,Major General, United States Army,The Adjutant General.

Distribution:

Active Army:

DASA (6)USASA (2)CNGB (1)CofEngrs (1)TSG (1)CSigO (5)CofT (1)USA CD Agcy (1)USCONARC (5)USAMC (5)ARADCOM (2)ARADCOM Rgn (2)OS Mai Cored (3)OS Base Cored (2)LOGCOMD (2)USAECOM (5)USAMICOM (3)USASCC (4)MDW (1)Armies (2)Corps (2)USA Corps (3)USATC AD (2)USATC Engr (2)USATC Inf (2)USATC Armor (2)Instls (2) except

Ft Monmouth (63)Svc College (2)Br Svc Sch (2)GENDEP (OS) (2)Sig Dep (OS) (12)Sig See, GENDEP (5)Army Dep (2) except

Ft Worth (8)Lexington (12)Sacramento (28)

Tobyhanna (12)USA Elct RD Actv, White Sands (13)USA Elct RD Actv, Ft Huachuca (2)USA Trans Tml Cored (1)Army Tml (1)POE (1)USAOSA (1)AMS (1)WRAMC (1)AFIP (1)Army Pic Cen (2)USA Mbl Spt Cen (1)USA Elct Mat Agcy (12)Chicago Proc Dist (1)USARCARIB Sig Agcy (1)Sig Fld Maint Shop (3)c/Spt Svcs (1)Units org under fol TOE:Two copies each UNOINDC:

7 19-2527–62 19-25611-7 19-31611-16 29-111-57 29-2111–97 29-5611–117 30-600 (AA-AE)11-155 32-5111–157 32-5611–500 (AA-AC) (4) 32-5711–587 33-600 (AA-AC)11–592 45-500 (AA–AC)11-597 51-112-32 52-112–107 5 712–157 57-617–2 57-617-62

NG: State AG (3) ; units—same as active Army except allowance is one copy each unit.

USAR: None.

For explanation of abbreviations used, see AR 320–50.

9

DEPARTMENT OF THE ARMY TECHNICAL MANUALDEPARTMENT OF THE AIR FORCE TECHNICAL ORDER

TM 11-2583ATO 31S3-2TNH2-21C HANGES No. 4

TM 11-2583ATO 3153-2TNH2-21

* C 4

DEPARTMENTS OF THE ARMY ANDTHE AIR FORCE

WASHINGTON 25, D.C., 17 October 1961

SOUND RECORDER-REPRODUCER SETS AN/TNH-2AAND AN/TNH-2B

TM 11-2583A, 30 January 1956, is changed as follows:Page 1. chapter 1, Note (page 1 of C 2) (as changed by C 3, 16 Mar 59)Line 4. Change “AM-1634/THN-2B” to AM-1634/TNH-2B.Line 6. Change “RD-149/THN-2B” to RD-149/TNH-2B.

Change “AN/THN-2B” to AN/TNH-2B.Line 8. Change “AM-1634/THN-2B” to AM-1634/TNH-2B.Line 11. Change “AN/THN-2B” to AN/TNH-2B.

Page 1, paragraph 2. Add subparagraph d.d. Comments or Suggestions.Any comments concerning omissions and discrepancies in Appendix I and Appendix II will be

prepared on DA Form 2028 and forwarded direct to Commanding Officer, U.S. Army Signal MaterielSupport Agency, ATTN: SIGMS-ML, Fort Monmouth, N.J.

Figure .49 (foldout). (As changed by C 3, 16 Mar 59) Reverse the connections of terminals “B” and“D" of P103 .

APPENDIX I (ADDED)MAINTENANCE ALLOCATION

RECORDER-REPRODUCER SET, SOUNDAN/TNH-2A AND AN/TNH-2B

* These changes supersede C 3, 16 March 1959, and together with C1, 21 June 1961, TM 11-2583, 15 November 1954, supersede TM 11-5835-205-10P, 12 March 1959. including C 1, 2 May 1960,and so much of TM 11-5835 -205-20P, 12 March 1959, as pertains to maintenance allocation.

1

SECTION I. INTRODUCTION

1. General

a. This appendix assigns maintenance func-tions to be performed on Components, assem-blies, and sub-assemblies by the lowestappropriate maintenance echelon.

b. Columns in the maintenance allocationchart are as follows:

(1) Component. This column shows only thenomenclature or standard item name.Additional descriptive data is includedonly where clarification is necessary toidentify the component. Components, as-semblies, and sub-assemblies are listed intop-down order. That is, the assemblieswhich are part of a component are listedimmediately below that component, andthe sub-assemblies which are part of anassembly are listed immediately belowthat assembly. Each generation break-down (components, assemblies, or sub-assemblies) are listed in disassembly or-der or alphabetical order.

(2) Maintenance function. This column indi-cates the various maintenance functionsallocated to the echelons.

(a)

(b)

(c)

(d)

(e)

( f )

(g)

2

Service. To clean, to preserve, and toreplenish lubricants.Adjust. To regulate periodically to pre-vent malfunction.Inspect. To verify serviceability and todetect incipient electrical or mechani-cal failure by scrutiny.Test. To verify serviceability and todetect incipient electrical or mechani-cal failure by use of special equipmentsuch as gages, meters, etc.Replace. To substitute serviceable com-ponents, assemblies, or sub-assemblies,for unserviceable components, assem-blies, or sub-assemblies.Repair. To restore an item to service-able condition through correction of aspecific failure or unserviceable condi-tion. This function includes but is notlimited to welding, grinding, riveting,straightening, and replacement ofparts other than the trial and errorreplacement of running spare typeitems such as fuses, lamps, or electrontubes.Align. To adjust two or more compo-nents of an electrical system so thattheir functions are properly synchro-nized.

(h)

(i)

Calibrate. To determine, check, or rec-tify the graduation of an instrument,weapon, or weapons system, or compo-nents of a weapons system.Overhaul. To restore an item to com-pletely serviceable condition as pre-scribed by serviceability standardsdeveloped and published by heads oftechnical services. This is accom-plished through employment of thetechnique of “Inspect and Repair Onlyas Necessary” (IROAN). Maximum uti-lization of diagnostic and test equip-ment is combined with minimumdisassembly of the item during theoverhaul process.

(j) Rebuild. To restore an item to a standard as near as possible to original ornew condition in appearance, perform-ance, and life expectancy. This is ac-complished through the maintenancetechnique of complete disassembly ofthe item, inspection of all parts or com-ponents, repair or replacement of wornor unserviceable elements using origi-nal manufacturing tolerances and/orspecifications and subsequent reassem-bly of the item.

(3)

(4)

(5)

1st, 2d, 3d, .4th, 5th echelon. The symbol Xindicates the echelon responsible for per-forming that particular maintenance op-eration, but does not necessarily indicatethat repair parts will be stocked at thatlevel. Echelons higher than the echelonmarked by X are authorized to performthe indicated operation.Tools required. This column indicatescodes assigned to each individual toolequipment, test equipment, and mainte-nance equipment referenced. The grouping of codes in this column of themaintenance allocation chart indicatesthe tool, test, and maintenance equipment required to perform the mainte-nance function.Remarks. Entries in this column will beutilized when necessary to clarify any ofthe data cited in the preceding columns.

c. Columns in the allocation of tools for mainte-nance functions are as follows:

(1) Tools required for maintenance functions.This column lists tools, test, and mainte-

(2)

(3)

ance equipment required to perform the 2. Maintenance by Using Organizationsmaintenance functions. When this equipment is used by signal services

1st, 2d, 3d, 4th, 5th echelon. The dagger organizations organic to theater headquarters or

(t) symbol in these columns indicates the communication zones to provide theater commu-

echelons normally allocated the facility. nications, those maintenance functions allocatedup to and including fourth echelon are author-

Tool code. This column lists the tool code ized to the organization operating this equip-assigned. ment.

3

4 SECTION II MAINTENANCE ALLOCATION CHART

(1)

PART OR COMPONENT

RECORDER-REPRODUCED SET, SOUNDAN/TNl-2A; AN/TNl-2B

AMPLIFIER, AUDIO FREQUENCY AM-1249/U

AMPLIFIER-POWER SUPPLY GROUPAM-1251/TNl (P/O AN/TNi-2A ONLY)

AN/TNl-2& AN/TNl-2B 2

(2) (3) (4) (5) (6) (7)

MAINTENANCEFUNCTIONS

service

adjust

inspect

testrepairoverhaulservice

inspect

test

replacerepairoverhaulservice

adjust

inspect

test

replacerepairoverhaul

1STCCH

X

X

X

X

X

X

X

X

X

2NDCCH

X

X

X

X

X

X

X

X

XX

X

3RDCCH—

X

X—

X

X

X

4THCCH—

X

X

X

X

X

—5THCCH

—

(8)

TOOLSREQUIRED

1211

1,2,12,14

1112143

14

118,10,14

3,4,5,7,10,11

3,4,5,7,8,10,11

1433

14

3,5,11,13

148,10,11

3,4,5,7,10,11

3,4,5,7,8,10,11

1433

(9)

REMARKS

Exterior

Operational adjustmentInternal (Level adjustments)Exterior

Operational

Clean externally

Fuse, Pilot light external componentsInternal componentsContinuity, tubes, voltageGeneral operation of components including

output levels and distortion measurementsFinal testing. Use tool code 9 in lieu

of 10 for fifth echelon

Cleans externally

Controls in course of operationInternal level controlsFuse, lampInternal componentsContinuity, voltage, tubesGeneral operation incl’d output levels

and distortion measurementFinal testing. Use tool cede 9 in lieu


5

(1)

PART OR COMPONENT

AN/TNl 2A; AN TN1 2B (Continued)AMPLIFIER-POWER SUPPLY AN-1631

TN1-2B (P O AN TN1-2B ONLY)

CABLE ASSEMBLIES, POWER ELECTRICAL

CASE AMPLIFIER CY-1830 TN1-2A

CASE, SOUND RECORDER-REPRODUCER_CY-1831 TN1-2A; CY-1831/TNl-2B_HEADSET, ELECTRICAL H-104/G

MICROPHONE, DYNAMIC M-65/U

(2)

MAINTENANCEFUNCTION

service

adjust

inspect

test

replacerepairoverhaul—repair

replacerepairreplacerepair replacereplace

(3) (4) (5) (6) (7) (8)—1ST1.11

X

X

X

XX

2ND1.11

—

X

XX

X

3RD1.11

——

X

X

X

X

X

X

4TH1.11—

X

X

—

X

——

—

5TH1.11

—

TOOLSREQUIRED

11

3,5,11,13

118,10,11

3,4,5,7,10,11

3,4,5,7,8,10,11

1433

3

(9)

REMARKS

Cleans external components

Controls in course of operationInternal level controlsFuse, lampInternal componentsContinuity voltage, tubesGeneral operation incl. output level

and distortion measurementsFinal testing, use tool code 9 in lieu


See separate MACSee separate MAC

AN TN1-2A; AN TN1-2B

6

(1) (2) (3) (4) (5) (6) (7) (8) (9)

PART OR COMPONENT MAINTENANCE 1ST2ND 3RD 4TH5TH TOOLSFUNCTION 1.11 1.11 1.11 1.11 1.11 REQUIRED

REMARKS

AN/TNl-2A: AN/TNl-2B (continued)RECORDER REPRODUCER SUB-ASSEMBLY service X Cleans external components

RG 446 TN1-2A (CPO AN/TNl-2A ONLY) X 11adjust X Controls in course of operation

X 1, 2, 14 Mechanical, solenoid, break belt, pressure rollerinspect X External components

X 14 Internal componentstest X 12 Operation

X 1,2, 12, 14 Mechanical operation onlyX 1 thru 6, 11 Final testing

12, 13, 151, 2,3,5,7,8, 11

X 12, 13, 15replace X 14repair X 3overhaul X 3

RECORDER-REPRODUCER SUB-ASSEMBLY, service X Clean external componentsSOUND RD-49/TNl-2B X 14(P/O AN/TNI-2B ONLY)

adjust X controls in course of operationX 1,3, 14 Mechanical, solenoid, break belt,

pressure rollerinspect X External components

11 Internal componentstest X 12 Operation

X 1,2, 12, 14 Mechanical operation onlyX 1 thru 8, 11 Final testing

12, 13, 15X 1, 2,3, 5,7, 9, 11

12, 13, 15replace X 14repair X 3overhaul X 3

7

(1)

SECTION III ALLOCATION CONTRCLS FOR MAINTENANCE FUNCTIONS

TOOLS REQUIRED FOR MAINTENANCE FUNCTIONS

AN/TN1-2A; AN/TN1-2B (continued)SCALE, SPRING 8 OZ. FSN 6670-599-5296SCALE, SPRING 32 OZ. FSY 6670-291-8721TOOL EQUIPMENT TE-87/USPECTRUM ANALYZER TS-733/UAUDIO OSCILLATOR TS-382A/UFLUTTER, INDICATOR PH-593/PFQFREQUENCY METER AN/TSM-16MULTIMETER AN/URM-105TEST SET, ELECTRON TUBE TV-2/UTEST SET, ELECTRON TUBE TV-7/UVOLTMETER ME-30/UDEMAGNETIZER AMPEX NO. 704

TAPE ALIGNMENT IS TPS AMPEX NO. 4494TOOL EQUIPMENT TE-410-12 LBS SCALE FSN 6670-001-9013

(2) (3) (4) (6) (7) (8)

REMARKS

To be standardized

APPENDIX II (Added)

BASIC ISSUE ITEMS FOR RECORDER-REPRODUCER SETS, SOUND

AN/TNH-2A AND AN/TNH-2B

Section I. INTRODUCTION

1. Scope

a. This appendix lists items supplied for initialoperation and for running spares. The list in-cludes tools, accessories, parts, and material is-sued as part of the major end item. The listincludes all items authorized for basic operatormaintenance of the equipment. End items ofequipment are issued on the basis of allowancesprescribed in equipment authorization tables andother documents that are a basis for requisition-ing.

b. Columns are as follows(1)

(2)

(3)

(4)

(5)

Source, maintenance, and recoverabilitycode. Not used.Federal stock number. This column liststhe 11-digit Federal stock number.Designation by model. The dagger (†) in-dicates the model in which the part isused.Description. Nomenclature or the stand-ard item name and brief identifying datafor each item are listed in this column.When requisitioning, enter the nomen-clature and description.Unit of issue. The unit of issue is each,unless otherwise indicated, and is thesupply term by which the individual itemis counted for procurement, storage, req-uisitioning, allowances, and issue pur-poses.

(6)

(7)

(8)

Expendability. Nonexpendable items areindicated by NX. Expendable items arenot annotated.Quantity authorized. Under “Items Com-prising an Operable Equipment,” the col-umn lists the quantity of items suppliedfor the initial operation of the equipment.Under “Running Spares and AccessoryItems,” the quantities listed are thoseissued initially with the equipment asspare parts. The quantities are author-ized to be kept on hand by the operatorfor maintenance of the equipment.Illustration. The “Item No.” column liststhe reference symbols used for identifica-tion of the items in the illustration ortext of the manual.

2. ReferencesAdditional instructions concerning mainte-

nance of this equipment are contained in:Operator and Organizational Maintenance Re-

pair Parts and Special Tools List and Mainte-nance Allocation Chart:

TM 11-5965-217-12P, Microphone, DynamicM-65/U

Operator, Organizational, Field and DepotMaintenance Repair Parts and Special ToolsLists and Maintenance Allocation Chart:

TM 11-5965-210-15P, Headset, ElectricalH-l04/G, H-l04A/G, H-l04B/G

8

SECTION II FUNCTIONAL PARTS LIST

(4)(1)

SOURCEMAINTE-NANCE

ANDRECOVER-ABILITY

(2) (3)

DESIGNA-TIONBY

MODEL

(5) (6) (7) (8) (9)

ILLUSTRATIONS

FlGURENO

FEDERALSTOCK NUMBER

DESCRIPTION ITEMNO

CODE

RECORDER-REPRODUCER SET SOUND, AN/TMI-2A: magnetic recording tape type, med0.350 in w; 15 in to 7.5 in per recording speed 40 to 10,000 cps ± 2 db; fren response 8 w out-

put, 600 ohms imped; Luggage case type: 115 v, 60 cyc single ph; Ampex model No. 402P

RECORDER-REPRODUCER SET, SOUND AN/TMI-2B: magentic type; 600 ohmsImpedance; tape type; 1/1 in w; 7 1/2 in and 15 in per see; 50 to 10,000 cps ± 2 db fren response8 w; 117 v 60 eye, single ph; spcl features, provision for remote control

5835-543-0079

ITEMS COMPRISING AN OPERABLE EQUIPMENT

2

1

NOTE: Model column 1 refers to AN/TMI-2A: Column 2 refers to AN/TMI-2B

TECHNICAL MANUAL TM 11-2583A:

AMPLIFIER, AUDIO FREQUENCY AM-1249/U: 5 w power output; 117 v. 60 eye, single pchannel input; 50,000 ohm impedance; Sig Corp dwg DL-282750 (Installed in equip)

AMPLIFIER-POWER SUPPLY AM-1251 /TMI-2A: provides amplification and erasesignal for motor board assembly; 19 in lg x 7 in h x 14 in w o/a; Sig dwg SC-DL-282772(Installed in equip)

AMPLIFIER-POWER SUPPLY, AM-1631 /TMI-2B: AF amplr; 8 w output; 600 ohmsimpedance; Power-Supply 1.6 amp, 5 v, 117 v, 60 cyc single ph; 7 in x 14 in x 19 in o/a;Telectro part No. TA-543A (Installed in equip)

CABLE ASSEMBLY, POWER, ELECTRICAL CX-1208/U: 2 cond; approx 6 ft lg o/a; 2No. 18 AWG Sig Corp dwg SC-D-25128 (Not installed)

CABLE ASSEMBLY, POWER, ELECTRICAL CX-1208/U: 2 cond;approx 10 ft lg o/a; 2 No. 18 AWG; Sig Corp dwg SC-D-25128 (Not installed)

CABLE ASSEMBLY, RADIO FREQUENCY CG-1368/U: 1 cent, RG-58/U;6 ft lg o/a; one end PJ-0558, sec end Cannon XL-3-12; Tekctro Indpart TC-1383 (Not installed)

CASE, AMPLIFIER CY-1830/TMI-2A: 24 1/4 lg x 20 1/4 in w x 13 1/4 in h o/a;Sig dwg DL-292607 (Not installed)

CASE, SOUND RECORDER-REPRODUCER CY-1831/TMI-2A: 20 1/2 in lg x 19 3/4 in wx 15 3/4 in h o/a; Luggage type case; Sig dwg SC-DL-292567 (Not installed)

HEADSET, ELECTRICAL H-104/G: Dynamic type; 300 ohms non-impedance connected inparalled-earphones 2 in dia x 1 in d o/a; Cord 5 ft lg with plug-in term (Not installed)

Ord thru AGC

5830-537-7755

5830-537-7756 1

15835-543-0080

5995-259-2090 1

15995-161-2572

5995-296-1607

NX

NX

5835-503-1643 1

5835-503-1638 1

5965-296-9910 NX 1

(1)

SOURCEMAINTE-NANCE

ANDRECOVER-ABILITY

CODE

(2) (3) (4) (5) (7) (8) (9)

ITEMNO

DESIGNA-TIONBY

MODEL

FEDERALSTOCK NUMBER

DESCRIPTION

AN/TMI-2A, AN/TMI-2B (continued)

MICROPHONE, DYNAMIC M-65/U: 150 ohms impedance 100 to 10,000 cyc freq range(Not installed)

RECORDER-REPRODUCER SUB ASSEMBLY RD-146/TMI-2A: c/o tape transportmechanism, recording head, reproducing head, erasing head; 19 in lg x 15 3/1 in h x 6 1/2 indeep; Sig Corp dwg SC-DL-282901 (Installed in equip)

RECORDER-REPRODUCER SUB-ASSEMBLY, SOUND RD-149/TMI-2B: c/o 1 ea tapetransport mechanism, recording head, reproducing head, 2 motors, single ph: 6 1/2 in x 15 3/4in x 19 in o/a dim; remote operations; Telectro part No. TA-542A

REEL, SOUND, RECORDING TAPE: std 10 1/2 in reel; American Molded ProductsRETMA 10 1/2 in (Installed in equip)

SPLICER, MAGNETIC RECORDING TAPE: steel; 1 1/2 in by 2 3/8 in by 5 7/8 in o/adia; Robbins Ind part TS4 (Not installed)

TAPE, LEADER TIMING, RECORDER, REPRODUCER: paper; 3 3/4 in lg x 0.250 in w; MinMining type No. 43-1,5 (Not installed)

TAPE, SOUND RECORDING: 1/4 in w; 2400 ft lg; Fedtype TAT-A-FT-2400-250-PA (Not installed)

TAPE, SPLICING, RECORDER-REPRODUCER: plastic; base; white: 0.50 w x 0.002 in thk;Spool2 in cd x 1 1/16 in id x 1/2 in thk o/a; Minn Mining type No. 41-1/21. (Not installed)

1

1

1

1

1

1

1

1

1

2

5965-296-3117 NX

NX

NX

5835-537-7788

5835-543-0081

5835-521-5766 H414

MS2

5820-566-0668

5835-393-1983

5635-583-1296 H415

5835-537-7812

AMPLIFIER-POWER SUPPLY GROUP AM-1634 /TMI-2B

CONNECTOR, PLUG, ELECTRICAL: 10 male cent; 10 amps 730 v;Jones type P310-FMT (Installed in equip)

5935-187-0716 J107

RECORDER-REPRODUCER SUB-ASSEMBLY RD-146/TMI-2AAND

RECORDER-REPRODUCER SUB-ASSEMBLY, SOUND RD-149/TMI-2B

5835-509-8442 HOLDER, REEL: used to mount reels of tape; Telectro Ind Corp part/dwgNo. TR-605 (Installed in equip)

02640265

11

(1)

SOURCEMAINTE-NANCE

ANDRECOVER-

ABILITYCODE

(2) (3) (4) (5) (7) (8) (9)

ILLUSTRATIONS

ITEMNO.

DESIGNA-FEDERAL TION

STOCK NUMBER BYMODEL

DESCRIPTION FIGURENO.

—

AN/TMI-2A, AN/TMI-2B (continued)

RUNNING SPARES AND ACCESSORY ITEMS

RECORDER-REPRODUCER SET, SOUND AN/TMI-2A, AN/TMI-2B

TAPE, SOUND RECORDING: 1/4 in w; 2400 ft lg; Fed spec No: TAT-A-FT-2400-250-PA(Not mounted)

5835-583-1296 14

AMPLIFIER-AUDIO FREQUENCY AM-1249/U

ELECTRON TUBE MIL type 5Y3WGTA (Not mounted)ELECTRON TUBE: MIL type 6V6GT (Not mounted)

5960-262-02185960-116-9927

11

V301V303V304

--—.

5960-166-76645920-010-66526240-155-8706

ELECTRON TUBE: MIL type 12AX7 (Not mounted)FUSE, CARTRIDGE: 3 amps, 250 v; MIL-F-15160 type F02G3800A (Not mounted)

_LAMP, INCANDESCENT 6-8 v Mazda bulb; GE part No. 47 (Not mounted)

151

11

V103V106V102V107V101V104

AMPLIFIER-POWER SUPPLY GROUP AM-1251 /TMI-2AAND

AMPLIFIER-POWER SUPPLY GROUP AM-1634 /TMI-2B

5960-262-02185960- 188-8500

ELECTRON TUBE: MIL type 5Y3WGTA (Not mounted?.. ___ _____ELECTRON TUBE: MIL type 6C5 (Not mounted)

11

5960-188-3577 ELECTRON TUBE: MIL type 6SN7WGT (Not mounted) 1

5960-248-1274 ELECTRON TUBE: MIL type 5879 (Not mounted) 1

5

1

V105F101F102

—FUSE, CARTRIDGE: 3 amps, 250 v; MIL type MIL-F-15160, type F02G3800V (Not mounted]

LAMP, INCANDESCENT 6-8 v Mazda type ; GE part No. 47 (Not mounted)

5920-010-6652

6240-155-8706 —

B Y O R D E R O F T H E S E C R E T A R I E S O F T H E A R M Y A N D T H E A I R FO R C E:

Official:J. C. LAMBERT,

Major General, United States Army,The Adjutant General.

Official:R. J. PUGH,

Colonel, United States Air Force,Director of Administrative Services.


DASA (6)USASA (2)CNGBTech Stf, DA (1)

except CSigO (18)Tech Stf Bd (1)USCONARC (5)USAARTYBD (1)USAARMBD (2)USAIB (1)USARADBD (2)USAABELCTBD (1)USAAVNBD (1)USAATBD (1)ARADCOM (2)ARADCOM Rgn (2)OS Maj Comd (3)OS Base Cored (2)LOGCOMD (2)MDW (1)Armies (2)Corps (2)Instl (2)Ft Monmouth (63)USATC AD (2)USATC Armor (2)USATC Engr (2)USATC FA (2)USATC Inf (2)

USAOMC (3)Svc Colleges (2)Br Svc Sch (2)GENDEP (2) except

Atlanta GENDEP (None)Sig Sec, GENDEP (5)Sig Dep (12)

USA Trans TMl Cored (1)Army Tml (1)

Valley Forge Gen Hosp (5)William Beaumont Gen Hosp (5)Blue Grass Ord Dep (5)Erie Ord Dep (5)Letterkenny Ord Dep (5)Sierra Ord Dep (2)Umatilla Ord Dep (3)Red River Arsenal (5)QMRECOMD (5)USAEPG (2)AFIP (1)AMS (1)Army Pictorial Cen (2)EMC (1)Yuma Teat Sta (2)USACA (3)USASSA (20)USASSAMRO (1)USASEA (1)

G. H. DECKER,General, United States Army,

Chief of Staff.

CURTIS E. LEMAY,Chief of Staff United States Air Force.

USA Caribbean Sig Agcy (1)USA Sig Msl Spt Agcy (13)Sig Fld Maint Shops (3)USA Corps (3)JBUSMC (2)AFSSC (1)JCA (5)USAPA (5)USA SPWAR Cen (5)USAWC (5)Units org under fol TOE:

(2 cy each UNOINDC)7 17-27-6211-711-1611-5711-9711-11711-15511-500 (AA-AE) (4)11-55711-58711-59211-59712-3212-10712-15717

NC: State AG (3); units-same as Active Army except allowance is one copy to each unit.

17-6219-25219-25619-31629-5630-600 (AA-AE)32-5132-5632-5733-7733-600 (AA-AC)45-500 (AA-AC)51-15 757-557-6

USAR: None..

For explanation of abbreviations used, see AR 320-50.

12

TM 11-2583AC2

T E C H N I C A L M A N U A L

SOUND RECORDER-REPRODUCER SETS AN/TNH-2A AND AN/TNH-2B

TM 11-2583ACHANGES No. 2

TM11–2583A, 30 January 1956, is changed asfollows:

The title is changed to read: Sound Recorder-Reproducer Sets AN/TNH-2A and AN/TNH-2B.

The following information changes TM 11-2583A so that the manual applies also to thefollowing equipment:

Nomenclature Order No. Serial No.Sound Recorder-Repro- 43076-PH-56 1 through 192

ducer Set AN/TNH-2B

Page 1, chapter 1. Add the following note atthe beginning of the chapter:

Note. The components of Sound Recorder-ReproducerSet AN/TNH-2B are similar to the corresponding com-ponents of Sound Recorder-Reproducer Set AN/TNH-2Aexcept that in addition Amplifier-Power Supply AM-1634/THN-2B and Sound Recorder-Reproducer Ssembly RD–149/THN-2B, components of the AN/THN-4-2B, provide for remote control operation. Ruggedizedtubes are used in the AM–1634/THN-2B and in AudioFrequency Amplifier AM-1249/U (Order No. 43076-PH-56). All information in the manual applies equally tothe AN/THN-2B unless otherwise specified.

Add “(6V6GTY) on the AN/TNH-2B)” after“6V6GT” in the following places in the manual:

Page 38, paragraph 44c(3).

Page 39, figure 20.

Page 65, figure 35.

Fold-out, figure 48.

Add “(5Y3GTA on the AN/TNH-2B)” after“5Y3GT” in the following places in the manual:

Page 37, paragraph 44b(1).

Page 38, paragraph 44c(1).

Page 65, figure 35.


AGO 3846A-Jan

DEPARTMENT OF THE ARMYWASHINGTON 25, D. C., 17 January 1957

Add “(6SN7WGT) on the AN/TNH-2B)” after“6SN7” in the following places in the manual:

Page 36, figure 18.

Page 37, paragraph 44b (2).

Page 37, paragraph 44b (4).

Page 44, figure 24.


Page 1, paragraph 3a. Add the following afterthe last sentence:

Sound Recorder-Reproducer Set AN/TNH-2Bprovides for remote operation.

Page 2, paragraph 5. Make the followingchanges:

Change the paragraph heading to read:Table of Components of Sound Re-corder-Reproducer Set AN/TNH-2A(figs. 1-4) .

Delete the introductory sentence.

In the Required No. column of Power CableAssembly CX-1208/U (6 ft 0 in.)change 2 to read: 1.

In the Component column) following PowerCable Assembly CX-1208/U (6 ft 0in.) add: Power Cable Assembly CX-1208/U (10 ft 0 in.).

On the same line, add 1 in the Required No.column; add 120 in the width column.

In t he Componen t co lumn , a f t e r CX-1208/U, add: (6 ft 0 in.).

In the Component column, following CX-1208/U, add: CX-1208/U (10 ft 0 in.).

On the same line, in the Required No. col-umn, add: 1; in the Depth column,add: 120.

1

5.1. Table of Component of Sound Recorder-Reproducer Set AN/TNH-2B(figs.1-4)(Added)

Amplifier Power Supply AM-1634/TNH-2B - - - - -Recorder-Reproducer Subassembly RD-149/TNH-2BAudio, Frequency Amplifier AM-1249/U - - - - - -Sound Recorder-Reproducer Case CY-1831/TNH-2A Amplier Case CY-1830/TNH-2A - - - - - - - - -Dynamic Microphone M-65/U, consisting of: - - - -

Dynamic Microphone M-44 A/U - - - - - - - -Microphone Stand MT-1583/U- - - - - - - - -

Electrial Headset H-118/U- - - - - - - - - -Raider Frequency Cable Assembly CG-1368/U - - - -Power Cable Assembly CX-1208/U (6 ft 0 in.) - - - - - -Power Case Assembly CX-1208/U (10 ft 0 in. ) - - - -Special Purpose Electrical Cable Assembly CX-3322/U

(20 ft 0 in.).Remote control connector (male) (fig. 29.1) - - - - - -Tape reels (15 w/tape, 1 empty)- - - - - - - - - - -

Running spares consisting of:Tubes:

1 2 A X 7 - - - - - - - - - - - - - - - - - -5 8 7 9 - - - - - - - - - - - - - - - - - - - - - - - -6 V 6 G T Y - - - - - - - - - - - - - - - - - - - -5 Y 3 G T A - - - - - - - - - - - - - - - - - - - - - - -6 S N 7 W G T - - - - - - - - - - - - - - - - - -6 C 5 - - - - - - - - - - - - - - - - - - - - - - - -

Fuses: 3 amp - - - - - - - - - - - - - - - - - - - Pilot lamps - - - - - - - - - - - - - - - - - - - - - - Cables:

CX-1208/U (6 ft 0 in.) - - - - - - - - - - - - -CX-1208/U (l0 ft 0 in.) - - - - - - - - - - - -

1111111111111

116

11111155

11

Page 9, paragraph 6b. After the third sentence,add: A female connector and a mating male con-nector are located on the rear of the chassis ofAmplifier-Power Supply AM-1634/TNH-2B. Themale connector, furnished with the equipment,when inserted, prepares the equipment for localoperation. When removed, the remote controlcircuit of the recorder-reproducer set is opened.Insertion of the male connector of the remotecontrol device (not furnished) arranges this cir-cuit for remote control operation of the equipm e n t .

Page 5, figure 4 (Cl). Add the following noteto figure 4:

NOTE. ON THE AN/TNH-2B, ONLY 5 SPAREFUSES AND 5 SPARE PILOT LAMPS ARE SUP-PLIED: A SPARE SOUNDHEAD ASSEMBLY ISNOT SUPPLIED.

2

76½

10½16½14144½8

- - - - - -

---- - - -

5/8

- - - - - -

1415¾

72124½

626

------

------

------

1919192121½

10½(dia)

------------

- - - - -

------

7272

120240

- - - -

72120

1.11.2

.84.24.4

.04

2539193641

Page 6, paragraph 6.

i. 1. (Added) Power ab le Assembly CX-1208/U (10 ft 0 in:). This cable is a two-con-ductor, rubber-covered, 10-foot cable, one end ofwhich is terminated with a female connector andthe other = terminated with a male connector.

Page 3, paragraph 7. Make the fol lowingchanges.

Change Recorder-Reproducer SubassemblyRD-1461/TNH-2A to read: Recorder-Reproducer Subassembly RD-146/TNH-2A.

Change the last item in the chart to read:Power Cable Assembly CX-1208/U (10ft 0 in.).

Add the following note to figures 6, 8, 9, 10,11, 12, 27, 28, 29, and 42:

AGO 3846A

NOTE. ON THE AN/TNH-2B, A REMOTE CON-TROL CONNECTOR IS LOCATED TO THE LEFTOF THE POWER CABLE CONNECTOR AT THEREAR OF THE AMPLIFIER CHASSIS.

21.1. Remote Operation of AN/TNH-2B(Added)

To use the AN/TNH-2B with remote control,proceed as follows:

a. Connect the equipment for the type of opera-tion desired (pars. 11 and 13).

b. Remove the remote control male connector(furnished with the equipment), from the rearof the amplifier chassis.

c. Insert the remote control unit male connectorinto the 10-contact female connector on the rearof the amplifier chassis.

d. Adjust the equipment controls (fig. 13) forthe type of operation desired (pars. 13-23).

e. Operate the recorder-reproducer set usingthe remote control unit.

f. When remote operation is completed, removethe remote control unit male connector from therear of the amplifier chassis.

g. Insert the male connector (b above) into thefemale connector on the rear of the amplifierchassis .

Page 24, paragraph 29a: Add the followingat the end of the chart:

I t em Function

Remote control connector Provides a connection for re-mote control operation.

Page 24, paragraph 30. In the second sentence,after “authorized”, insert: by.

Page 33, paragraph 43. Add the following afterthe paragraph heading:

Note. On the AN/TNH-2B, make sure the remotecontrol connector, (furnished with the equipment), is in-serted in its receptacle ( rear of amplifier) (fig, 29.1)before checking the equipment as indicated in the checklist below.

Page 40, paragraph 49. Make the followingchanges:

In a, last sentence, change “capacitators” toread: capacitor.

In c, after the third sentence, insert: (On theAN/TNH–2B, the dc circuit of solenoid

L202 is closed through Switch S208through contacts H and F of connectorsP205 (fig. 50.1) and P103 (fig. 49.1),and contacts 7 and 8 of connectors P105and J107.

Page 41, paragraph 50b. After the second sentence, insert: (On the AN/TNH-2B, the 115-voldc output of rectifier CR201 is connected to thecoil of relay K202 through switches S202 andS201, and through contacts H and F of connectorsP205 and P103, through contacts 7 and 8 of connectors P105 and J107, and through switch S207(figs. 49.1 and 50.1. ).)

Page 41, paragraph 51b. After the first sen-tence, insert: (On the AN/TNH–2B, the dc out-put of the rectifier is connected to the high side ofthe coil of relay K203 through switches S202 andS201, through contacts H and F of connectorsP205 and J 107, and contacts 7 and 8 of connetorsP105 and J107, switch S205, and through con-tacts 7 and 8 of relay K202). )

Page 47, paragraph 57b. Make the followingchanges:

Tenth line, change “R304” to read: R302.Eleventh line, change “R304” to read: R302.

Page 47, figure 26. Desgnate reference symbolR303, and a value of 220 ohms to the cathode re-sistor of tube V302A.

Page 49, paragraph 60. Insert the following inthe list:

Fig. No. Title

29.1

30.1

31.1

34.1

49.1

50.1

62.1

53.1

Part of amplifier chassis (AM-1634/TNH-2B),bottom view, showing connectors for remoteoperation.

Amplifier chassis (AM-1634/TNH-2B), re-sistor-capacitor board (nearer to panel).

Amplifier chassis (AM-1634/TNH-2B), re-sistor-capacitor board (farther from panel).

Voltage and resistance chart, amplifier (AM-1634/TNH-2B).

Amplifier (AM-1634 TNH-2B), schematic dia-gram.

Recorder-reproducer (RD-149/TNH-2B), sche-matic diagram.

Amplifier (AM-1634/TNH-2B), wiring dia-gram.

Recorder-reproducer (RD-149/TNH-2B), wir-ing diagram.

AGO 3S46A 3

Page 51, paragraph 63. Make the followingChanges:

In the heading, change (fig. 27,28,29,30,and 31) to read: (figs. 27, 28, 29, 29.1,30, anti 31).

In a, at the end of the first sentence, insert:On the AM-1634/TNH-2B, measure theresistance between pins D and G of con-nector P 103.

In f, after “figure 34”, add: or figure 34.1.In g, after “figure 34”, add: or figure 34.1.

Page 57, paragraph 65. Add the following op-posite “symptom No. 1“:

Probable cause Remedy

D e f e c t i v e c o n n e c t o r P 1 0 5 . R e p l a c e c o n n e c t o r P 1 0 5 .

D e f e c t i v e c o n n e c t o r J 1 0 7 , R e p l a c e c o n n e c t o r J 1 0 7 .

Page 63, paragraph 67d At the end of the sub-paragraph, after “34,” insert: 34.1.

Page 63, paragraph 69. Under the paragraphheading, after “49,” add: and 49.1.

Page 64, figure 34. Make the followingchanges:

Pin 7 of XV103. Substitute 3.15 AC for “20”.Pin 8 of XV103. Substitute 20 for “3.15 AC”.

Figure 29.1. (Added) Part of amplifier chassis (AM-1634/TNH–2B), bottom view, showing connectors for remoteoperation.

4

TM2583A-C2-5

Figure 49.1. (Added) Amplifier (AM-1634/TNH-2B), schematic diagram.

TM2583A-C2-6

Figure 50.1. (Added) Recorder-reproducer (RD-149/TNH-2B), schematic diagram.

TM2583A-C2-8

Figure 52.1. (Added) Amplifier (AM-1634/TNH-2B), wiring diagram.

TM2583A-C2-7

Figure 53.1. (Added) Recorder-reproducer, (RI) 148/TNH-2B), wiring diagram.

1. ALLAND

NOTES:VOLTAGES ARE ABOVE THE LINE 4. ALL RESISTANCES MEASURED TOARE DC. GROUND WITH METER SELECTOR

2. ALL RESISTANCES ARE BELOW IN PLAYBACK LEVEL , ANDTHE LINE.

3. ALL VOLTAGES MEASURED WITHRECORD LEVEL , AND PLAYBACK LEVEL

MULTIMETER TS-352/U CONTROLS OPERATED TO SETTING 10(20000 OHMS/VOLT), OR EQUAL. TM2583A-C2-2

Figure 30.1. (Added) Arnplifier chassis (AM-1634/TNH-2B), resistor-capacitor board (nearer to panel).

NOTES:1. ALL VOLTAGES ARE ABOVE THE 4. ALL RESISTANCES MEASURED TO

LINE AND ARE DC. GROUND WITH METER SELECTOR2. ALL RESISTANCES ARE BELOW

THE LINE.IN PLAYBACK LEVEL , AND

3. ALL VOLTAGES MEASURED WITHRECORD LEVEL , AND PLAYBACK LEVEL

MULTIMETER TS-352/U(20000 OHMS/VOLT, OR EQUAL. CONTROLS OPERATED TO SETTING 10

T M 2 5 8 3 A - C 2 - 3

Figure 31.1. (Added) Amplifier chassis (AM-/1634/TNH-2B),resistor-capacitor board (farther from panel).

AGO 8846A 5

6

Figure 34.1. (Added) Voltage and resistance chart, amplifier (AM-1634/TNH-2B).

AGO 3846A

By Order of Wilber M. Brucker, Secretary of the Army:

MAXWELL D. TAYLOR,General, United States Army,

Official: Chief of Staff.HERBERT M. JONES,



CNGBASATec Svc, DATec Svc Bd .Hq CONARCCONARC BdCONARC Bd Test SecArmy AA CoredOS Maj CoredOS Base CoredLog CoredMDWArmiesCorpsDivFt & CpSp Wpn CoredArmy Cml CenGen & Br Svc SchGen DepotsSig See, Gen DepotsSig DepotsUS Army Tng CenPOE (OS)Trans Terminal CoredArmy Terminals

NG: State AG; units—same as Active Army.USAR: None.For explanation of abbreviations used, see SR 320-50-1.

OS Sup AgenciesArmy Elet PGSig Fld Maint ShopsSig LabACSMil DistUnits org under fol TOE:

11-7C11-16C11-57C11-127R11-128C11-500R11-557C11-587R11-592R11-597R12-35R32-51R32-55R32-56R32-57R3 3 6 7 R33-77R45-500R (AA-AC)

7

TM 11-2583AC1

TECHNICAL MANUAL

SOUND RECORDER-REPRODUCER SET AN/TNH-2A

TM 11-2583A D E P A R T M E N T O F T H E A R M Y

C H A N G E S N o . 1 W A S H I N G T O N 25, D. C., 9 M a r c h 1 9 5 6

T M 1 1 - 2 5 8 3 A , 3 0 J a n u a r y 1 9 5 6 , i s c h a n g e d a s f o l l o w s :

P a r a g r a p h 5 . A d d t h e f o l l o w i n g a f t e r “ T a p e r e e l s ” :

Required Height DepthComponent Width Volume Weight(in.) (cu ft) (lb)

Tape splicer . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 ½ 5 ¾ 2 ¾ 0.015 0.25Splicing tape . . . . . . . . . . . . . . . . . . . 2 3¾ 3 3 . 0 3 . 0 5Leader and timing tape . . . . . . . . . . . . . . . . . . 1 3/8 3 3 .015 . 0 5

No. (in.) (in.)

Paragraph 6. Make the following changes:f. Add the following after the last sentence:

Amplifier Case CY-1830/TNH-2A alsocontains splicing tape, leader and timingtape, and a tape splicer (fig. 4).

m. ( A d d e d ) Tape Splicer (fig. 4). This is amanually operated devicc used to splice tornrecording tape or to splice portions of the leaderand timing tape to the recording tape.

n. (Added) Splicing Tape (fig. 4). This is anadhesive-type tape, ½ inch wide by 150 incheslong, used to splice torn recording tape or tosplice the leader and timing tape to the recordingtape for editing purposes.

o. (Added) Leader and Timing Tape (fig. 4).This is a paper tape, ¼ inch by 150 inches long,marked with multicolored spots spaced 15 inchesapart. The tape is spliced to the recording tapeto indicate the beginning and end of the recorded data.The tape may be used to check the travel time (orspeed) of the recording tape.

Paragraph 13. Add the following to f:To identify the program to be recorded,

splice a portion of the leader and timingtape (par. 22) to the free end of the re-cording tape and identify the programon the face of the leader and timingtape.

Paragraph 14. Make the following changes:j. Add the following after the last sentence:

Use the leader and timing tape to identifyeach reel of tape (par. 13f).

l. Add the following after the last sentence:Use the leader and timing tape to identify

each set of intelligence. Splice the leaderand timing tape to the recording tape(par. 22). Use a sufficient length ofleader and timing tape to provide asuitable dead space. Identify each setof intelligence by marking the face ofthe leader and t iming tape with theappropriate information.

Paragraph 15f. Add the following: Use theleader and timing tape to identify each tele-phone conversation (par. 14l).

Paragraph 22.

22. Splicing Tape

(Superseded) (fig. 11.1)Splice the recording tape as follows:a. Place the two loose ends of the torn tape in

the tape guides with the glossy side of the tape up;be sure to overlap the ends at least ¼ inch.

b. Lower the tape fingers.

c. Push the knob of the splicer back to themiter position, and press the lever down (A, fig.11.1).

d. Raise the lever.e. Blow away the small pieces of tape that have

been cut from the tape.f. Apply a small strip of splicing tape over the

cut ends of the recording tape (B, fig. 11.1).g. Move the knob of the splicer to the trim

position and press the lever down. Trimmedsplicing tape should be slightly narrower thanthe recording tape (C, fig. 1 1.1)

h. Remove the tape from the splicer.

1

2

Figure 4. (Superceded) Accessories, running spares, and now components of Sound Recorder-Reproducer Set AN/TNH-2A.

Figure 11.1

Figure 11.1. (Added) Splicing tape.

35. Lubrication

(Superseded) (fig. 17.1 )a. General. Under severe salt-air conditions,

apply a small quantity of Cleaning Compound tothe contacts of the INPUT SELECTOR SWITCH,METER SELECTOR switch, and EQUALIZA-TION switch (fig. 12) of the amplifier, and thefunction switch of the audio amplifier (fig. 13 ) toremove corrosion. Remove tile Cleaning Com-pound residue and apply a very small quantity ofpetrolatum (PET) to the contacts. Only a verylight coating of petrolatum is required once an-nually under severe salt-air conditions.

b. Capstan Motor (fig. 17.1). Once every 1,000hours of operation, lubricate the capstan motor asfollows:

(2)

(3)

(4)TAGO 5573A

(1) Remove the four 10-32 screws that securethe louver to the front of the recorder-reproducer and remove the louver. Thecapstan motor is now exposed.Lift the oil filler cap, apply 2 drops of oil(OAI) to the bearing and close the oilfiller cap.Examine the chassis for drops of oil andremove oil if required.Replace the louver.

90.1 Timing(Added)

To check the tape-travel time of the recorder-reproducer, proceed as follows:

a. Prepare the equipment for 7½ ips operation(par. 14).

b. Install and thread the leader and timing tape.c. Turn on the equipment and allow at least a

5-minute warmup time.d. Press the PLAY and RECORD switches.e. Check the timing, using an accurate stop

watch, by counting the number of colored patcheson the tape entering the soundhead assembly.One hundred patches should enter the soundheadin 3 minutes and 20 seconds.

f. If timing is incorrect by more than ½ of 1percent, check the power frequency and the pres-sure roller adjustment (par. 78).

g. If timing is still incorrect, replace the capstanmotor (par. 73).

h. Move the 7½"-15" switch to the 15" posi-tion and check the timing at 15 ips. One hundredpatches should enter the soundhead in 1 minuteand 40 seconds.

i. If timing is incorrect, repeat procedure in fand g above.

3

4

Figure 17.1 (Added) Capstan motor, location oil filler cap.

[AG 413.44 (7 Mar 56) ]


MAXWELL D. TAYLORGeneral, United States Army,

Offic ial :JOHN A. KLEIN,

Major General, United States, Army, The Adjutant General

Chie f o f S ta f f .

DISTRIBUTION:Active Army:

CNGB (1)Tee Svc, DA (1) except CSIGO (30)Tee Svc Bd (1)Hq CONARC (5)CONARC Bd(Incl ea Test Sec (1)Army AA Comd (2)OS Maj Comd (5)OS Base Comd (5)Log Comd (5)MDW (1)Armies (5)Corps (2)Tng Div (2)Ft & Cp (2)Gen & Br Svc Sch (5) except Sig

Sch (25)Gen Depots (2) except Atlanta Gen

Depot (None)Sig See, Gen Depots (10)

Sig Depots (20)Trans Terminal Cond (2)Army Terminals (2)OS Sup Agencies (2)Sig Fld Maint Shops(3)Sig Lab (5)Mil Dist (1)Units organized under following

TOE’s:7R. Inf Div (2)11-7R, Sig Co, Inf Div (2)11–16R, Hq & Hq Co, Sig Bn,

Corps or Abn Corps (2)11–57R, Armd Sig, Co (2)11-127R, Sig Rep Co (2)11-128R, Sig Depot Co (2)11-500R (AA-AE), Sig Svc Org

(2)11-557C. Abn Sig Co (2)

NG: State AG (6); units- same as Active Army except allowance is one copy per unit.USAR: None.For explaination of abbreviations used, see SR 320-50-1.

11587R, Sig Base Maint Co (2)11-592R, Hq & Hq Co, Sig Base

Depot (2)11-597R, Sig Base Depot Co (2)12-35R, Sp Band (2)12- 107-C. Org or Sep Band (2)17R, Armd Div (2)32-51R, Hq & Hq Co, Comm

Recon Gp (U) (2)32-55R, Comn Recin Bn (U) (2)32-56R, Hq & Hq Co, Comm

Recon Bn (U) (2)32–57R, Comm Recon Opr Co

(U) (2)32-500R (AA-AG), Comm Re-

con) or (U) (2)33–77R Loundspeaker and Leaflet

Co Army (2)

5TAGO 5573A

TECHNICAL MANUALNO. 11-2583A

TM 11-2583A

CHAPTER 1.

Section I.

II.

CHAPTER 2.

CHAPTER 3.

Section I.

II.

CHAPTER 4.

Section I.

II.

III.

IV.

V .

CHAPTER 5.

CHAPTER 6.

Section I.

II.

III.

IV.

CHAPTER 7.

INDEX

DEPARTMENT OF THE ARMYWASHINGTON 25, D.C., 30 JANUARY 1956

SOUND RECORDER-REPRODUCER SET AN/TNH-2A

ParagraphlNTRODUCTION

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 2

Description and data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

lNSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-12

OPERATION

Operation under usual conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-23

Operation under unusual conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 24-27

ORGANIZATIONAL MAINTENANCE

Controls and instruments , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28, 29

Organizational tools and equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30, 31

Preventive maintenance services . . . . . . . . . . . . . . . . . . . . . . . . 32-34

Lubrication and weatherproofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35-37

Trouble shooting at organizational maintenance level . . . . . . . . . . . . . . . . . . . 36-43

THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44-68

FIELD MAINTENANCE

Trouble shooting at field maintenance level . . . . . . . . . . . . . . . . . . . . . . . . . 59-69

Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70-74

Mechanical adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75-78

Final testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79-94

SHIPMENT AND LIMITED STORAGE AND DEMOLITION TOPREVENT ENEMY USE . . . . . . . . . . . . . . . . . . . . 95-98

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

1

1

7

13

21

2 3

24

25

2 9

31

3 7

48

66

7 0

7 1

8 2

85

i

Figure 1. Sound Recorder-Reproducer Set AN/TNH–2A, set up for operation

CHAPTER 1

INTRODUCTION

Section I. GENERAL

1. Scopea. This manual contains information on

the operation, theory and maintenance ofSound Recorder-Reproducer Set AN/TNH-2A(fig. 1).

b. Forward comments on this publicationdirectly to Commanding officer, The SignalCorps Publications Agency, Fort Monmouth,New Jersey.

2. Forms and Records

a. Unsatisfactory Equipment Reports.(1) DA Form 468, Unsatisfactory Equip- ment Report, will be filled out and

forwarded to the Office of the ChiefSignal Officer as prescribed in SR 700–45-5.

(2) DD Form 535, Unsatisfactory Report,will be filled out and forwarded toCommanding General, Air Materiel

Command, Wright-Patterson AirForce Base, Dayton, Ohio, as pre-scribed in SR 700–45-5 and AF TO00–35D–54.

b. Damaged or Improper Shipment. DDForm 6, Report of Damaged or Improper Ship-ment, will be filled out and forwarded as pre-scribed in SR 745–45–5 (Army) ; Navy Ship-ping Guide, Article 1850–4 (Navy) ; and AFR71–4 (Air Force).

c. Preventive Maintenance Forms.(1)

(2)

DA Form 11–250, Operator FirstEchelon Maintenance Cheek List forSignal Corps Equipment, will be pre-pared in accordance with instructionson the back of the form (fig. 14).DA Form 11–251, Second and ThirdEchelon Maintenance Check List forSignal Corps Equipment, will be pre-pared in accordance with instructionson the back of the form (fig. 15).

Section Il. DESCRIPTION AND DATA

3. Purpose and Use

Sound Recorder-Reproducer Set AN/TNH-2A (fig. 1) is a self-contained portable electro-mechanical half-track magnetic tape recorderand reproducer for making and reproducingsound recordings. The sound is recorded onand reproduced from a 2,400-foot magnetictape moving-at a rate of either 7 ½ inches persecond (ips) or 15 ips.

a. Recorder. The equipment records speechor music from a microphone, telephone line, orprogram line source (par. 14, 15, and 16).

b. Reproducer. Recordings may be repro-duced (played back) immediately after rewind-ing (while recording) or simultaneously whilerecording through the self-contained loud-speaker or the headset (par. 18), or an ex-ternal 600-ohm program line, or an externalloudspeaker (par. 21).

c. Public Address. The recorder-reproducerset may be used also as a public address set(par. 21) to cover a limited area with the self-contained loudspeaker in Audio FrequencyAmplifier AM–1249/U, or a large area withsuitable external loudspeaker (not supplied).

1

4. Technical CharacteristicsPower source requirement. . . . 115 v ac, 60 CPS, single

phase.Power consumption:

Recorder- Reproducer Sub-assembly RD-146/TNH-2A and Amplifier-Powersupply AM-1251/TNH . . . 250 w.

Audio Frequency AmplifierAM-1249/U . . . . . . . . . . . . 60 w.

Audio power output . . . . . . . 8 W.Frequency range:

Tape speed 15 ips . . . . . . . . . 50 to 10,000 CPS ±2 db.Tape speed 7½ ids . . . . . . . . 50 to 7,000 CPS ±2 db.

Input impedance:Microphone . . . . . . . . . . . . . . 150 ohms.Bridge . . . . . . . . . . . . . . . . . . 20,0000 hmsLine, balanced or unbalanced 600 ohms.

Number of tubes:Amplifier-Power Supply

AM-1251/TNH . . . . . . . . . 8.Audio Frequency Amplifier

AM–1249/U . . . . . . . . . . . . 5.Recording-reproducing medium:

Type . . . . . . . . . . . . . . . . . . . . Magnetic tape, dualtrack.

Tape size . . . . . . . . . . . . . . ¼ in. wide. 2,400 ft long.Playing time . . . . . . . . . . . . . . . 1 hour, single track at

7 ½ ips; 2 hours, bothtracks at 7 ½ ips;½ hour, single track

5. Table of Components(fig. 1 through 4)

Fast winding time . . . . . . . . . .Fast rewinding time . . . . . . . .Headset . . . . . . . . . . . . . . . . . . .Microphone . . . . . . . . . . . . . . . .

Output impedance:Line . . . . . . . . . . . . . . . . . . . . .Monitor jack . . . . . . . . . . . . .Loudspeaker . . . . . . . . . . . . .Headset:

Amplifier-Power SupplyAM-1251/TNH . . . . . . .

Audio Frequency AmplifierAM-1249/U . . . . . . . . . .

Loudspeaker (internal ) :Type . . . . . . . . . . . . . . . . . . . .

Voice coil impedance . . . . . .Power rating . . . . . . . . . . . . .

Oscillator frequency . . . . . . . . .Flutter . . . . . . . . . . . . . . . . . . . .

Wow . . . . . . . . . . . . . . . . . . . . . .

Distortion . . . . . . . . . . . . . . . . . .

at 15 ips; 1 hour, bothtracks at 15 ips.

1 minute.1 minute.600-ohm impedance.Low impedance, dyna-

mic type.

600 ohms, balanced.50,000 ohms.8 ohms.

600 o h m s

8 ohms.

8 in., dynamic, perman-ent magnetic type.

6 to 8 ohms.8 w.

65 kc.Less than .2 per cent

root mean square(rms) at 15 ips.

Less than .25 per centrms at 15 ips.

Less than 3 percent rmsat 8 watts output.

The following table lists the components of Sound Recorder-Reproducer Set AN/TNH-2A.

Component

Amplifier-Power SupplyAM–1251/TNH

Recorder-Reproducer SubassemblyRD-146/TNH–2A

Audio Frequency AmplifierAM–1249/U

Sound Recorder-Reproducer CaseCY-1831/TNH-2A

Amplifier Case CY-1830/TNH-2ADynamic Microphone M-65/U,

consisting of:Dynamic Microphone

M-44A/UMicrophone Stand

MT-1583/UElectrical Headset H-118/URadio Frequency Cable Assembly

CG-1368/UPower Cable Assembly

CX-1208/U (6 ft 0 in.)Special Purpose Electrical Cable

Assembly CX-3322/U (20 ft 0 in.)

RequiredNo.

1

1

1

1

11

1

1

11

2

1

Height( in. )

7

6 ½

10 ½

16½

1414

4½

8

Depth( in. )

14

15¾

7

21

24 ¼6

2

6

Width( in. )

19

19

19

21

21 ½

72

72

240

Volume(cu ft)

1.1

1.2

.8

4.2

4.4

Weight(lb)

25

39

19

36

41

2

Component Required Height Depth Width Volume WeightNo. ( in. ) ( in. ) ( in. ) (Cu ft) (ib)

Tape Reels 16 (15 w/tape, 5/8 10½ dia .041 empty)

Running spares consisting of:Tubes:

12AX7 15879 16V6 15Y3GT 16SN7GT 16C5 1

Fuses: 3 amp 6Pilot (lamps) 6Cables:

CX-1208/U 1 72CG-1368/U 1 72

Soundhead assembly 1

6. Description of Equipment 1831/TNH-2A (fig. 2). This case is a gray,

a. General. Sound Recorder-Reproducer SetAN/TNH–2A consists of Amplifier-PowerSupply AM–1251/TNH and Recorder-Repro-ducer Subassembly RD-146/TNH–2A con-tained in Sound Recorder-Reproducer CaseCY–1831/TNH-2A, and Audio FrequencyAmplifier AM-1249/U, Dynamic MicrophoneM-65/U, Electrical Headset H–118/U, connect-ing cables, and running spares contained inAmplifier Case CY-1830/TNH-2A.

b. Amplifier-Power Supply AM–1251/TNH(fig. 1). This unit contains the recording am-plifier, the reproducer amplifier, the bias erase-oscillator, and a power supply. The front panelmounts the controls for operating these cir-cuits, as well as a record level indicator, avolume unit (vu) meter, and the necessaryconnectors and jacks for interconnecting thecomponents. The rear panel of this unit mountsthe fuses and connectors for alternating cur-rent (ac) input power. The rear panel isaccessible after opening the access door at therear of Sound Recorder-Reproducer Case CY-1831/TNH-2A.

c. Recorder-Reproducer Subassembly RD-146/TNH-2A (fig. 1). This subassembly is anelectromechanical unit which contains the tape-transport mechanism, the sound head assembly,and the operating controls mounted on the frontpanel. The under portion of the panel mountsthe motors, the electronic components, and theconnectors for power and signals.

d. Sound Recorder-Reproducer Case CY–

aluminum-clad, plywood case containing Re-corder–Reproducer Subassembly RD–146/TNH-2A and Amplifier-Power Supply AM–1251/TNH. .A door on the rear of the caseprovides access to the input power connectorand fuses.

e. Audio Frequency Amplifier AM–1249/U(fig. 1). This unit contains a power amplifierand a power supply circuit. The front panelmounts the loudspeaker, a level control, a selec-tor switch, a pilot light, fuse, and the necessaryoutput jacks. The rear panel of the unit mountsthe power connector and signal input connec-tor. The rear panel is accessible after openingthe access door at the side of Amplifier CaseCY-1830/TNH-2A.

f. Amplifier Case CY-1830/TNH-2A (fig, 3).This case is an aluminum-clad, plywood casecontaining Audio Frequency Amplifier AM-1249/U. Dynamic Microphone M-65/U, Elec-trical Headset H–118/U, Power Cable Assem-bly CX-1208/U, the interconnecting cables, aspare sound head assembly, running spares, 15reels of tape, one empty reel, and spare cablesare stored within the case.

g. Dynamic Microphone M-65/U (fig. 1).The microphone is a low-impedance directional-type microphone with a connector. The micro-phone consists of Dynamic Microphone M-44A/U and Microphone Stand MT-1583/U.

h. Electrical Headset H–118/U (fig. 4). Theheadset is a high-fidelity, dynamic-type, 600-ohm headset with a 5-foot connecting cordterminated with a telephone plug.

3

Figure 2. Sound Recorder-Reproducer Set AN/TNH–2A, carrying case.

Figure 3. Amplifier Case CY–1830/TNH-2A, cover removed, rear view, showinglocation of stowed material.

4

5

Figure 4. Sound Recorder-Reproducer Set AN/TNH-2A, accessories,running spares, and some components.

i. Power Cable Assembly CX–1208/U (6 ft0 in.) (fig. 4). This cable assembly is aconductor, rubber-covered, 6-foot cable, one endof which is terminated with a female connectorand the other end is terminated with a maleconnector.

j. Radio Frequency Cable Assembly CG–1368/U (fig. 4). This 6-foot, shielded, single-conductor, rubber-covered coaxial cable is ter-minated at one end in a female connector andat the other end in a telephone-type plug(PL–55).

k. Special Purpose Electrical Cable Assem-bly CX–3822/U (20 ft 0 in.) (fig. 4). This 20-foot two-conductor, shielded, rubber-coveredcable is terminated on one end with a femaleconnector and at the other end with a recessedmale connector.

7. Nomenclature Versus Common NamesThe following chart lists nomenclatures and

their respective common names used in thismanual.

Nomenclature Common name

Sound Recorder-Reproducer Set Recorder-reproducerAN/TNH-2A set

Recorder-Reproducer Subassembly Recorder-reproducer–RD–1461/TNH/2AAmplifier-Power Supply Amplifier

AM–1251/TNHAudio Frequency Amplifier Audio amplifier

AM-1249/UAmplifier Case CY–1830/TNH–2A Audio amplifier

carrying caseSound Recorder-Reproducer Case Recorder-reproducer

CY–1831/TNH-2A carrying caseDynamic Microphone M-65/U MicrophoneElectrical Headset H-118/U HeadsetPower Cable Assembly Interconnecting

CX–1208/U (6 ft) power cableSpecial purpose Electrical Cable Microphone cable

Assembly CX–3322/U (20 ft)Radio Frequency Cable Assembly Output cable

CG–1368/UPower Cable Assembly Power cable

CX–1208/U (6 ft)

6

CHAPTER 2

INSTALLATION

8. Packaging Data(fig. 5)

When packaged for export shipment, theequipment in the carrying cases is placedin moistureproof containers and packed in twowooden boxes. The following chart lists thecontents and dimensions of each box.

Dimension (in. )Box Volume WeightNo. Height Width Depth (curt) (lb)

1 23 27 27 9.4 1402 20 31 27 10 150

9. Unpacking and Checking(fig. 5)

a. General. When unpacking the equipment,be careful not to damage the carrying case bythrusting tools into the interior. Follow thedirections given below.

b. Unpacking.(1)

(2)(3)

(4)

(5)

(6)

(7)

‘Place the wooden packing case closeto the operating site.Cut and fold back the metal straps.Remove the nails with a nail puller.Remove the wooden cover and oneside of the wooden packing case.Slit the moistureproof barrier, andlift out the outer corrugated carton.Open the outer corrugated carton bycutting the sealing tape. Do not dam-age the carton.Slit the moisture-vaporproof barrier,and lift out the inner corrugatedcarton.Open the inner corrugated carton bycutting the tape that seals it. Removethe desiccant, and lift the carryingcase out of the carton.

(8) Open the carrying cases by unfasten-ing the latches. Check the contentsagainst the packing slip.

(9) Inspect the equipment thoroughly forshipping damage.

10. Installation of Equipmenta. General. The recorder-reproducer set is

packaged with all tubes and fuses in place,and with one end of the interconnecting powercable connected to the amplifier. The recorder-reproducer set may be rack-mounted (fig. 6)or it may be installed as a desk or table unitwith the components in their respective carry-ing cases (fig. 1) (with the carrying casesstacked or separated). Allow enough room foroperating the equipment.

b. Setting up Equipment in Carrying Cases.(1)

(2)

(3)

(4)

(5)

(6)

(7)

Unlatch and remove the covers ofboth carrying cases.Move the ON-OFF switch (fig. 7) onthe recorder-reproducer to the OFFposition.Turn the RECORD LEVEL control(fig. 12) of the amplifier to the 0position.Turn the INPUT SELECTORSWITCH of the amplifier to the MIC.position.Turn the METER SELECTOR con-trol of the amplifier to the RECORDLEVEL position.Connect the microphone cable to theINPUT connector (fig. 8) of the am-plifier by lining up the key on themicrophone cable connector with thekeyway on the INPUT connector, andpushing the connector.Open the access door at the back ofthe recorder-reproducer carrying case

7

Figure 5. Sound Recorder-Reproducer Set AN TNH-2A, packing and packaging diagram.

8

and insert the female connector ofthe interconnecting power cable inthe input power connector (fig. 12)on the rear of the amplifier chassis.Connect the male connector of thecable to a 115-volt 60-cycle per sec-ond (cps) power source.

Note. For telephone recordings, in-sert the male connector of the inter-connecting power cable in the AUXOUTLET receptacle as described inparagraph 11.

c. Setting up Equipment in Rack (fig. 6).(1)

(2)

(3)

(4)

To rack-mount the equipment, removethe four screws that hold the ampli-fier to its carrying case; remove thefour screws that hold the audio am-plifier to its carrying case, and removethe eight screws that hold the re-corder-reproducer to its carrying case.Lift the recorder-reproducer out ofthe carrying case and disconnect allcables. Identify each cable with a tagto indicate the correct connections.Install the recorder-reproducer in avertical position in a standard rack.Below the recorder-reproducer, installthe amplifier, and below the amplifierinstall the audio amplifier.Connect each cable to the properconnectors.

11. Connections to Telephone or ProgramLine

(fig. 9)a. Telephone Line Connection. The recorder-

reproducer set must be connected to a tele-phone line through authorized equipment suchas Tone Warning Group OA–145/GT (refer toTM 11-2088 Tone Warning Group OA-145/GT). The OA–145/GT provides an audible notethat informs the telephone user that the con-versation is being recorded. To connect theOA-145/GT to the recorder-reproducer set, setup the equipment (par. 10) and proceed asfollows :

(1)

(2)

Turn the INPUT SELECTORSWITCH of the amplifier to the 600BAL. position (fig. 12).Rotate the RECORD LEVEL controlto the 5 position. This setting mayhave to be changed later during the

(3)

(4)

(5)

recording operation to increase or de-crease signal strength as required.Insert the telephone plug, at the endof the headset cord, in the EAR-PHONES jack.Connect the male connector of thepower cable to the AUX OUTLETreceptacle at the rear of Tone Warn-ing Generator Control C-638/GT.Modify Special Purpose Cable Assem-bly CX–1278/U (part of the OA-145/GT ) as follows:

(a)

(b)

(c)

(d)

Remove the plug from one end andreplace it with a suitable connectorto mate with the INPUT connectorof the amplifier of the recorder-reproducer set.Dress the end of the black con-ductor and solder it to terminal 2of the connector.Dress the end of the white con-ductor and connect it to terminal 3of the connector.Connect the cable shield to terminal1 of the conductor.

(6) Connect the components of ToneWarning Group OA-145/GT as de-scribed in TM 11–2088. Connect theamplifier INPUT connector throughthe CX-1278/U to terminals markedT, R, and S of the terminal boardmarked RECORDER INPUT locatedon the rear of the C-638/GT asfollows:

(a) Connect the spade terminal of theblack wire of the CX–1278/U to theterminal marked T.

(b) Connect the spade terminal of thewhite wire of the CX-1278/U tothe terminal marked R.

(c) Connect the shield of the CX-1278/U to the terminal marked S.

(7) Connect the power cable of the C-638/GT to a 115-volt 60-cps powersource.

Note. With The recorder-reproducerset and the tone warning group con-nected as described above, the equipTent will start to record telephoneconversations when the PLAY andRECORD switches are pressed (par.15).

9

Figure 6. Interconnection diagram (rack mounting shown).

10

b. Program Line Connections (fig. 10). Theconnection between the recorder-reproducer setand the program line consists of a two-con-ductor shielded cord terminated at one endwith a connector suitable for connection to theprogram line and at the other end with afemale connector that mates with the INPUTconnector on the amplifier. To connect theequipment, proceed as follows:

(1)(2)

(3)

(4)

Set up the equipment (par. 10).Fabricate the connecting cord to therequired length and terminate thecord with appropriate connectors.Connect the two-conductor shieldedcable across the program line. Con-nect the other end of the cable to theINPUT connector on the amplifier.Turn the INPUT SELECTORSWITCH to the 600 BAL. position fora balanced line; to the 600 UNBAL.position for an unbalanced line; orto the BRIDGE position if bridging is

(5)

desired. (Bridging is used to avoidloading a program line excessively byutilizing the relatively high-impedancebridging input circuit of the ampli-fier.)Insert the plug at the end of the head-set cord into the EARPHONES jack.

12. Service Upon Receipt of Used or Recon-ditioned Equipment

a. Follow the instructions given in para-graph 9 for unpacking and checking the equip-ment.

b. Check the used or reconditioned equip-ment for tags or other indications of changesin wiring of the equipment. Note the changesin appropriate places in the technical manual.

c. Check all operating controls for ease ofoperation.

d. Install the equipment, if necessary, asdirected in paragraph 10.

1 1

Figure 7. Tape threading diagram.

12

CHAPTER 3

OPERATION

Section I. OPERATION UNDER USUAL CONDITIONS

13. Preliminary Procedurea. Install the equipment (par. 10).b. Turn the editing knobs (fig. 7) on the

supply reel and the take-up reel spindlescounterclockwise and lift the knobs off thespindles.

c. Insert the hub adapter (located on thespindles into the reel before mounting; do notmount the reels on the hub adapters. Mount afull reel of tape on the supply reel (left-hand)spindle, and mount an empty take-up reel onthe take-up (right-hand ) spindle (fig. 7).

d. Place the editing knobs on the reels; besure that the pin on the spindle is engaged inthe hole in the editing knob; push the knob.Tighten the knob by turning it clockwise.

e. Open the gate on the sound head assemblyby pulling the gate knob (fig. 7).

f. Remove and discard the adhesive tapefrom the end of the recording tape.

g. Thread the tape in the path indicated infigure 7. Insert the end of the tape in one ofthe slots in the take-up reel. Turn the take-upreel 2 or 3 turns counterclockwise to wind thetape onto the reel and also to remove any slackin the tape.

h. Close the tape gate by pushing the gateknob. This will assure that the tape fits againstthe recorder-reproducer, and erase heads in thesound head assembly.

14. Microphone Recording(fig. 8)

During the recording operation, intelligencestored on the tape will be erased (removed)before new intelligence is recorded. To recordwith a microphone, proceed as follows:

a. Connect and prepare the equipment foroperation (par. 10 and 13).

b. Move the 7½ 15" switch on the recorder-reproducer (fig. 7) to the desired speed.

c. Turn the EQUALIZATION switch of theamplifier (fig. 12) to the 7½ I.P.S. or the 15I.P.S. position to correspond with the settingindicated in b above.

d. Move the ON-OFF switch on the recorder-reproducer to the ON position.

e. Press the PLAY switch on the recorder-reproducer.

f. Press the RECORD switch on the ampli-fier; the RECORD INDICATOR should glow.

g. Talk into the microphone in a normalmanner. Adjust the RECORD LEVEL control(fig. 12) until the meter indicates 100 on soundpeaks. A decrease in distance between the op-erator’s mouth and the microphone may causethe meter needle to indicate above 100. If thisshould happen, increase the distance ratherthan reset the RECORD LEVEL control.

h. When the recording is completed, pressthe STOP switch on the recorder-reproducer.

i. To start recording again, repeat the in-structions given in e, f and g above.

j. If a recording requires more than onereel of tape, have additional reels for immedi-ate use to minimize loss of desired recordedintelligence. Identify each reel to assure con-tinuity of playback.

k. If a playback is desired to establish a re-cording continuity, follow the playback opera-tion procedures outlined in paragraph 18.

l. If two or more programs or sets of intelli-gence are to be recorded on the same tape, besure that a dead space (no recorded informa-tion ) is provided between the two programsor sets of intelligence.

1 3

Figure 8. Equipment setup for microphone recording.

14

m. If it is desired to record intelligence onthe second track of the tape, remove the edit-ing knobs on the reels, remove the reels andre-install the reels in the following manner:

(1)

(2)

(3)

Turn the full reel (the reel of tapejust recorded) upside down.Place the full reel on the supply spin-dle (left-hand), and place the emptyreel on the take-up reel spindle(right-hand).Thread the tape (par. 13) and repeatinstructions given in e, f, g, and habove.

n. Stop the equipment as directed in para-graph 23.

15. Telephone Line Recording(fig. 9)

To record a telephone conversation, proceedas follows:

a. Install the recorder-reproducer set andconnect Tone Warning Group OA-145/GT asdescribed in paragraphs 10 and 11 respectively,and as shown in figure 9.

b. Operate Tone Warning Generator Con-trol C-638/GT as directed in TM 11–2088.

c. Insert the connector on the end of theheadset cord in the EARPHONES jack on theamplifier panel (fig. 12).

d. Listen in with the headset. When theconversation begins, press the PLAY and thenthe RECORD switches on the recorder-repro-ducer and on the amplifier; the RECORD indi-cator of the amplifier should glow. Adjust theRECORD LEVEL control until the vu meterindicates between 60 and 100 (-3 to 0 decibels(db)). The vu meter should indicate 100 onsound peaks.

e. At the end of the conversation, press theSTOP switch on the recorder-reproducer.

f. Continue to listen in with the headset. Ifthe telephone conversations are frequent, pro-vide about ½ minute of dead tape betweenrecordings.

g. At the end of the recording, move theON-OFF switch on the recorder-reproducer tothe OFF position. All pilot lamps should extin-guish.

h. If no further recordings are anticipated,stop the recorder-reproducer set (par. 23).

16. Program Line Recording(fig. 10)

To record from a program line, proceed asfollows:

a. Install and connect the equipment (par.10 and 11).

b. Make the necessary connections for moni-toring (par. 17).

c. Thread the tape (par. 13).d. Move the ON-OFF switch to the ON posi-

tion. Allow 5 minutes for warm up.c. Monitor the incoming program using the

headset or loudspeaker (par. 17). Adjust theRECORD LEVEL control until the vu meterindicates 100 on sound peaks.

f. When ready to record, press the PLAYswitch on the recorder-reproducer and theRECORD switch on the amplifier.

g. If the tape runs out, reverse the tape(par. 14m) and record on the second track.

h. At the end of the recording period, pressthe STOP switch on the recorder-reproducer.Stop the equipment (par. 23).

17. Monitoring Operation

Monitoring a recording may be accomplishedby using the headset with the amplifier or byusing the headset or the loudspeaker with theaudio amplifier. The necessary connections antiswitch positions required for preparing therecorder-reproducer set for monitoring arecovered in a below. The monitoring operaiicmis outlined in b below.

a. Providing for Monitoring.(1) Amplifier. Proceed as follows:

(a)

(b)

(c)

Insert the headset plug in the EAR-PHONES jack on the amplifierpanel (fig. 12).Move the LINE TERMINATIONswitch to the OFF position.Monitor the recording (par. 15 or16) as described in b below.

(2) Audio amplifier. Proceed as follows:(a) Open the access door at the side of

audio amplifier carrying case andcheck to see that the female connec-tor at the end of the interconnect-ing power cable is connected to themale connector on the rear panel ofthe audio amplifier. Also check to

1 5

16

Figure 9. Equipment setup for telephone recording.

(b)

(c)

see that the male connector at theother end of the interconnectingpower cable is inserted in the fe-male connector at the rear of theamplifier chassis.Insert the headset plug in thePHONES jack on the audio ampli-fier panel (fig. 13).Turn the function switch to thePHONES position and monitor therecording as described in b below.To monitor, using the self-containedloudspeaker, turn the functionswitch to the SPEAKER position.To use the headset and the loud-speaker, turn the function switch tothe SPEAKER PHONES position.

b. Monitoring a Recording. The followingmonitoring procedure applies to either theamplifier (a(1) above ) or the audio amplifier(a(2) above). Proceed as follows:

(1)

(2)

(3)

(4)

(5)

Listen to the recording for quality.Turn the METER SELECTOR switchto the RECORD LEVEL position.If required, adjust the RECORDLEVEL control to keep the vu meterindicator from passing the 100 markon the sound peaks.

Turn the METER SELECTOR switchto the BIAS position, The vu metershould indicate 100.

Turn the METER SELECTOR switchto the ERASE position. The vu metershould indicate 100.

Adjust the PLAYBACK LEVEL orMONITOR LEVEL control (fig. 12and 13), depending upon which ampli-fier is being used, for comfortablesound volume m the ‘headset. For con-trol of loudspeaker volume, adjust theMONITOR LEVEL control only.

Return the METER SELECTORswitch to the RECORD LEVEL posi-tion and adjust the RECORD LEVELcontrol as required during the record-ing to keep the vu meter indicatorfrom passing the 100 mark on soundpeaks.

18. Reproducing or Playback Operation(fig. 11)

To playback a recording, proceed as follows:

a. Connect and prepare the equipment (par.10 and 13).

b. Move the METER SELECTOR switch tothe PLAYBACK LEVEL position (fig. 12).

c. Set the PLAYBACK LEVEL control tothe 8 position. This setting may have to bechanged during operation.

d. Connect a headset to the PHONES (fig.13) or EARPHONES (fig. 12) jack. If theheadset is connected to the PHONES jack onthe audio amplifier, move the function switchto the PHONES position. If the information iSto be played back for a small audience, movethe function switch to the SPEAKER or theSPEAKER PHONES position.

e. To serve a large group of listeners lo-cated at some distance from the equipment,use a suitable external loudspeaker (par. 4).Insert the external loudspeaker plug in theEXTERNAL SPEAKER jack on the audioamplifier, and turn the function switch toeither the SPEAKER or the SPEAKERPHONES position. This will disconnect theinternal loudspeaker.

f. Be sure that the recorded reel of tape isin place on the supply reel spindle.

g. Move the ON-OFF switch to the ONposition; wait about 5 minutes. When readyto play back, press the PLAY switch on therecorder-reproducer.

h. To select the portion of tape to play,wind or rewind the tape for the desired infor-mation (par. 19 and 20). After reaching theapproximate location of the desired material onthe tape, use the editing knobs (fig. 7) torotate the reels as required to reach the exactlocation.

i. Adjust the sound level by rotating thePLAYBACK LEVEL control to the desiredsetting.

j. When finished with the playback opera-tion, press the STOP switch on the recorder-reproducer. Stop the equipment (par. 23).

17

Figure 10. Equipment setup for program line recording.

1 8

19. Rewinding Operation

To rewind the tape, proceed as follows:a. At the end of a recording or playback

operation, press the STOP switch on therecorder-reproducer.

b. Grasp the gate knob on the sound headassembly (fig. 7) and open the gate.

c. Press the REWIND switch. One minuteis required to rewind a full 10 ½-inch reel. Theequipment will shut down when the end of thetape comes off the take-up reel and frees theautomatic switch arm and tape guide (fig. 7).

d. If a full tape rewind is not necessary,press the STOP switch and close the gate onthe soundhead after rewinding the tape to theapproximate location; use the editing knobs(fig. 7) to find the desired recording. Record-ing or reproducing is not possible unless thegate is closed.

e. If the tape breaks during rewind, theequipment will stop. Splice tape as directed inparagraph 22.

20. Fast Forward Operation

To wind the tape quickly, proceed as follows:a. Grasp the gate knob on the soundhead

assembly (fig. 7), and open the gate.b. Press the WIND switch. One minute is

required to wind a full 10½ inch reel of tape.c. When the desired portion of tape becomes

available, press the STOP switch. Close thegate and use the editing knobs to locate theexact place on the tape.

d. If the tape breaks during the fast windoperation, the equipment will stop. Splice thetape as directed in paragraph 22.

21 Public Address Operation(fig. 11)

To use the recorder-reproducer set as a publicaddress set, proceed as follows:

a. Connect the equipment as directed in para-graphs 10 and 13.

b. Connect the microphone to the INPUTconnector on the amplifier (fig. 12).

c. Move the INPUT SELECTOR SWITCH tothe MIC position.

d. Adjust the MONITOR LEVEL control onthe audio amplifier to the 5 position. This set-ting may have to be changed later.

e. Move the METER SELECTOR switch to theRECORD LEVEL position.

f. Move the function switch on the audioamplifier to the SPEAKER position.

g. Connect a suitable external loudspeaker(par. 4) to the EXTERNAL SPEAKER jackon the audio amplifier.

h. Move the ON-OFF switch to the ONposition; wait about 6 minutes.

i. Speak into the microphone. Adjust theMONITOR LEVEL control on the audio ampli-fier for the desired level of sound. If the howl-ing (acoustic feedback) occurs, either thespeech delivery is too loud, the setting of theMONITOR control is too high, or the micro-phone is not located correctly. Correct thiscondition by relocating the loudspeaker ormicrophone.

j. At the end of the delivery, stop the equip-ment as directed in paragraph 23.

22. Splicing Tape

Splice recording tape as follows:a. Place the two loose ends together glossy

side up; be sure to overlap the ends about½ inch and cut across the ends at a 46° angle.

b. Place the ends of the tape on a flat sur-face, with the glossy side of the tape up.

c. Butt the ends together and secure themwith splicing tape. or ordinary gummed cellu-lose (Scotch) tape. Be sure that the splicingtape is placed parallel to the cut ends, and thenpress firmly.

d. Trim the splicing tape, so that the splicedjoint is slightly narrower than the tape. Thiswill prevent jamming of the tape when thetape is pulled past the sound heads.

23. Stopping Operation

To stop the equipment, proceed as follows:a. Press the STOP switch on the recorder-

reproducer (fig. 7).b. Move the ON-OFF switch on the recorder-

reproducer to the OFF position.c. Turn the RECORD LEVEL and the PLAY-

BACK LEVEL controls to the 0 position. Alsoturn the MONITOR LEVEL control to the 0position.

d. Remove the power cable plug from thepower receptacle if the equipment is to be out ofservice for a long period of time.

1 9

Figure 11. Equipment setup for playback

2 0

Section Il. OPERATION UNDER UNUSUAL CONDITIONS

24. GeneralThe operation of the recorder-reproducer set

may be difficult in regions where extreme cold,heat, humidity and moisture, or sand condi-tions prevail. Procedures that minimize theeffects of these unusual climatic conditions aregiven in paragraphs 25, 26, and 27.

25. Operation in Arctic ClimateExtreme cold followed by moisture-laden

warmth causes condensation to form on andin the equipment. A high B voltage across wetterminals may cause damaging current pathsto form. Dry the equipment thoroughly. Coverthe equipment immediately after use to retainequipment operating temperature for a longertime.

26. Operation in Desert ClimatesTo prevent equipment failure in areas sub-

ject to extremely high temperatures, low hu-midity, and excessive sand, dust, and dirt,operate the equipment in a sandproof shelter.When not in use, keep the equipment coveredto keep out sand, dirt, and dust.

27. Operation in Tropical Climates

In damp, tropical climates of high relativehumidity, condensation occurs on and in theequipment whenever the temperature of theequipment is sufficiently lower than the warm,moisture-laden air. To minimize this condition,cover the equipment immediately after use toretain the dry heat. Turn the equipment ondaily to generate enough dry heat to insurefreedom from the effects of moisture andfungus growth.

2 1

Figure 12. Amplifier, front and rear panels.

Figure 13. Audio amplifier, front and rear panels.

2 2

CHAPTER 4

ORGANIZATIONAL MAINTENANCE

Section 1. CONTROLS AND INSTRUMENTS

Note. This section describes, locates, and illustrates the operating controls and instruments.

28. Controls and Indicators and Their Uses(fig. 7, 12 and 13)

The following charts list the controls andindicators on the front panels of the compo-nents of the recorder-reproducer set and de-scribe the function of each.

a. Amplifier (fig. 12).

Control

RECORD INDICATOR

RECORD switch

EQUALIZATION switch

Vu meter

LINE TERMINATIONswitch

Function

Neon lamp; indicates thatequipment is ready to re-cord.

When pushed, arranges cir-cuits for the recordingfunction, causes the REC-ORD INDICATOR to lightand starts tape movement(if the PLAY (b below)switch has been pressedfirst).

Rotary switch; increases thehigh frequency response ofthe recording amplifier for7 ½-ips operation.

Indicates recording level,playback level, bias leveland erase-oscillator current

as selected by operation ofthe METER SELECTIONswitch.

In the OFF position, providesfor better impedance mat.thing between the ampli-fier and audio amplifier.

In the ON position, permitssuitable disconnection ofaudio amplifier from amp-lifier by providing substi-tute loading of the playback amplifier output.

C o n t r o l

METER SELECTORswitch

ON-POWER

RECORD LEVELcontrol

INPUT SELECTORSWITCH

PLAYBACK LEVELcontrol

Func t i on

Four-position switch used asfol lows: PLAYBACKLEVEL: indicates theplayback amplifier output.RECORD LEVEL: indi-cates recording amplifieroutput. BIAS: indicatesbias level. ERASE: indi-cates erase-oscillator cur-rent.

Pilot light; indicates poweris connected to the ampli-fier and audio amplifier.

Adjusts the signal level forthe recording operation.

Four-position switch; pro-vides for the followingtypes of input:MIC. for microphone;BRIDGE for high impe-

dance;600 BAL. for 600 ohms bal-

anced line;600 UNBAL. for 600 ohms

unbalanced line.

Adjusts the playback signallevel.

b. Recorder-Reproducer (fig. 7).

Control

ON-OFF switch

STOP switch

Function

Opens and closes the ac powercircuit for the entire equip-ment.

Energizes the brake circuit;stops rotation of the take-up and the supply motors;closes the circuit to thesolenoid to release the cap-stan roller; stops tapemovement.

23

Control Function

PLAY switch Closes the ac circuit to thedrive motors for playbackoperation; releases thebrake solenoids; closes thecircuit to engage the cap-stan roller; starts tapemovement.

REWIND switch Closes the ac circuit to thesupply-reel motor and re-leases the brakes to permitrewind operation.

WIND switch Closes the ac circuit to thetake-up motor and releasesthe brakes to permit fastforward operation.

7½ -15", switch Selects either 7 ½-ips or 15-ips speed of the capstanmotor, to provide for slow-er or faster tape move-ment.

Automatic switch arm Energizes the brake circuitto stop rotation of the take-UP and supply motor whenthe tape breaks. Also openscircuit of solenoid to re-lease the capstan roller.

c. Audio Amplifier (fig. 13).Control Function

Function switch Selects the desired operationfor monitoring public ad-dress;

PHONES for headset opera-tion;

SPEAKER-PHONES forspeaker and headset op-eration simultaneously;

SPEAKER for loudspeakeroperation.

POWER pilot lamp Indicates that ac power isconnected to the audioamplifier.

MONITOR LEVEL con- Varies the sound level of thetrol audio amplifier output.

29. Connectors and JacksThe following charts list the connectors and

jacks on the front and rear panels of the com-ponents of the recorder-reproducer set andindicate the function of each.

a. Amplifier (fig. 12).Item Function

INPUT connector Connects the input signal (to berecorded ) to the input of therecording amplifier input stage.

OUTPUT Connects the output of the play-connector back amplifier to the input of

a broadcast console or equiva-lent.

MONITOR jack Connects the output of the play-back amplifier to the input ofthe audio amplifier.

EARPHONES jack Connects the headset to the out-put of the playback amplifier.

Input power Provides a connection for theconnector power cable.

Monitor power Provides a connection for the in-connector terconnecting power cable.

b. Audio Amplifier (fig. 13).

Item Function

Input power Connects the input sc power toconnector the audio amplifier from the

amplifier.

Input signal Connects the input signal to theconnector audio amplifier from the amp-

lifier.

PHONES jack Connects the headset to the out-put of the audio amplifier.

EXTERNAL Connects an external loudspeakerSPEAKER jack to the audio amplifier output

for increased audience cover-age.

Section Il. ORGANIZATIONAL TOOLS AND EQUIPMENT

30. General 31. Organizational Maintenance Tools andOnly common hand tools or equipment Materials

(par. 31) are required for organizational The tools and materials listed below are usedmaintenance. The tools, parts, supplies, and in performing organizational maintenance ontest equipment necessary to perform organiza- the recorder-reproducer set. Gasoline will nottional maintenance are authorized appropriate be used as a cleaning fluid.publications. Alcohol Cleaning brush

24

Lint-free clothOil, Lubricating, Aircraft Instrument

(OAI)Sandpaper, #0000Cleaning Compound (Fed stock No.

7930-395-9542)

Section Ill. PREVENTIVE MAINTENANCE SERVICES

32. Definition of Preventive MaintenancePreventive maintenance is work performed

on equipment (usually when the equipment isnot in use) to keep it in good working order.Preventive maintenance minimizes equipmentbreakdowns and interruptions in service.

33. Use of Preventive Maintenance Forms(fig. 14 and 15)

a. DA Form 11-250.(1) DA Form 11-250 is a preventive

maintenance check list to be used bythe operator as directed by his com-mander.

(2) Items not applicable to the recorder-reproducer set are lined out on figure14. References in the ITEM block inthe figure are to paragraphs in thismanual which contain additionalmaintenance information pertinent tothe particular item.

b. DA Form 11-251.(1)

(2)

DA Form 11-251 is a preventivemaintenance check list to be used bya second echelon repairman as di-rected by his commander.Items not applicable to the recorder-reproducer set are lined out on figure13. References in the ITEM blockin the figure are to paragraphs in thismanual which contain additionalmaintenance information pertinent tothe particular item.

34. Preventive Maintenance Techniques

Recommended materials are listed in para-graph 31. Good preventive maintenance prac-tice requires that all fittings, screws, bolts, andnuts be tightened carefully to avoid strippingand other damage. It is important to removeCleaning Compound residue with a clean lint-free cloth. Use only Cleaning Compound on

Petrolatum, technical, (PET)Electron Tube Test Set TV–7/UMultimeter TS-297/UTool Equipment TS–113

electrical contacts, then wipe the contacts dry.Corrosion may be removed with #0000 sand-paper and Cleaning Compound.

Caution. Prolonged breathing of CleaningCompound fumes is dangerous. Be sure thatadequate ventilation is provided. CleaningCompound is flammable; do not use it near aflame.

a. Daily Items.(1)

(2)

(3)

(4)(5)

Check for completeness and generalcondition of the equipment. The com-ponents are listed in paragraph 5.Remove dirt and moisture from thecarrying cases, the front panels, con-trols, connectors, power receptacles,tape reels, tape, and all mechanicalparts on the panels.Inspect the seating of all. fuses of theamplifier and the audio amplifier.Inspect the seating of all pilot lamps.Inspect all operating controls forbinding, scraping, excessive looseness,and positive action.

b. Weekly Items.(1)

(2)

(3)

(4)

(5)

(6)

(7)

Check all connectors for chips, cracks,or corrosion.Inspect the exposed surfaces of bothcarrying cases for rust, corrosion, ormildew.Inspect the panels of all units forrust, corrosion, scratches, and dam-aged finishes.Inspect the power cable and othercables for kinks, breaks, deteriora-tion, and loose connections.Inspect the control knobs, switchknobs, and meter for looseness. Checkall exterior fastenings.Inspect the meter for damaged glassor case.Clean and inspect the microphone andheadset.

2 5

Figure 14. DA Form 11-250.

2 6

Figure 15. DA Form 11-251.

27

Figure 16. Tube location diagram, audio amplifier.

2 8

(8) Check and clean the capstan and cap-stan roller.

(9) Check the equipment for normal op-eration.

Caution: Disconnect all power(par. 23) from the recorder-repro-cer before performing the followingoperations. Upon completion, recon-nect power (par. 10) and check forsatisfactory recording and playbackoperation of the equipment (par. 14and 18).

c. Monthly.(1) Inspect all tubes (fig. 16 and 17)

tube clamps, and tube shields forproper seating.

(2) Inspect tubes for cracked envelopes.

(3)

Check tube sockets for cracks andloose connections.Inspect all potentiometers in the am-plifier and audio amplifier for dirtand loose connection.

(4)

(5)

(6)

(7)

(8)

(9)

(l0)

(11)

(12)(13)(14)(15)

Inspect all electrolytic capacitors inall three units for leaks or bulging.Inspect resistors for cracks, chipping,and discoloration.Tighten the mounting bolts for alltransformers in the amplifier andaudio amplifier.Inspect all transformers in the audioamplifier for evidence of overheating.Check the moistureproof and fungi-proof varnish for cracks and chipping,Check and clean the heads in thesound head assembly.Check the loudspeaker in the audioamplifier.Check all soldered connections in thethree chassis.Check all motors.Clean the fan of the capstan motor.Check and clean all chassis connectorsCheck all name plates, panel mark-ings, and chassis markings for legi-bility.

Section IV. LUBRICATION AND WEATHERPROOFING

35. LubricationThe only part of the recorder-reproducer set

requiring lubrication is the capstan motor.This should be done after 1,000 hours of op-eration; use oil (OAI). Under severe salt-airconditions, a very light protective coating ofpetrolatum (PET) may be applied to the con-tacts of the INPUT SELECTOR SWITCH,METER SELECTOR switch, and EQUALI-ZATION switch (fig. 12) of the amplifier, andthe function switch of the audio amplifier(fig. 13) after cleaning the contacts withCleaning Compound. Remove Cleaning Com-pound residue before applying the petrolatum.

36. Weatherproofinga. General. Signal Corps equipment, when

operated under severe climatic conditions, suchas prevail in tropical, arctic, and desert re-gions, requires special treatment and mainte-nance. Fungus growth, insects, dust, corrosion,salt spray, excessive moisture and extremetemperatures are harmful to most materials.

b. Tropical Maintenance. A special mois-tureproofing and fungiproofing treatment hasbeen devised which, if properly applied, pro-

vides a reasonable degree of protection. Thistreatment is explained in TB SIG 13, Moisture-proofing and Fungiproofing Signal CorpsEquipment, and TB SIG 72, Tropical Mainte-nance of Ground Signal Equipment.

c. Arctic Maintenance. Special precautionsnecessary to prevent poor performance or totaloperational failure of equipment in extremelylow temperatures are explained in TB SIG 66,Winter Maintenance of Signal Equipment andTB SIG 219, Operation of Signal Equipmentat Low Temperatures.

d. Desert Maintenance. Special precautionsnecessary to prevent equipment failure in areassubject to extremely high temperatures, lowhumidity, and excessive sand and dust are ex-plained in TB SIG 75, Desert Maintenance ofGround Signal Equipment.

37. Rustproofing and Paintinga. Rust and corrosion may be prevented by

touching up bared surfaces. Use #000 or #0000sandpaper to clean the surface down to thebare metal; produce a bright smooth finish.

Caution: Do not use steel wool; minuteparticles may enter the equipment and causeshorting or grounding of parts.

2 9

Figure 17. Tube location diagram, amplifier.

3 0

correded metal with Cleaning Compound and

b. If a touch-up paint job becomes neces- use sandpaper to complete the preparation ofsary, remove rust from the case by cleaning painting. Apply paint with a small brush. Use

only authorized paint.

Section V. TROUBLE SHOOTING AT ORGANIZATIONALMAINTENANCE LEVEL

38. General

a. The trouble shooting and repairs thatcan be performed at the organizational mainte-nance level (operators and repairmen) arelimited in scope by the tools, test equipmentand replaceable parts issued. Practical troubleshooting makes use of the senses in locatingsuch faults as burned-out fuses, broken cords,and defective tubes.

b. The paragraphs that follow in this sec-tion will help in locating the faulty circuit.

39. Visual Inspection

a. Failure of this equipment to operate prop-erly is caused usually by one or more of thefollowing faults:

(1) Worn, broken, or disconnected cordsor plugs.

(2) Burned-out fuses.(3) Defective tubes.(4) Defective motors or tape transport

mechanism.b. If the fault is not immediately apparent,

check as many of the items listed above as ispracticable before starting a detailed examina-tion of the equipment parts. If possible, obtaininformation from the equipment operator re-garding equipment performance when troubleoccurred.

40. Electron Tube Replacement ProcedureTo avoid excessive replacement of electron

tubes, follow the procedure outlined below.a. Inspect cables, connections, and the gen-

eral condition of the equipment before remov-ing electron tubes.

b. Isolate the trouble, if possible, to a par-ticular unit or section of the equipment.

c. If a tube tester is available, remove andtest one tube at a time. Substitute new tubesonly for those which are defective.

d. If a tube tester is not available, troubleshoot by the following tube substitutionmethod:

(1) Replace any suspected tubes, one at a

(2)

(3)

time, with new tubes. Note the socketsfrom which the original tubes wereremoved. If the equipment becomesoperative, discard the last tube re-moved.

Note. The erase-oscillator mayfunction with one tube and not an-other, even though both tubes arenew. If practicable, retain any re-moved tube until its condition ischecked by a suitable test instrument,Reinsert the remaining original tubes,one at a time, in the original sockets.If equipment failure occurs duringthis step, discard the last originaltube. DO NOT LEAVE A NEWTUBE IN A SOCKET IF THEEQUIPMENT OPERATORS SATIS-FACTORILY WITH THE ORIGI-NAL TUBE.If there is an insufficient number of spare tubes:

(a)

(b)

Substitute a new tube for an origi-nal tube. Similarly, check each orig-inal tube, in turn, until the equip-ment becomes operative.Often it is possible to remove atube from one section of the equip-ment without affecting the sectionbeing checked. In this case, troubleshoot the defective section usingthis tube as a substitute spare.

Note. If a replacement for a badtube becomes defective, check theadjustment and condition of’ com-ponent parts of the tube circuit.Otherwise, continued tube replace-ment will effect only temporary re-

31

pair and more serious troubles mayresult.

e. If tube substitution does not correct thetrouble, reinsert the original tubes in the origi-nal sockets before forwarding the defectiveequipment for higher echelon repair.

(1) As a general rule, discard tubeswhen:

(a) A test in a tube tester or otherinstrument shows that the tube isdefective.

(b) The tube defect is obvious. For

(2)

(3)

(4)

example, the glass envelope isbroken or a connecting prong orlead is broken.

Do not discard tubes merely becausethe tubes have been used for a speci-fied length of time. Satisfactory oper-ation in a circuit is the final proof oftube quality. The tube in use maywork better than a new one.Do not discard tubes merely becausethey fall on or slightly above the mini-mum acceptability value when checkedin a tube tester. It must be recog-nized that a certain percentage ofnew tubes fall near the low end ofthe acceptability range of the tubespecification and, therefore, start theiroperational life at a value fairly closeto the tube tester retention limit.These tubes may provide satisfactoryperformance throughout a long periodof operational life at the near limitvalue.Use special care in withdrawing aminiature tube from its socket. Donot rock or rotate the top of a minia-ture tube when removing it from asocket; pull it straight, out. The ex-ternal pin and the wire lead sealedin the glass base are two differentmetals which are butt-welded togetherwhere the pin appears to enter theglass. Rocking or rotating the tubebends the pins, this tends to breakthe weld or cause a resistance or in-termittent joint to develop.

(5) A preferred type electron tube, type5Y3WGTA, has been developed as adirect replacement for tube type 5Y3. This tube may be used interchange-ably in the amplifier and audio am-plifier power supply circuits.

41. Fuse Replacement

When replacing a defective fuse in eitherthe amplifier or the audio amplifier, be surethat the correct fuse is used. Use only a3-ampere fuse. Do not use a fuse rated higherthan 3 amperes, serious damage to the equipment may occur.

42. Trouble Shoot ing by Using Equipment Performance Check List

a. General. The equipment performancecheck list (par. 43) may help the operator tolocate trouble in the equipment. The check listindicates the item to be checked, the conditionsunder which the item is to be checked, thenormal indications and tolerances of correctoperation, and the corrective measures the op-erator can take. To use this list effectively,follow the items in numerical sequence.

b. Action or Condition. For some items, the information given in the Action or conditioncolumn consists of various switch and controlcheck settings which are made when the itemis checked. For other items, it represents anaction that must be taken to produce thenormal indication given in” the Normal indica-tions column.

c. Normal Indications. The normal indica-tions listed are the visible and audible signsthat the operator should observe after apply-ing the information given in the Action orcondition column. If the indications are notnormal, the operator should apply the recom-mended corrective measures.

d. Corrective Measures. Most of the correc-tive measures listed are those within the scopeof the operator. If the trouble cannot be cor-rected by the operator, trouble shooting by anexperienced repairman is necessary. However,if the tactical situation requires that theequipment be maintained, the operator mustkeep the set in operation as long as possible.

3 2

43. Equipment Performance Check List

a. Recording.

Item Item Action or Normal CorrectiveNo. condition Indications measures

1 Cable (microphone, inter-con- Connect all components. Connectors fit se- Apply proper pressurenetting and power). curely. on connectors.

2 Function switch, audio Operate to the PHONESamplifier. position.

3 MONITOR LEVEL control. Turn to a setting of 8.

4 RECORD LEVEL control. Turn to a setting of 5.

5 INPUT SELECTOR switch. Move to the MICposition.

P 6 METER SELECTOR switch. Move to the RECORDR LEVEL position.E 7 EQUALIZATION switch. Move to the 15 I.P.S.P position.AR 8 Headset. Connect to the EAR-

PHONES jack.AT 9 Supply reel. Install the supply reelO and adapter.

R 10 Take-up reel. Install the take-up reel.

Y 11 Tape gate. Open the gate.

12 Recording tape. Thread the tape. Tape tension closesautomatic safetyswitch S202.

13 LINE TERMINATION Move to the OFFswitch. position.

14 Tape gate. Close the gate.15 7 ½ -15” switch. Operate to the 15”

position.

16 Soundhead assembly. Check tape. Tape fits correctly in Turn the take-up reelthe soundhead as- to take up any slacksembly. in the tape.

17 ON-OFF switch. Operate to the ON Pilot lamps light, fila- Check the power cableposition. ments of the tubes and connections.

light.S Check the fuses

T (par. 41).

A Check the pilot lamp.R Check the tubesT (par. 40).

Check the ON-OFFswitch.

Replace the defectivefuses, tubes, andpilot lamps.

33

Item Item Action or Normal CorrectiveNo. condition indications measures

18 RECORD switch. Press the switch. RECORD INDI- Check the switch.CATOR lampglows. Check the lamp and

replace if defective.

19 PLAY switch. Press the switch. Tape moves from left Check all connections.to right (as viewedfrom front panel ). Check the switch.

Check the tape thread-ing (par. 13).

Check the gate.

20 RECORD LEVEL control, Talk into the microphone Vu meter indicates Check the microphone,vu meter. and adjust the 100 on loud sounds. cable and connector.

RECORD LEVEL Sound is heard incontrol. the headset. Check the meter.

Check the RECORDLEVEL control.

Check the headset andcable.

21 METER SELECTOR switch. While talking into the Recorded voice is Check the switch.microphone, operate heard in the head-the METER SELEC- set by the monitor.TOR switch to thePLAYBACK LEVELposition.

22 Headset. Connect to the PHONES Recorded tape is heard Check the headset.jack. in the headset.

Check the cables.

Check the PHONESjack.

23 PLAYBACK LEVEL While listening to the Vu meter indicates Check the PLAY.control. recorded sound, adjust 100 on peak of BACK LEVEL

the PLAYBACK sound. control.LEVEL control.

24 METER SELECTOR While talking into the Vu meter indicates Turn in equipment forswitch. microphone, operate 100, approximately. bias adjustment.

the METER SELEC-TOR switch to theBIAS position.

25 METER SELECTOR While talking into the Vu meter indicates Turn in equipment forswitch. microphone, operate 100, approximately. erase adjustment.

the METER SELEC-TOR switch to theERASE position,

26 STOP switch. Press the switch. Tape movement stops Check the switch.RECORD indicatoris extinguished. Check the RECORD

indicator,

27 Tape gate. Open the gate. Tape is removed from Check the gate.the contact with thesound head.

34

Item Item NormalNo.

Action or Correctivelndications condition measures

28 WIND switch. Press the switch. Tape winds quickly. Check the switch.Check the relays.

29 STOP switch. Press the switch. Tape movement stops. Check the switch.S Check the relays.T 30 REWIND switch. Press the switch, Tape rewinds quickly. Check the switch.O Check the relays.

P 31 STOP switch. Press the switch. Tape movement stops. Check the switch.32 ON-OFF switch. Move to the OFF posi- All pilot lights are

tion. extinguished.All motors stop.

b. Playback.

Item Item Action or NormalNo.

Correctivecondition indications measures

1 Cables, interconnecting Connect to proper con- Connectors fit prop- Apply properand power. nectors. erly. pressure.

2 Function switch, audio Move to the PHONESamplifier. position.

P 3 PLAYBACK LEVEL Turn to the 5 position.R control.E 4 METER SELECTOR Move to the PLAYBACKP switch. LEVEL position.A 5 LINE TERMINATION Move to the OFF posi-R switch. tion.

A 6 Headset. Connect to the EAR-

TPHONES jack.

Supply reel.O 7 Install a reel of recorded

tape.R 8 Take-up reel. Install the reel.Y 9 Tape. Open the gate, thread Tape fits correctly in Turn take-up reel

the tape, close the the soundhead as- take up any slackgate. sembly. Tape ten- the tape.

sion closes the auto-matic safety switch.

10 ON-OFF switch. Operate to the ON posi- Pilot lamps light, fila- Check the cables.tion. ments of the tubes Check the fuses.

glow. (par. 41)11 PLAY switch. Press the switch. Tape moves from Check the tape tram

supply reel. Sound port mechanism.is heard in the Check the headset,headset. Check the jack.

12 PLAYBACK LEVEL Listen to playback, ad- Meter indicates 100 Check the connectioncontrol; vu meter. just PLAYBACK on signal peaks. Check the meter.

LEVEL control. Check the control.13 Headset. Connect to the PHONES Playback is heard in Check the connector

jack. the headset.14 Function switch audio Turn to the SPEAKER Sound is heard in the Check the loudspeaker

amplifier. PHONES position. loudspeaker,15 External loudspeaker. Connect to the EX- Sound is heard in the Check the loudspeaker

TERNAL SPEAKER external loud-jack. speaker.

16 Same as items 31 and 32in a above.

35

Figure 18.

Figure 18. Block diagram of recording circuit.

3 6

CHAPTER 5

THEORY

44. General

The recorder-reproducer set has the follow-ing major interrelated components; recorder-reproducer, amplifier, and audio amplifier(fig. 48, 49, and 50).

a. Recorder-reproducer. The recorder-repro-ducer drive system consists of a two-speed cap-stan motor (B202), a take-up reel motor(B201), and a supply-reel motor (B203). Thesound head assembly consists of the erasehead (E203), the recorder head (E202), andthe reproducer head (E201). A half-wavepower supply circuit consists of a seleniumrectifier (CR201) and a filter capacitator(C203). The power supply delivers direct-current (dc) voltage for energizing relaysK201, K202, and K203, solenoids L201, L202,and L203 of the recorder-reproducer, and K101of the amplifier.

b. Amplifier. The amplifier consists basicallyof a power supply circuit, a recording amplifiercircuit, a playback amplifier circuit, an erase-oscillator circuit, and the volume level (vu)meter circuit.

(1)

(2)

Power supply circuit. The powersupply consists of full-wave rectifierV108 ( 5Y3GT) and a filter circuit.The power supply delivers dc voltagefor the B+ and screen circuits andac and dc filament voltages for thetubes in the amplifier and erase-oscil-lator circuits. (Filaments of tubesV101, 104, and V105 are dc fed tominimize hum pick-up. )Recording amplifier circuit. The re-cording amplifier consists of fourresistance-coupled amplifier stages,tube V101 (5879 pentode tube), tubeV102A (one-half of dual triode

(3)

(4)

(5)

6SN7), tube V102B (the other half),tube V103 (6C5 triode tube), and anequalizer circuit consisting of a re-sistance-capacitance network to cor-rect the frequency response of theamplifier. The output of the recordingamplifier is connected to the recorderhead in the amplifier group.Playback amplifier circuit. The play-back amplifier consists of three resist-ance-coupled amplifier stages, tubesV104 and V105 (5879 pentode tubes)and tube V106 (6C5 triode tube). Theoutput of the playback amplifier isfed to OUTPUT connector P102,EARPHONES connector J104, andMONITOR connector J105.Erase-oscillator circuit. The erase-oscillator circuit is a 65-kilocycle (kc)oscillator that consists of tube V107(6SN7 dual triode) and a tuned tankcircuit. The oscillator voltage erasesunwanted recordings and provides ahigh frequency magnetic bias thatimproves the quality of the recording.Volume level (vu) meter circuit. Vol-ume level meter M101 is connectedacross the output terminals of theplayback amplifier. Meter M101 indi-cates the level of sound during record-ing and playback operation. The meteris used also to indicate bias and erasecurrents.

c. Audio Amplifier. The audio amplifier con-sists of a power supply circuit, a voltageamplifier-phase inverter circuit, a push-pullpower-amplifier circuit, and a loudspeaker. Theaudio amplifier is used for monitoring and forpublic address set operation.

37

(1)

(2)

(3)

Power supply circuit. The power sup-ply circuit consists of full-wave rec-tifier tube V301 (5Y3GT) and a filtercircuit. The power supply delivers dcvoltages for the B+ and screen cir-cuits and ac voltages for the filamentsof the tubes in the audio amplifier.Voltage amplifier-phase inverter cir-cuit. The voltage amplifier-phase in-verter circuit consists of tube V302(12AX7 dual triode). The tube de-livers signal voltage for the push-pullpower-amplifier stages.Push-pull power-amplifier circuit. Thepower-amplifier circuit consists oftubes V303 and V304 (6V6GT pen-tode) connected in push-pull. Thetubes deliver audio power to the loud-speaker.

45. Recording Block Diagram(fig. 18)

a. The signal paths through the soundrecorder-reproducer set with the equipmentoperating as a recorder are as follows:

(1)

(2)

(3)

(4)

(5)

The input signal from either themicrophone or the incoming line isfed into input amplifier tube V101through the contacts of INPUT SE-LECTOR SWITCH S101, which isused to select the correct circuit forthe type input signal supplied.The amplified output of tube V101 isfed to amplifier tube V102A throughRECORD LEVEL control R110 whichis used to control the level of thesignal fed to tube V102A.The amplified signal is fed throughthe equalization circuit to amplifiertube V102B, amplified again, and thenfed to recording amplifier tube V103.The output of tube V103 is connectedto the recorder head in the soundhead assembly through contacts 6 and7 of record relay K101.During the recording, the output oferase-oscillator tube V107 is fedthrough an interconnecting cable toerase head E201 in the sound headassembly.

b. For monitoring purposes, a portion ofthe recording amplifier is fed to, and amplifiedby, the playback amplifier as follows:

38

(1)

(2)

(3)

(4)

A portion of the output signal of tubeV102A is fed to voltage amplifier tubeV105 through the contacts of METER SELECTOR switch S102.The amplified output of tube V105(fig. 19) is fed to output amplifiertube V106, and then to OUTPUT con-nector P102, EARPHONES jack J104,and MONITOR jack J105 (fig. 19).A portion of the output of tube V106is fed back to the cathode of tubeV105 as a negative feed-back voltage.Tube V105 output is connected

(5)

through METER SELECTOR switchS102 to EARPHONES jack J104, toOUTPUT connector P102, or to the audio amplifier through a connectionto MONITOR jack J105.LINE TERMINATION switch S106is used to close a circuit to load theplayback amplifier output when usinga headset with other than a 600-ohmimpedance or when the audio ampli-fier is not connected to the amplifier.

46. Playback Block Diagram(fig. 19)

The signal paths with the equipment operated as a reproducer, are as follows:

a. The recorded signal from the reproducerhead in the sound head assembly is fed intoplayback pre-amplifier tube V104.

b. The output of tube V104 is fed to tubeV105 through. an equalization circuit andthrough the PLAYBACK LEVEL control,which regulates the strength of the signal fedinto voltage amplifier tube V105.

c. The signal then follows the same pathdescribed in paragraph 45b. In this mode ofoperation, the volume level (vu ) meter is con-nected across the output of tube V106 to indi-cate the level of sound being played back.

47. Audio Amplifier, Block Diagram(fig. 20)

The signal paths, with the audio amplifierconnected to the output of V106 for monitoringpurposes, are as follows:

a. The signals from OUTPUT connectorP102 are fed to amplifier phase-inverter tubeV302 through MONITOR INPUT connectorJ303.

Figure 19. Block diagram of playback circuit.

Figure 20. Block diagram of audio amplifier.

3 9

b. The signal is amplified and inverted inphase.

c. The amplified and phase-inverted signalsare applied to push-pull, power-amplifier tubesV303 and V304.

d. The output of the audio amplifier is fedthrough function switch S301 to internal loud-speaker LS301 (or to an external loudspeakerthrough connection to EXTERNAL SPEAKERjack J301) or to a headset through connectionto PHONES jack J302. Connection of an ex-ternal speaker in EXTERNAL SPEAKER jackJ301 disconnects the internal loudspeaker.

e. A portion of the output is fed back to thecathode of tube V302 as a negative feed-backvoltage.

48. Recorder-reproducer(fig. 36 and 37)

The recorder-reproducer contains the tape-transport mechanism, necessary tape-transportcontrols, the soundhead assembly, and a powersupply circuit.

a. Tape-transport Mechanism. The tape-transport mechanism consists of two-speedcapstan motor B202 and tape drive assembly,supply-reel motor B203, take-up reel motorB201, and the necessary tape guides, brakes,solenoids, and relays.

b. Controls. The controls consist of ON-OFF switch S203, STOP switch S201, PLAYswitch S206, REWIND switch S207, WINDswitch S205, 7½’’–15” switch S204, and auto-matic shut-off arm switch S202.

c. Soundhead Assembly. The soundhead as-sembly contains the erase head, the recorderhead, the reproducer head, the tape guides,and connector P204.

d. Power Supply. The power supply circuitconsists of a selenium rectifier and a filtercircuit which supplies dc voltage for operatingthe relays, the brakes, and the solenoids.

49. Recording or Playback Circuit(fig. 49 and 50)

a. With the tape threaded properly and theequipment for recording (par. 14) or play-back (par. 18), 115 volts ac is connected tothe windings of all motors and to the input ofthe recorder-reproducer power supply. ResistorR202 is connected in series with the windingsof take-up motor B201 through contacts ofrelay K201. Resistor R203 is connected in

40

series with the winding of supply motor B203,also through contacts of relay K201. The cir-cuit of two-speed capstan motor B202 is closed through the contacts of 7½’’-l5” switch S204.Capacitators C201, C202, and C204 are motorstart capacitators used to provide adequatemotor starting torque.

b. With PLAY switch S206 closed, the dccircuit to the winding of relay K201 is closedthrough contacts 3 and 4 of relay K202. RelayK201 closes and completes the ac circuit tosupply motor B203 through contacts 5 and 4of relay K201, and through R203. The actionalso completes the ac circuit to take-up” motorB201 through contacts 12 and 9 of relay K201and tapped resistor R202. Resistors R202 andR203 reduce the voltage to the windings of themotors to reduce the starting torque.

c. Solenoids L201 and L203 of brakes O 201and O 203 respectively are connected to oneside of the dc circuit through the closed con-tacts of automatic safety switch S202 andpush-to-open STOP switch S201. The dc circuitis closed through contacts 6 and 7 of relayK201. Solenoid L202 of drive roller O 202 isconnected to the low side of the dc circuit andthe circuit is closed through contacts 11 and2 of relay K201 and contacts 3 and 4 of relay K202. With the brake solenoids energized, thebrakes are released and the motors are free torotate. With drive roller solenoid L202 ener-gized, the pressure roller assembly is engagedand presses the tape between the pressureroller and the tape capstan drive.

d. The action of the capstan drive and thepressure roller feeds the tape from the supplyreel onto the take-up reel. Supply motor B203drives the supply-reel spindle and developsenough drag on the tape to provide the correcttensioning of tape against the automatic switcharm (of switch S202); the take-up motordrives the take-up reel spindle to prevent tapespilling.

e. During recording, the tape is pulled pastthe erase head, the recorder head, and thereproducer head in successive order. Informa-tion, previously recorded on the tape, is erasedby the magnetic field of the erase head.

f. The power supply circuit consists ofselenium rectifier CR201, limiting resistorR201, and filter capacitor C203, The ac input(115 volts) is rectified by CR201 and filtered

by R201 and C203. The output voltage of thepower supply is 115 volts dc with full load.

50. Fast Rewinding Circuit(fig. 50)

a. With the tape threaded properly and theequipment operated for rewinding (par. 19),115 volts ac is connected to the winding ofsupply motor B203 and to the input of therecorder-reproducer power supply. SolenoidsL201 and L203 of brakes O 201 and O 203 areenergized and the brakes are released, SolenoidL202 of drive roller O 202 is not energizedand the pressure roller therefore is not pressedagainst the tape capstan drive thus releasingthe tape metering action. Supply motor B203rapidly rewinds the tape onto the supply reel.

b. One side of the 115-volt ac line is con-nected to the input of the selenium rectifier,and the other side of the line is connected tothe low side of the rectifier circuit. The 115-volt dc output of the rectifier is connected tothe coil of relay K202 through contacts ofsafety switch S202, STOP switch S201, andREWIND switch S207. The circuit, whenclosed through contacts 8 and 7 of relay K201,energizes relay K202 and applies 115 volts dcto the coil of relay K201 through holding con-tacts 9 and 12 of relay K202.

c. Ac power is now connected to the wind-ing of supply motor B203, through contacts 3and 4 of K203 and 4 and 5 of relay K202.

d. Solenoids L201 and L203 of brake O 201and O 203 are connected to the 115-volt dcoutput of the rectifier and the circuit is com-pleted through contacts 11, 2, and 4 of K202.

51. Fast Winding Circuit(fig. 50)

a. With the tape threaded properly and theequipment operated for fast wind operation(par. 20), 115 volts ac is connected to thewinding of take-up motor B201 and to theinput of the selenium power supply. RelaysK203 and K202 and solenoids L201 and L203of brakes O 201 and O 203 are therefore ener-gized with dc; solenoid L202 of O 202 is notenergized however. Take-up motor B201 rap-idly rewinds the tape onto the take-up reel.

b. The output of the rectifier is connectedto the coil of relay K203 through automaticsafety switch S202, STOP switch S201, closedcontacts 8 and 7 of relay K202, and WIND

switch S205. The circuit is completed throughcontacts 8 and 7 of K201, thus energizing relayK203. This applies 115 volts dc to the coil ofrelay K203 through holding contacts 9 and 12of relay K203. With relay K203 energized, 115volts dc is also applied to the coil of relayK202 through contacts 7 and 6 of relay K203.The circuit to the coil of relay K202 is closedthrough contacts 8 and 7 of relay K202, ener-gizing the relay. With relay K202 energized,115 volts dc is applied to holding contacts 9and 12 of relay K202.

c. Ac power is connected to take-up motorB201 through the contacts of ON-OFF switchS203 and capacitor C201. The circuit is com-pleted through contacts 5 and 4 of relay K203and contacts 5 and 4 of relay K202.

d. Solenoids L201 and L203 of brake O 201and O 203 are connected to the 115-volt dcoutput of the rectifier and the circuit is com-pleted through contacts 11, 2, and 4 of relayK202.

52. Recording Input Circuita. Microphone (fig. 21). With the micro-

phone connected to INPUT connector P101,and INPUT SELECTOR SWITCH S101 oper-ated to the MIC. position, incoming signalsfrom the microphone are connected across theprimary of transformer T101 through contacts8 and 9 of the rear section of switch S101, and8 and 6 of the front section of switch S101.Signal information is induced into he secon-dary of transformer T101 and then to pin 1(control grid) of tube V101. Resistor R160provides a low-impedance path to ground toreduce hum level.

b. Bridging input (fig. 22). A bridginginput circuit is a high-impedance circuit con-nected across a program line. The high im-pedance is used to prevent excessive loadingof the line. The incoming signal at INPUTconnector P101 is connected across a balancedinput circuit consisting of resistors R102 andR103, through contacts 8 and 10 of the rearsection, and 6 and 9 of the front section ofswitch S101. The signal from the program lineis applied to the primary of T101 from thejunction of voltage divider resistors R101 andR160, and the circuit is closed from trans-former T101 to the junction of voltage dividerresistors R104 and R159, through contacts 2and 3 of the rear section of switch S101.

4 1

Resistors R159 and R160 are also used to pro-vide the correct impedance loading for theprimary of transformer T101.

c. Balanced Input (fig. 23). With INPUTSELECTOR SWITCH S101 in the 600 BAL.position and a signal source connected toINPUT connector P101, the input circuit issimilar to that for bridging, except that re-sistors R105 and R106 are connected acrossthe input. The junction of the resistors isgrounded through contacts 2 and 3 of the frontsection of switch S101.

d. Unbalanced Input. This circuit is thesame as the circuit for balanced input exceptthat the ground connection at the junction of R105 and R106 is removed.

53. Recording Amplifier and Erase-oscillatorcircuit

(fig. 24 and 49)a. Genera/. The input signal to the amplifier

is taken from the microphone input, the tele-phone, or a program line. The signal is ampli-fied successively by input amplifier tube V101,equalizing amplifier tube V102A, voltage am.plifier tube V102B, and recording amplifiertube V103. The output of the recording ampli-fier is fed to the recorder head in the soundhead assembly. The erase-oscillator output isconnected to the erase head in the sound headassembly.

b. Input Amplifer V101. The input signaldeveloped across the secondary of transformerT101 is fed to the control grid of tube V101,and the amplified output developed across plateload resistor R108 is coupled out to tube V102Acontrol grid through capacitor C103. Platevoltage for tube V101 is taken from the junc-tion of resistor R161 and capacitor C120C anddropped by resistors R163 and R108. Resistor

Figure 21. Microphone input circuit, simplifiedschematic diagram.

R163 and capacitor C104A form a decoupling filter and prevent the ac output of tube V101from reaching the power supply circuit. Screenvoltage for tube V101 is taken from the junc-tion of resistors R163 and R108 and applied tothe screen through voltage dropping resistorR109. Capacitor C102 is a screen bypass ca-pacitor. Cathode bias is developed acrossresistor R107, and maintained at a constantlevel by capacitor C101.

c. Equalizing Amplifier V102A. The outputsignal of tube V101 smears across RECORD

Figure 22. Bridging input circuit, simplifiedschematic diagram.

LEVEL control R110 and a portion of thesignal is fed to the control grid of V102A,which is connected to the center arm of theRECORD LEVEL control. The amplified sig-nal output across plate load resistor R112 iscoupled out to tube V102B control grid throughcapacitor C106. Plate voltage for tube V102Ais taken from the junction of resistors R158and R137. Resistor R158 and capacitor C104Cform a decopling filter and decouple the out-put of V102A from the power supply circuit.Cathode bias is developed across cathode re-sistor R111 and filtered by capacitor C105.

Figure 23. Balanced input circuit, simplifiedschematic diagram.

4 2

d. Equalization Circuits. The equalizationcircuit provides a high frequency boost or alow frequency boost for recorded signals, dur-ing either 7½–ips or 15–ips operation. WithEQUALIZATION SWITCH S103 in the 15I.P.S. position, the output signal of tube V102Ais coupled out by capacitor C106 to the equali-zation circuit and developed across resistorsR114 and R115 in series. At the junction ofcapacitor C106 and resistor R114, the signalis fed to resistors R113, R123, and R116 inseries. Variable capacitor C107, in shunt withresistor R113, provides a virtual short circuitaround resistor R113 for the high frequencysignals. Capacitor C128 in shunt with resistorR116 provides a low-impedance path for fre-quencies above 100 cps. With EQUALIZATIONSWITCH S103 in the 7½ I.P.S. position,capacitors C108 and C135 are connected inshunt with capacitor C107 to lower the im-pedance and provide additional high frequencyboost.

e. Voltage Amplifier V102B. The inputsignal to tube V102B is taken from the junc-tion of resistors R123 and R113 and fed to thecontrol grid of the tube. The amplified outputacross plate load resistor R118 is coupled outto tube V103 control grid through capacitorC110. Plate voltage for tube V102B is takenfrom the same circuit as that for the platevoltage for tube V120A (c above) and appliedto tube V102B through plate load resistorRll8. Cathode bias is developed across resistorR117 and filtered by capacitor C109. A portionof the recorded signal is taken from the centerarm of resistor R115 and fed through contacts3 and 1 of section 2 of METER SELECTORswitch S102 and to the input of tube V105 inthe playback amplifier.

f. Recording Amplifier V103. The outputsignal of tube V102B appears across resistorR119 and is fed to the control grid of tubeV103. The amplified output across plate loadresistor R122 is coupled to connector J102through capacitor C113 and contacts 6 and 7of record relay K101 (g below). Plate voltagefor tube V103 is taken from the junction ofresistors R158 and R161 (b above) and appliedthrough plate load resistor R122. Cathode biasand negative feed-back voltage are developedacross resistor R120. Tube V103 cathode andcontrol grid are returned to an equalization

circuit consisting of coil L102, resistor R121,and capacitors C112 and C111. The equaliza-tion circuit provides additional negative feed-back for the. cathode of tube V103 and reducesthe gain of the tube at the lower frequencies.For 15-ips operation, equalization is providedby the series resonant circuit consisting of coilL102 and capacitor C112. For 7½–ips opera-tion, capacitor Cl 11 is connected across C112to lower the frequency at which the equaliza-tion action starts.

g. Record Relay K101. Record relay K101is operated by pressing RECORD switch S105.This applies 115 volts dc to the winding of thecoil and closes the relay. Contacts 12 and 9close and short RECORD switch S105 therebyholding the relay closed. High voltage from thejunction of resistor R161 and choke coil L101is applied to the plate circuit of erase-oscillatortube V107 and to RECORD INDICATOR lampI 101 through contacts 4 and 5 of relay K101.Lamp I 101 is illuminated and tube V107 oscil-lates. With relay K101 energized, the outputof recording amplifier tube V103 is connectedto connector J102 through contacts 6 and 7of relay K101. With relay K101 de-energizedthe plate circuit of the oscillator is open, andthe oscillator tube stops oscillating.

h. Erase-oscillator V107 (fig. 24). The 65–kc push-pull oscillator supplies recording biasand erase currents to the recorder and eraseheads of the soundhead assembly. The amountof erase current (fed through connector J103)is determined by the setting of capacitor C115.The level of recording bias (fed through con-nector J102) is determined by the setting ofresistor R125 and capacitor C114. The fre-quency of oscillation is determined by the tankcircuit consisting of capacitor C131 and theprimary of oscillator transformer T104. Withplate voltage applied through the primary oftransformer T104 and contacts 4 and 5 of relayK101, tube V107A conducts, and voltages ofthe resonant frequency (65 kc) of the tank aredeveloped and fed to the control grid of tubeV107B through capacitor C132. Tube V107Bconducts and voltages of the resonant fre-quency of the tank are coupled to the controlgrid of tube V107A through capacitor C133.The capacitor coupled feed-back voltage main-tains the oscillations in both tubes. At the posi-tive peaks of the feed-back voltage to the con-

4 3

Figure 24.

Figure 24. Erase-oscillator circuit, simplified schematic diagram.

4 4

Figure 25.

trol grid of tube V107A, grid current flows andcharges capacitor C133. The discharge of ca-pacitor C133 through resistor R152 developsa grid bias which blocks tube V107A. At thefollowing positive peak, the cycle is repeated.In a similar manner, grid bias for tube V107Bis developed across resistor R153. Cathode biasfor both tubes is developed across cathoderesistor R151. Because a negative feed-backvoltage is developed across resistor R151, dis-tortion of the generated signal is reduced.

i. Noise Balance Circuit (fig. 25). The noisebalance circuit cancels out the effects of re-sidual magnetic bias in the recorder headand thus lowers the noise level of the recordedinformation. A small dc voltage, impressedacross the circuit, improves the linearity of therecorded signal by suppressing the third har-monic distortion. The circuit consists of re-sistors R128 and R129 and capacitor C116 asone side, and resistors R127 and R124 as theother side. Because positive voltages of differ-ing magnitudes are applied across the recorderhead, a current will flow through the recorderhead to cancel the effects of any residual mag-netic bias. Resistor R129 is used to set the leveland polarity of current through the recorderhead.

Figure 25. Noise balance circuit, simplifiedschematic diagram.

a. General. The input signal to the playbackamplifier is taken from the reproducer headof the sound head assembly. The signal isamplified successively by playback preamplifiertube V104, voltage amplifier tube V105, andoutput amplifier tube V106. The output of tubeV106 is connected to MONITOR jack J105,to OUTPUT connector P102, and to EAR-

PHONES jack J104. The output signal maybe connected to the audio amplifier for publicaddress operation.

b. Playback Preamplifier V104. The outputof the reproducer head is fed across resistorR132 to the control grid of tube V104 throughconnector J101. The amplified output acrossplate load resistor R136 is coupled out throughcapacitor C121. Plate voltage for the tube istaken from the junction of resistor R158 andcapacitor C104C. Resistor R137 and capacitorC104B form a decoupling filter and decouplethe ac in the output of tube V104 from reach-ing the power supply circuit. Screen voltage istaken from the junction of voltage dividerresistors R137 and R135 connected across thepower supply circuit. The screen voltage isdropped by resistor R134 and filtered by ca-pacitor C118. Cathode bias is developed acrossresistor R133 and maintained at a constantlevel by capacitor C117.

c. Playback Equalization Circuit.(1)

(2)

The equalization circuit provides lowfrequency boost for playback signals.Capacitor C122 provides a low-impe-dance path for frequencies above 8 kcaround resistors R139 and R141.Capacitor C123 and resistor R140presents a high impedance to low fre-quency signals and a low impedanceto high frequencies.The output of the equalization circuitappears across PLAYBACK LEVELcontrol R142, and a portion of theplayback signal is fed to the controlgrid of tube V105 through contacts1 and 12 of section 2 of METERSELECTOR switch S102 when switchS102 is in the PLAYBACK LEVELposition. The amplified output acrossplate load resistor R146 is coupledout to tube V106 through capacitorC127. Plate voltage for tube V105 istaken from the junction of resistorR158 and capacitor C104C anddropped by resistor R146. Screen volt-age, taken from the same point, isdropped by resistor R145 and filteredby capacitor C126. Cathode biasvoltage is developed across resistorsR143 and R144 and filtered by capaci-tor C124. Negative feed-back voltage

4 5

54. Playback Circuit(fig 49 and 51)

taken from the output. of tube V106(d below) is fed through filter resistorR131 and developed across R144. Ca-pacitor C125 reduces the feed-backvoltage at the higher frequencies toimprove the frequency response of thestage.

d. Output Amplifier V106. The output signalof tube V105 is fed to the control grid of tubeV106 across grid loading resistor R147. Theamplified output across the secondary of trans-former T102 is fed to OUTPUT connector P102or EARPHONES jack J104. The amplified out-put at the primary of T102 is coupled out toMONITOR jack J105 through resistor R149and capacitor C130. Plate voltage for tubeV106 is taken from the junction of resistorR161 and capacitor C120C and applied throughthe primary of T102. Cathode bias is developedacross resistor R148 and filtered by capacitorC129. To compensate for an output load ofother than 600 ohms connected to either con-nector J104 or connector P102, LINE TERMI-NATION switch S104, when thrown - to theON position, places resistor R150 across thesecondary of transformer T102 to provide aproper substitute load.

(fig. 49) 55. Meter Ci rcui t

.a. General. Meter M101 is used to indicate

the level of playback and recorded signals, andalso to indicate the levels of the bias and erasecurrents applied to the recorder head and erasehead. Section 1 of METER SELECTOR switchS102 is used to connect the meter into theappropriate circuit; section 2 is used to closecircuits for monitoring purposes.

b. PLAYBACK LEVEL. With METERSELECTOR switch S102 in the PLAYBACKLEVEL position, meter M101 is connectedacross the secondary of transformer T102through contacts 8 and 7 and 1 and 2 of section1 of S102. Resistor R138, connected in serieswith meter M101, converts the measurementto volume units (vu). Playback circuit is com-pleted in section 2 of switch S102 and play-back can be monitored.

c. RECORD LEVEL. With METER SE-LECTOR switch S102 in the RECORD LEVELposition, the circuit to meter M101 is the sameas that used for playback except that contact3 replaces contact 2, and contact 9 replaces

contact 8. Contacts 1 and 3 of section 2 make,And recorded signals can be monitored by usingthe meter indication and/or the headset (orloudspeaker).

d. BIAS. With METER SELECTOR switchS102 in the BIAS position, and the erase-oscillator circuit operative, meter M101 is con-nected across resistor R130 in series with therecorder coil. The circuit to the meter is closedthrough contactS 1 and 4 and 7 and 10 ofsection 1 of switch S102. Section 2 of switchS102 is open. Recorded signals can be moni-tored only by using the headset or loudspeakeror both.

e. ERASE. With METER SELECTORswitch S102 in the ERASE position and theerase-oscillator circuit operative, meter M101is connected to measure the voltage drop acrossresistor R126 which is connected in series withthe erase coil, thus measuring the output oferase-oscillator tube V107. Recorded signalscan be monitored through use of the headsetor loudspeaker or both.

56. Amplifier Power Supply(fig. 49)

a. The amplifier power supply circuit supplies dc plate and screen voltages for the ampli-fier tubes and the erase-oscillator; also suppliedare ac and dc filament voltages and ac forpilot lamp I 101.

b. The 115-volt ac 60-cps line is connectedto the primary of power transformer T103through fuse F102. The stepped up voltageacross the secondary of transformer T103 isconnected to the plates of full-wave rectifiertube V108. The rectified output of tube V108is filtered by capacitor C120A, C120B, andC120C, choke L101, and resistor R161.

c. Ac filament voltage for tubes V102A,V102B, and V103 is taken from the 6.3-voltsecondary winding of power transformer T103.The same winding provides ac voltage for pilotlamp I 101,

d. Dc filament voltage for tube V101 istaken from the output of selenium rectifierCR101. Stepped down voltage from the sec-ondary of transformer T103 is connected tofull-wave rectifier CR101. The rectified outputof CR101 is filtered by dropping and surge-limiting resistor R155 and capacitor C119. Re-sistors RI 56 and R157 form a balanced load

46

to reduce hum level in tubes V101, V104, andV105.

57. Audio Amplifier Circuit(fig. 48)

a. General. The input signal to the audioamplifier is taken from the output of the play-back amplifier and fed to amplifier and phaseinverter tube V302. The tube amplifies thesignal and provides phase-inverted input sig-nals for push-pull power-amplifier tubes V303and V304. The output of the audio amplifier isconnected to the internal loudspeaker or head-set or external loudspeaker.

b. Amplifier and Phase Inverter V302 (fig.26). Input to the audio amplifier circuit aretaken from MONITOR INPUT J303 and de-veloped across MONITOR LEVEL controlR317. A portion of the signal voltage is appliedto the control grid of tube V302A. The ampli-fied output developed across plate load resistorR307 is coupled out to tube V304 by capacitorC304. Amplified signal voltage is also devel-oped across resistors R305 and R304. At thejunction of resistors R305 and R304, signalvoltage is coupled out by capacitor C302 tothe control grid of tube V302B across resistorR302. The amplified signal of V302B is devel-oped across plate load resistor R306 andcoupled out to tube V303 by capacitor C303.Feed-back voltage to reduce distortion is takenfrom the secondary of transformer T302 andfed back to the cathode of tube V302A throughfilter resistor R310 and capacitor C305. Platevoltage for tube V302A and V302B is takenfrom the junction of resistor R315 and capaci-tor C307C.

c. Power Amplifiers V303 and V304. Theinput voltage to tubes V303 and V304 is takenfrom the output of tube V302A and V302Band is impressed across resistors R309 andR308. The amplified output of tubes V303 andV304 is developed across the primary of trans-former T302. The output from the secondaryis fed to either PHONES jack J302, EXTER-NAL SPEAKER jack J301, or to internalloudspeaker LS301, through the contacts ofselector switch S301. Plate voltage for thepower-amplifier tubes is taken from the j unc-tion of resistors R314 and R315 and applied

through the primary of transformer T302.Screen voltages for the tubes are taken fromthe same junction and applied through taps onthe primary winding of transformer. T302.Common cathode bias is developed across re-sistor R312 and filtered by capacitor C306.Suppressor resistors R311 and R313, in thegrid circuits, are used to prevent parasiticoscillation.

Figure 26. Amplifier phase-inverter circuit,simplified schematic diagram.

58. Audio Amplifier Power Supply(fig. 48)

a. The power supply circuit supplies dcplate and screen voltages for the phase inverterand power-amplifier tubes. The power supplyalso furnishes ac voltages for the filaments ofthe tubes in the audio amplifier and ac for pilotlamp I 301.

b. The 115-volt ac 60-cps line is connectedto the primary of power transformer T301through fuse F301. The stepped up voltagesfrom the secondary of transformer T301 isconnected to the plates of full-wave rectifiertube V301. The rectified output of tube V301is filtered by capacitor C307A C307B, andC307C, and resistors R314 and R315.

c. Ac filament voltages for tubes V302,V308, and V304 are taken from the 6.3-voltsecondary winding of power transformer T301.The same winding provides voltage for pilotlamp I 301 through surge resistor R316.

47

CHAPTER 6

FIELD MAINTENANCE

Note. This chapter contains information for field maintenance. The amount of repair that can be performedby units having field maintenance responsibility is limited only by the tools and test equipment available and bythe skill of the repairman.

Section I. TROUBLE SHOOTING AT FIELD MAINTENANCE LEVEL

Warning: Certain points located throughoutthe chassis of the recorder-reproducer set areabove 250 volts to ground. Do not touch thesepoints while the power is on.

Warning: The failure of selenium rectifierscan result in the liberation of poisonous fumesand the deposit of poisonous selenium com-pounds. If a rectifier burns out or arcs over,the odor is strong. Provide adequate ventila-tion immediately. Avoid inhaling the fumesand do not handle the damaged rectifier untilit has cooled.

59. Trouble-shooting Proceduresa. General. The first step in servicing a

defective recorder-reproducer set is to section-alize the fault. Sectionalization means tracingthe fault to the circuit responsible for abnor-mal operation. The second step is to localizethe fault. Localization means tracing the faultto the defective part in the circuit, Some faults,such as burned+out resistors, arcing, andshorted transformers, can be located by sight,smell, or hearing. Some faults, however, mustbe localized by checking voltages and resis-tances.

b. Sectionalization and Localization. Listedbelow are tests and data that simplify the trac-ing of trouble. Follow the procedures in thesequence given. A serviceman must be careful

4 8

to cause no further damage to the equipmentwhile it is being serviced. In general, thetrouble is traced first to a circuit of the equip-ment and then to the faulty part in that circuit.The service procedure is summarized as fol-lows :

(1) Visual inspection (par. 39). Throughvisual inspection alone, the repairman may discover the trouble or locate thecircuit in which the trouble existsVisual inspection can prevent addi-tional damage to the equipmentthrough elimination of unnecessary orimproper servicing methods.

(2) Trouble-Shooting chart. The troublesymptoms listed in this chart (par.65) will aid greatly in localizingtrouble.

(3) Signal substitution. If the propersignal generators are available, it maybe preferable to use signal substitution in some cases (par. 67, 68, and69).

(4) Intermittent. The possibility of in-termittent conditions should not beoverlooked. This type of trouble maybe made to appear by tapping or jar-ring the equipment gently. Test thewiring for loose connections and movethe wires and parts with an insulatedtool, such as a fiber rod.

60. Trouble-shooting DataThe service information in this manual will

help in the rapid location of faults. Consult thefollowing trouble-shooting data:

Fig. orpar. No. Title

Fig. 27 Amplifier chassis, top view.Fig. 28 Amplifier chassis, bottom view, (capacitors

not indicated ).Fig. 29 Amplifier chassis, bottom view, (resistors

not indicated).Fig. 30 Amplifier chassis, resistor-capacitor board

(nearer to panel).Fig. 31 Amplifier chassis, resistor-capacitor board

(farther from panel).Fig. 32 Audio amplifier chassis, top view.Fig. 33 Audio amplifier chaasis bottom view.Fig. 34 Voltage and resistance chart, amplifier.Fig. 35 Voltage and resistance chart, audio ampli-

fier.Fig. 36 Recorder-reproducer, top view.Fig. 37 Recorder-reproducer, bottom view.Fig. 38 Sound head assembly.Fig. 39 Recorder-reproducer adjustment points.Fig. 43 Block diagram of test set up.Fig. 44 Playback amplifier, frequency response

curve.Fig. 45 Wording amplifier, frequency response

curve.Fig. 46 MIL-STD resistor color codes.Fig. 47 MIL-STD capacitor color codes.Par. 48 Recorder-reproducer.Par. 49 Recording or playback circuit.Par. 50 Fast rewinding circuit.Par. 51 Fast winding circuit.Par. 52 Recording input circuit.Par. 53 Recording amplifier and erase-oscillator cir-

cuit.Par. 61 Teat equipment required for trouble-

shooting.Par. 63 Checking amplifier circuits for shorts.Par. 64 Checking audio amplifier circuits for shorts.Par. 65 Trouble-shooting chart.

Dc resistances of transformers and coils.Signal substitution procedure audio ampli-

Signal substitution procedure, amplifier.

Par. 66Par. 68

61. Test Equipment Required

technical manual used with each equipmentalso is listed.

Signal Corps Common Technicalnomenclature name manual

Audio Oscillator Audio TM 11-2684ATS-382A/U oscillator

Multimeter TS-352A/U Multimeter TM 11-5527Electronic Multimeter Vtvm TM 11-5511

TS-505/USound Analyzer Distortion TM 11-5032

TS-615A/U meterFlutter Indicator

PH-593/PFQSpectrum Analyzer Test

Set TS–723/UElectron Tube Teat Set Tube tester TM 11-2661

TV-2/U

62. General Trouble-shooting PrecautionsObserve the following precautions whenever

servicing the equipment:a. Be careful servicing the equipment when

it is out of the cases; dangerous voltages arepresent.

b. If the equipment has been operating forsome time, use a cloth to remove the metal tubeshields. Use a tube puller to remove hot tubes.

c. When servicing the erase-oscillator, donot disturb the wiring and placement of parts.

d. Do not overtighten screws on mechanicalcouplings.

e. When replacing a part that was held byscrews, always replace the lock washers.

f. Careless replacement of parts often causesnew faults. Note the following points:

(1)

(2)

(3)

(4)

The test equipments required for troubleshooting the recorder-reproducer set are listed (5)below with their common usage names. The

Before a part is unsoldered, note theposition of the leads. If a part, such asa transformer or switch, has a num-ber of connections, tag each lead.Be careful not to damage other leadsby pushing or pulling them out of theway.Do not use a large soldering iron forsoldering small parts. Overheating asmall part may damage or change thevalue of the part.Do not allow drops of solder to dropon the chassis because a short circuitmay result.A carelessly soldered connection maycreate new faults.

49

Par. 69

Figure 27. Amplifier chassis, top view.

Figure 27. Amplifier chasis, top view.

50

(6)

(7)

Make wen-soldered joints because apoorly soldered joint is one of themost difficult faults to find.Replace a part exactly in the positionoccupied by the original part. Payparticular attention to proper ground-ing when replacing a part; use thesame ground as in the original wir-ing. Failure to observe these precau-tions may result in decreased outputor undesirable oscillation.

63. Chocking Amplifier Circuits for Shorts(fig. 27, 28, 29, 30, and 31)

Before servicing a unit suspected of defec-tive operation, disconnect the power cables, theinterconnecting cables, and the output cables.Also disconnect the microphone, the cable, andthe headset.

a. Measure the resistance between pins Band G of connector P103. The reading shouldbe 4 ohms. If the reading is incorrect, checkfuses F101 and F102, connector P103, and theprimary of transformer T103.

b. Measure the resistance across the 6.3-voltwinding of transformer T103. The resistanceshould be more than .1 ohm. If the reading isincorrect, remove and check tubes V102, V103,V106, and V107. Check the reading again; ifit is still incorrect, check transformer T103,

c. Measure the resistances from the platesof rectifier V108 to ground. The reading frompins 4 and 6 should be 250 ohms. If the readingis incorrect, check the high voltage secondaryof transformer T103.

d. Measure the resistance across the 12.6-volt filament of T103. The reading should bemore than .2 ohm. If the reading is incorrect,remove and check tubes V101, V104, andV105, and transformer T103. If the reading isstill incorrect, check resistors R155, R156, andR157, capacitor C119, and selenium rectifierCR101. Also check the winding of transformerT103.

e. Measure the resistance from the cathodeof V108 to ground. The reading should be 16K.If the reading is incorrect, check capacitorsC120 and C104, resistors R161, R158, R137,and R135, and relay K101.

f. Measure the resistances from the platesof tubes V101, V102, V103, V104, V105, V106,

and V107. Check the readings against thosein figure 34. If the readings are incorrect, referto the trouble-shooting chart (par. 65).

g. Measure the resistances from the screengrids of tubes V101, V104, and V105. Checkthe readings against those in figure 34. If thereadings are incorrect, refer to the trouble-shooting chart (par. 65).

h. Turn INPUT SELECTOR SWITCH S101to the MIC position.

i. Measure the resistance across terminals1 and 2 of OUTPUT connector P102. The read-ing should be 65 ohms. If the reading is in-correct, check EARPHONES jack J104 andthe secondary of transformer T102. CheckOUTPUT connector P102.

j. Measure the resistance between pins 2and 3 of INPUT connector P101. The readingshould be 25 ohms. If the reading is incorrect,check transformer T101, switch S101, and con-nector P101.

64. Ckecking Audio Amplifier Circuits forShorts

(fig. 32, 33, and 35)

Before checking the amplifier circuits, besure that all cables have been disconnected.Also disconnect the external loudspeaker andheadset.

a. Measure the resistance between the con-tacts of connector P301. The reading should be4 ohms. If the reading is incorrect, check fuseF301 and the primary of transformer T301.

b. Measure the resistance across the fila-ment winding of transformer T301. The read-ing should be less than 1 ohm. If the readingis incorrect, remove and check all tubes. Alsocheck resistor R316 and POWER lamp I 301.

c. Measure the resistance from the cathodesof tube V301 to ground. The resistance shouldbe 100K ohms minimum. If the resistance isincorrect, check capacitor C307 and resistorsR314 and R315.

d. Measure the resistance from the plates oftubes V302, V303, and V304 to ground. Checkthe readings against those in figure 35. If thereadings are incorrect, refer to the trouble-shooting chart (par, 65).

e. Measure the resistance from the screensof tubes V303 and V304, The readings shouldbe 100K ohms. If the readings are incorrect,check the primary of transformer T302.

5 1

Figure 28.

Figure 28. Amplifier chasis, bottom view (capacitors not indicated).

52

Figure 29.

Figure 29. Amplifier chasis, bottom view (resistors not indicated).

53

Figure 30.

Figure 30. Amplifier chasis, resistor-capacitor board (nearer to panel).

5 4

Figure 31.

Figure 31. Amplifier chasis, resistor-capacitor board (farther from panel).

5 5

Figure 32.

Figure 33.

Figure 32. Audio amplifier chasis, top view.

Figure 33. Audio amplifier chasis, bottom view.

5 6

65. Trouble-shooting Chart trouble has been localized, a tube check andThe following chart lists the symptoms voltage and resistance measurements should

which the repairman may observe. After the isolate the defective part.

Symptom

1. Recorder-reproducer setinoperative.

2. Capstan does not rotate withswitch S204 in either the7 ½“ or the 15” position.

3. Capstan roller does not closewith PLAY switch S206pressed.

4. Tape spills.

5. Tape breaks.

6. Tape is distorted or stretched.

7. No output signal at EAR-PHONES jack J104 withaudio amplifier disconnected.

Probable cause

1.

2.

3.

4.

5.

6.

7.

No ac power.

Defective Power CableAssembly CX-1208/U.

Defective connector P103.



Defective fuse F101 or F102.

Defective switch S203.

Defective transformer T103.


Defective capstan motor B202.

Defective capacitor C204.


Defective rectifier CR201.

Defective resistor R201.



Defective relay K201.

Defective STOP switches S201.

Brake O 201 not released,solenoid L201 defective.

Resistor R203 shorted.

Defective solenoid L203.

Brake O 203 defective.


Tape not threaded properly.

Improper tension. Gate ofsound head assembly notclosed.

Defective jack J104.


Defective power supply.

Defective playback amplifier.

Remedy

1.

2.

3.

4.

5.

6.

7.

Check power source.

Repair or replace power cables

Replace connector P103.



Replace fuse F101 or F102.

Replace switch S203 (par. 70)

Replace transformer T103(par. 70).

Replace switch S204.

Replace capstan motor B202(par. 72).

Replace capacitor C204.


Replace rectifier CR201.

Replace resistor R201.

Replace capacitor C203.


Replace relay K201(par. 70).

Replace STOP switch S201.

Replace O 201 or L201(par. 71).

Replace resistor R203.

Check, replace, or adjustL203 (par. 71)

Replace O 203 (par. 71).

Replace R202.

Refer to paragraph 13.

Close the gate.

Replace jack J104.

Replace transformer T102(par. 70).

Check power supply (items 89, and 10).

Check amplifier (items 9through, 16).

57

Symptom Probable cause Remedy

8.

9.

10.

11.

12.

13.

Same as item 7.

No voltage at pins 2 and 8 oftube V108.

Same as item 7.

Incorrect voltage at plate oftube V106 after previouschecks have been made.

Same as item 7.

Incorrect voltage at plate oftube V106.

Same as item 7.


Same as item ‘7.

Incorrect voltage at screen gridof tube V 105 after previouschecks have been made.

Same as item 7.

Incorrect voltage at control gridof tube V105.

8.

9.

10.

11.

12.

13.

Defective fuse F102.


Defective tube V108.

Capacitor C120A shorted.

Defective filament rectifierand filter circuit.

Shorted filament.

Lamp I102 shorted

Tube V106 shorted.

Defective primary of trans-former T102.

Defective filament winding oftransformer T102.

DefectiveC120C.

DefectiveR154.

Defective

capacitor C120B or

resistor R161 or

choke L101.




Capacitor C127 shorted.


Defective resistor R158, R146,R145, R143, or R144.

Defective capacitor C104C,C124, or C125.


Defective capacitor 126.


8.

9.

10.

11.

12.

13.

Replace fuse F102 (par. 41).

Check all windings oftransformer T103 (par. 66).

Replace transformer T103 ifdefective (par. 70).

Replace tube V108 (par. 40).

Replace capacitor C120A.

Check rectifier CR101.

Check resistor SR155, R156,and R157.

Check capacitor C119.

Check all filaments.

Replace defective parts.Check lamp I102.Check resistor R162.

Check tube V106(par. 40).

Check transformer T102(par. 66 and 70).

Replace defective parts.

Check capacitor C127 andresistor R147.

Check tube V105 (par. 40).

Check defective parts.

Check and replace defectiveparts.

Check and replace capacitorC121.

58

Symptom Remedy

14.

15.

16.

17.

18.

19.

20.

21.

22.

Same as item 7.

Incorrect voltage at plate oftube V104 after previouschecks have been made.

Same as item 7.parts.

Incorrect voltage at screen gridof tube V104 after previouschecks have been made.

Same as item 7.

Incorrect voltage at control gridof tube V104 after previouschecks have been made.

Poor high frequency response.

parts.

Volume does not vary when thePLAYBACK LEVEL controlis varied.

Needle of vu meter M101 doesnot vary with variation insound level.

NO output signal heard fromloudspeaker LS301 withswitch S301 turned toSPEAKER position.

No output signal heard throughexternal speaker.

No output signal heard fromheadset connected to thePHONES jack with switchS301 at the PHONES posi-tion.

Probable cause

14.

15.

16.

17.

18.

19.

20.

21.

22.


Defective resistor R136 orR133.

Defective capacitor C117 orC104B.





Defective interconnectingcable to connector J101.


Defective connector J201 orJ204.

Defective reproducer headE201.

Reproducer head misaligned.

Defective resistor R139, R141or R140.

Defective capacitor C122 orC123.

Defective PLAYBACKLEVEL control R142.

Defective METERSELECTOR swith S102.

Defective vu meter M101.


Defective amplifier.

Defective power supply.


Defective loudspeaker LS301.

Same u item 20.


Same as item 20.

Defective headset.


14.

15.

16.

17.

18.

19.

20.

21.

22.

Check tube V104 (Par. 40).


Check and replace defective

Check resistor R132.



Check and replace defective

Check and replace defectiveparts (par. 70).

Check vu meter.

Check resistor R138.


Check amplifier (items 21through 80).

Same as item 20.

Check and replace jack J301

Check headset.

Check jack J302.


59


23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

Same as items 20 through 22except that switch S301 is inthe SPEAKER PHONESposition.

Same as item 20.

No voltage at pins 2 and 8 oftube V301.

Same as item 20.Incorrect voltages at plates and

screen grids of tubes V303and V304 after previouschecks have been made.

Same as item 20.Incorrect voltages at control

grids of tubes V303 and V304after previous checks havebeen made.

Same as item 20.

Incorrect voltages at plates oftube V302 after previouschecks have been made.

Incorrect voltage at pin 2 oftube V302 after previouschecks have been made.

Incorrect voltage at pin 7 oftube V302 after previouschecks have been made.

Level of sound does not varywhen variable resistor R317is varied.

Equipment does not atop whenSTOP switch S201 is pressed.

Equipment does not rewindquickly with REWINDswitch pressed.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

Same as item 20.

Defective

Defectiveformer

DefectiveDefectiveDefectiveDefectiveDefectiveDefective

assembly

Defective

tube V301.

windings of trans-T301.resistor R314.lamp I301.capacitor C307A.fuse F301.connector P301.power cable as-CX-1208/U.

resistor R314, R315,or R312.

Defective capacitor C307B,C307C, or C306.

Defective tube V303 or V304.Defective transformer T302.

Capacitor C303 or C304shorted.

Defective resistor R308, R309,R311, or R313.


Defective resistor R306, R307,R330, R301 or R310.

Defective capacitor C301 orC305.



Defective R317.Defective J303.Defective interconnecting

cable.

Defective variable resistorR317.


Defective REWIND switchS207.

Defective relay K202.Defective relay K201.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

Same as item 20.

Replace tube V301(par. 40).


(For fuse replacement, referto paragraph 41. For check-ing and replacement oftransformer T301, refer toparagraphs 66 and 70).

Check and replace defectiveparts (par. 70).

Check capacitors C303 andC404.

Check resistors R308, R309,R311, and R313.

Replace defective tube V302(par. 40).

Check and replate defectiveparts.

Check resistors R304 and R305.

Check capacitor C302.Replace defective parts.


Check and replace variableresistor R317.

Check and replace switch S201

Check switch S207.

Check relay K202.Check relay K201.Replace defective parts

(par. 70).

60

Symptom

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

Equipment does not wind quick-ly with WIND switch pressed.

RECORD INDICATOR doesnot glow with RECORDswitch closed.

With a microphone input signaland METER SELECTORswitch S102 operated toPLAYBACK LEVEL posi-tion, recorded signal is notheard.

Same as item 35.


Same as item 35.Incorrect voltage at control grid

of tube V103.

Same as item 35.

Incorrect voltage at plate oftube V102B.

Same as item 35.Incorrect voltage at control

grid of tube V102B.

Same as item 35.

Incorrect voltage at plate oftube V102A.

Same as item 35.Incorrect voltage at control grid

of tube V102A.

Same as item 35.

Incorrect voltages at plate andscreen grid of tube V101.

Probable cause

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

Defective WINDswitch S203.Defective relay K203.

Defective interconnectingcable.

Defective connector P103.Capacitor C134 shorted.Defective relay K101.Defective RECORD INDI-

CATOR I 102.

Defective recording amplifier.Defective recorder head E202.Defective connector P202.Defective connector J102.


Defective resistor R128, R129,R127, R124, R122, R120, orR121.

Capacitor C112 or C113shorted.


Defective tube V102B.



Defective capacitor C106.Defective resistor R113, R123,

or R126.

Defective tube V102A.



Capacitor C103 shorted.Resistor R110 defective.

Defective tube V101

Defective resistor R163, R108,R109, or R107.

Defective capacitor C104A,C102, or C101.

Remedy

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

Check switch S205.Check relay K203.Replace defective parts

(par. 70).



Check recording amplifier(items 36 through 43.)

Check and replace tube V103(par. 40).


Check capacitor C110.Check resistor R119.Replace defective parts

(par. 70).

Check and replace tube V102B(par. 40).


Check capacitor C106.Check resistors R113, R123,

and R126.


Check and replace tube V102.(par. 40).


Check capacitor C103.Check resistor R110.Replace defective parts.

Check and replace tube V101.(par. 40).


61


43. Same as item 35. 43. Defective transformer T101 43. Replace defective parts(par. 66). (par. 70).

Defective INPUT SELECTORSWITCH S101.

Defective INPUT connector.P101.

Defective microphone or micro-phone cable.

44. Equipment does not record sig- 44. Defective resistor R159, R160, 44. Check switch S101.nal to bridging circuit input. R101, R102, R103, or R104. Replace if defective; refer to

paragraph 70.Defective switch S101. Replace defective resistors.

45. Equipment does not record sig- 45. Defective resistor R105, or 45. Check switch S101.nal to 600-ohm balanced line R106. Replace if defective; refer toinput. paragraph 70.

Defective switch S101. Replace defective parts.

46. Equipment does not record sig- 46. Defective switch S101. 46. Check and replace switch S101nal to 600-ohm unbalanced (par. 70).line input.

47. Level of sound does not vary 47. Defective control R110. 47. Check and replace control R110.when RECORD LEVEL con-trol is turned.

48. Poor frequency response. 48. Defective resistors R113, R114, 48. Check and replace defectiveR115, R116, or R123. parts.

Defective EQUALIZATIONswitch S 103.

Defective capacitor C107, C108,C121, C111, or C112.

Defective coil L102.

49. Distortion present during mon- 49. Erase-oscillator V107 49. Replace tube V107 (par. 40)itoring of recording on a pre- defective. (ace items 50 through 52).viously recorded tape. Defective erase head E203. Replace defective parts.

Defective connector P203.Defective interconnecting

cable.Defective connector J103.

50. Same as item 49. 50. Defective transformer T104. 50. Check and replace defectiveIncorrect voltages at plates of Defective capacitor C131. parts (par. 70).

tube V107.

51. Same as item 49. 51. Defective resistor R151, R152, 51. Replace defective parts.Incorrect voltages at control R153, or R162.

grids of tube V107. Defective capacitor C132, orC133.

62. Same as item 49. 52. Capacitor C115 defective. 52. Replace defective parts.Defective connector J103.Defective resistor R126.

53. Excessive recording noise. 53. Noise balance circuit mia- 53. Refer to paragraph 85.aligned.

62

66. Dc Resistances of Transformers and CoilsThe dc resistances of the transformers and

coils in the recorder-reproducer set are listed

b.wave

An oscilloscope is used to observe theform, a vacuum-tube voltmeter to meas-

ure the voltage, or, under certain conditions, aloudspeaker or headset may be used to listen tothe signal.

Caution: Do not remove the shield cans orother shields for tubes and parts unless thetrouble has been traced to that particular part.Do not push the wiring out of place. Pushingthe wiring back and forth may cause brokenconnections, change the frequency of the erase-oscillator, or alter the characteristics of acircuit.

c. When connecting a signal generator tothe control grid of a tube, connect a capacitor(.05 microfarad) in series with the output(high side) of the signal generator.

d. After trouble is traced to a circuit, dis-connect the test equipment and make voltageand resistance measurements to localize thedefective part (fig. 30, 31, 34, and 35).

68. Signal Substitution Procedure, AudioAmplifier

(fig. 48)

a. Set the signal generator (Audio Oscil-lator TS-382A/U or equivalent) to 1,000 cps.

b. Connect and operate the audio amplifier.c. Turn the function switch to the SPEAK-

ER position.d. Connect the output of the signal gene-

rator through a suitable capacitor to the plateof tube V304. A signal should be heard fromthe loudspeaker (Do not overload the audioamplifier.) Connect the output of the signalgenerator to the control grid of tube V304.Signal volume should increase. If not, refer tothe trouble-shooting chart (par. 65).

e. Repeat the procedure given in d abovefor tube V303 and for phase inverter V302.Reduce the level of the input signal for eachsuccessive stage.

69. Signal Substitution Procedure, Amplifier(fig. 49)

a. Set the signal generator (Audio Oscil-lator TS-382A/U or equivalent) to 1,000 cps.

b. Connect and operate the amplifier.c. Turn METER SELECTOR switch S102

to the PLAYBACK LEVEL position.

63

below.

Transformer Leads | Ohmsor coil

K101— —L101- — —L102- —T101

T102

1 and 10 4,500

Across coil 250

Across coil 90

Yellow to yellowGreen to black

Red to blueBrown to brown

253,100

1,60065

T103 Black to blackGreen to green-yellowGreen-yellow to greenRed to red-yellowRed-yellow to redYellow to yellowBrown to violetViolet to brown

4Less than 1Less than 1

250250

Less than 1Leas than 1Less than 1

101017

T104 Blue to redRed to blueYellow to black

K201

K202

1 and 10 4,500

1 and 10 4,500

K203 1 and 10 4,500

Across terminals 2,400L201

L202 Across terminals 1,200

L203 Across terminals 2,400

4Less than 1

130130

Less than 1

Black to blackT301Yellow to yellowRed to red-yellowRed-yellow to redGreen to green-yellowGreen-yellow to green Less than 1

T302 Blue to blue-white I 85Blue-white to redRed to green-whiteGreen-white to greenYellow to black

353585

Leas than 1

67. Signal Substitution

General notes on signal substitution andsignal tracing are as follows:

a. An audio signal generator is required togenerate the signal of proper voltage and fre-quency that is to be traced through the equip-ment.

Figure 34.

Figure 35. Voltage and resistance chart, audio amplifier.

6 4

Figure 34.

Figure 35. Voltage and resistance chart, audio amplifier.

6 5

d. Connect the headset to EARPHONESjack J104.

e. Connect the output of the signal generatorthrough a suitable capacitor to the plate oftube V106. A signal should be heard in theheadset. (Do not overload the amplifier.) Con-nect the output of the signal generator to thecontrol grid of tube V106. Signal volume shouldincrease. If not, refer to the trouble-shootingchart (par. 65).

f. Repeat the procedure given in e above

for tubes V105 and V104. Reduce the level ofthe input signal for each successive stage.

g. Turn the METER SELECTOR switch to the RECORD LEVEL position.

h. Repeat the procedure given in e above fortubes V102A and V101.

i. Remove the headset from EARPHONESjack J104 and connect it to contact 6 of relayK101 and ground;

j. Repeat the procedure given in e above fortubes V103 and V102B.

Section II. REPAIRS

70. Replacement of Partsa. Most of the components of the recorder-

reproducer set are readily accessible and canbe replaced easily using common hand tools.

b. If switch S101, S102, or S301 requiresreplacement, carefully mark the wires con-nected to the switch wafers with tags to avoidwiring errors.

c. If relay K101, K201, K202, or K203 (fig.27 and 37) requires replacement, carefullymark the wires connected to the relays withtags to avoid wiring errors.

d. If transformer T101, T102, T108, T104,T301, or T302 requires replacement, carefullymark the wires with tags to avoid wiringerrors.

71. Disassembly Procedure, Recorder-reproducer

(fig. 36, 37, and 41)

Remove the recorder-reproducer from thecase as follows:

a. Remove the editing knobs from both reelsby rotating the knobs counterclockwise.

b. Be sure the tape is wound on one reel.Remove the tape reels.

c. Remove the hub adapters.d. Remove the eight No. 10 screws that hold

the recorder-reproducer to the case.e. Lift the unit out of the case.f. Disconnect the interconnecting power

cable.g. Disconnect connector P201 from connec-

tor J101, disconnect connector P202 from con-nector J102, and disconnect connector P203from connector J203.

72. Replacement of Supply and Take-upMotors

To remove either of these motors, disconnectall leads, remove the recorder-reproducer (par.71), and proceed as follows:

a. Remove the three No. 4 flat head screwsthat hold the spindle. Remove the spindle.

b. Remove and tag the electrical connectionsfrom the motor to terminal board E204 orE206 (fig. 37).

c. Remove the four No. 10 binding head screws that hold the motor to the front panelof the recorder-reproducer. Be sure to hold themotor and, at the same time, loosen the screwsto prevent dropping the motor. Remove themotor.

d. Loosen the four No. 6 binding headscrews that hold the brake assembly to themotor. Remove the brake assembly.

e. Loosen the two No. 8 Allen head screwsthat hold the brake pulley to the motor shaft.

f. To install the new motor, reverse theprocedure outlined in a through e above.

73. Replacement of Capstan MotorTo remove the capstan motor (fig. 37), dis-

connect all leads, remove the recorder-repro-ducer (par. 71), and proceed as follows:

a. Remove and tag the electrical connectionsfrom the motor to terminal board E205.

b. Loosen the four No. 10 nuts that holdthe motor to the recorder-reproducer assembly.Be sure to support the motor when looseningthe nuts. Remove the motor.

c. To install the new motor, reverse theprocedure outlined in a and b above.

6 6

Figure 36.

Figure 37.

Figure 36. Recorder-reproducer, top view.

Figure 37. Recorder-reproducer, bottom view.

6 7

Figure 38.

Figure 38. Sound head assembly.

6 8

Figure 39.

Figure 39. Recorder-reproducer, adjustment points.

69

Figure 40.

(fig. 38)74. Replacement of Sound Head Assembly screws and the two No. 6 binding head screws

that hold the sound head assembly.

a. Remove the two No. 6 binding head c. Lift off the sound head assembly.screws that hold the cover of the sound head d. To install the sound head assembly, re-assembly. Remove the cover. verse the procedure outlined in a through c

b. Remove the two No. 6 fillister head above.

Section III. MECHANICAL ADJUSTMENTS

75. GeneralIf a motor is replaced, the solenoid and the

brake belt tensions of both the supply reelmotor and the take-up reel motor must be ad-justed. Follow the directions given in para-graphs 76 through 78 to make the adjustments.

76. Solenoid Throw Adjustment(fig. 39)

To adjust the throw of the solenoid, proceedas follows:

a. Push the plunger into the solenoid to thelimit of travel.

b. Release the solenoid plunger. The plungershould throw between 1/8 inch and 3/16 inchwhen released.

c. If the throw is incorrect, adjust the sole-noid by moving the two screws in the slots toobtain correct throw. Tighten the screws.

77. Brake Belt Tension Adjustments (fig. 39)

a. General. The brake belts of the take-upreel and supply-reel motors require adjustmentif the recording tape Continually breaks orspills, or if the adjustments of the brakes areunequal. Proper braking action is such that thebrakes will stop the motor in about 4 secondswith a full 10½-inch reel of tape on the turn-table, or if a l-pound pull is required to movethe solenoid plunger.

b. Adjustments. To adjust the brake belttension, proceed as follows:

(1) Clean the surface of the brake pulleywith Cleaning Compound (par. 31).

(2) Adjust the two No. 8-32 nuts on thespade bolt that hold the brake tensionspring until proper braking action isobtained (a above).

c. Additional Adjustments. When operatingthe equipment with a 7-inch reel, move the tapeof resistor R202 (fig. 37) to the 150-ohmposition.

70

78. Pressure Roller Adjustment

To adjust the pressure roller against the tapecapstan drive, proceed as follows:

a. Press the pinch roller against tape cap-stan shaft.

b. Loosen the two No. 6-32 nuts on thesolenoid guide bracket (fig. 39).

c. Loosen, but do not remove, the two setscrews on the lower end of the actuator arm(fig. 39).

d. Adjust the actuator arm until the sole-noid plunger is approximately 1/16-inch awayfrom the completely closed position.

Note. The pinch roller must be held in aclosed position.

e. Tighten the set screws in the actuatorarm.

f. Adjust the solenoid guide bracket to per-mit the pinch roller to open 1/8-inch from thecapstan shaft.

g. Tighten the No. 6–32 nuts.h. Adjust the large nut at the end of the

solenoid plunger until the tape exerts a l-poundpull when the solenoid is energized.

Figure 40. Audio amplifier, front view.

Figure 41.

Figure 42.

Figure 41. Amplifier carrying case, front view.

Section IV. FINAL TESTING

79. Inspection After Repair

Before testing the equipment, a mechanicaland electrical inspection should be performed.

a. Mechanical Inspection.(1) Check all soldered connections.

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

See that all tubes are seated firmly intheir respective sockets.See that all resistor and capacitorleads are clear of adjacent terminalsor lugs.Look for drops of solder between ter-minals on rotary switches and else-where on the chassis.Check for frayed wires and for sharppoints of solder penetrating wire in-sulation.See that all mounting screws aretight.See that all cable clamps fit snuglyover the cables.Examine the core of loudspeakerLS301. Check the voice-coil connec-tions.See that the set screws on all panelcontrol knobs make firm contact withtheir respective control shafts.Check the action of all controls forpositive response to knob rotation.See that the pilot lamps and theRECORD INDICATOR lamp are se-cure in their sockets.

71

Figure 42. Recorder-reproducer carrying case,rear view, access door open.

Figure 43.

Figure 43. Block diagram of test setup.

7 2

b. Electrical Inspection. Refer to the equip-ment performance check list (par. 43), Checkthe equipment operation as a recorder, as areproducer, and as a public address set.

80. Audio Amplifier Check

To check the operation of the audio ampli-fier, proceed as follows:

a. Turn function switch S301 to theSPEAKER position.

b. Connect a dummy load of 8 ohms resist-ance rated at 20 watts to the EXTERNAL

. SPEAKER jack with a suitable connector,c. Connect the audio amplifier to a 115-volt,

60-CPS line and allow at least 5 minutes forwarm up.

d. Connect a vtvm across the dummy load.e. Connect a distortion meter across the

dummy load.f. Connect an audio oscillator across con-

tacts 1 and 3 of the MONITOR INPUT con-nector.

g. Adjust the output of the audio oscillatorto 3 volts at 400 cps.

h. Adjust the MONITOR LEVEL controluntil the vtvm indicates 8 volts ac.

i. The distortion meter should indicate lessthan 1 per cent distortion.

j. Repeat the instructions given in h and iabove for frequencies of 400, 1,000, 5,000, and10,000 cps.

81. Audio Amplifier GainTo check the over-all gain of the audio

amplifier, proceed as follows:a. Connect the equipment as indicated in

paragraph 80.b. Connect a dummy load as indicated in

paragraph 80.c. Turn the MONITOR LEVEL control to

a setting of 10..d. Adjust the output of the audio oscillator

to 1.5 Volta.e. The needle of the vtvm should indicate

8 volts ac.

82. Frequency Response, Playback AmplifierCircuit of Amplifier

(fig. 44)

a. Connect a voltage divider (3.3K and 10ohms) across the output of an audio oscillatorConnect the playback input jack J101 of the

(fig. 43)

amplifier to the 10-ohm resistor of the voltagedivider.

b. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position.

c. Move the LINE TERMINATION switchto the ON position.

d. Connect a vtvm across pins 2 and 3 of theOUTPUT connector.

e. Connect the equipment to a 115-v, ac60-cps power source and allow at least 5 min-utes for warm up.

f. Adjust the output of the audio oscillatorto 1 volt at 50 cps for all measurements.

g. Adjust the PLAYBACK LEVEL controluntil the needle of the vtvm indicates 4 volts.

h. Adjust variable resistor R140 (fig. 27)to obtain the frequency response curve indi-cated in figure 44. Readings may vary ±2 db.Use the chart below.

Frequency Output (volts)

50 cps1 kc5 kc10 kc

4. 3

.11

.12

83. Amplifier Gain, Playback Amplifier Cir-cuit of Amplifier

To check the over-all gain of the playbackamplifier, proceed as follows:

a. Connect the equipment as indicated inparagraph 82.

b. Operate the LINE TERMINATIONswitch to the OFF position.

c. Operate the equipment for playback.d. Connect an audio oscillator to the voltage

divider (fig. 44). Adjust the audio oscillatorfor a 1-volt output at 1 kc.

e. Operate the PLAYBACK LEVEL controlto a setting of 10.

f. Operate the METER SELECTOR switchto the PLAYBACK LEVEL position. Vu meterM101 should indicate -6 vu ±2 vu.

84. Frequency Response, Recording Ampli-fier Circuit of Amplifier

(fig. 45)

The frequency response of the recordingamplifier should be checked for both 15-ipsand 7 ½-ips operation. Check the 15-ips opera-tion as follows:

a. Connect a 1K resistor from the junctionof capacitor C113 (fig. 27) and resistor R127

73

Figure 44. Playback amplifier frequency response curve.

to ground. Connect the vtvm across the 1Kresistor.

b. Connect the equipment to a power source,and operate the equipment,

c. Turn the EQUALIZATION switch to the15 I.P.S. position.

d. Turn the INPUT SELECTOR SWITCHto the BRIDGE position.

e. Connect an audio oscillator to pins 2 and3 of the INPUT connector. Set the audio oscil-lator to deliver a .5-volt output at 1 kc.

f. Adjust the RECORD LEVEL controluntil the needle of the vtvm indicates a .78volt.

g. Set the audio oscillator to deliver a .5-voltoutput at 10 kc.

h. Adjust capacitor C107 (fig, 27) until theneedle of the vtvm indicates the level shownon the curve of figure 45.

i. Similarly, check the response at 5 kc.j. Check the frequency response at 7 ½-ips

operation in the same manner indicated for15 ips (a through i above), except for thefollowing:

74

(1) Turn the EQUALIZATION switch tothe 7½ I.P.S. position.

(2) Check the response at 400 cps, 1 kc,3 kc, 5 kc, and 7 kc,

(3) Adjust capacitor C108 (fig. 27) in-stead of C107.

85. Amplifier Gain, Recording Amplifier Cir-cuit of Amplifier

To check the over-all gain of the recordingamplifier, proceed as follows:

a. Connect and operate the equipment asindicated in paragraph 83.

.

b. Turn the EQUALIZATION switch to the15 I.P.S. position.

c. Turn the INPUT SELECTOR SWITCHto the BRIDGE position.

d. Connect an audio oscillator to pins 2 and3 of the INPUT connector. Set the audio oscil-lator for .1-volt output at 1 kc.

e. Turn the RECORD LEVEL control to asetting of 10.

f. The needle of the vtvm should indicate.28 volt ±.05 volt.

86. Recording Bias Adjustment

To adjust the bias level to the recorder head,proceed as follows:

a. Remove the cover of the sound headassembly (fig. 38).

b. Demagnetize the heads in the sound headassembly with a standard demagnetizer. Bringthe tip of the demagnetizer near the core ofthe head and run the demagnetizer up anddown. Slowly remove the demagnetizer fromthe head.

c. Adjust the controls of the equipment forrecording at 15 ips.

d. Install and thread the tape.e. Connect an audio oscillator to pins 2 and

3 of the INPUT connector. Set the oscillatorto deliver an output of .5 volt at 400 cps.

f. Turn the INPUT SELECTOR SWITCHto the BRIDGE position.

g. Connect the equipment to a power source,turn on the equipment, and allow 5 minutes forwarm up.

h. Adjust the RECORD LEVEL control toa setting of 2.

i. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position.

j. Adjust the PLAYBACK LEVEL controlto a setting of 8.

k. Press the PLAY and RECORD switches.1. Turn variable resistor R125 (fig. 27) to

the extreme counterclockwise position; thenturn the control clockwise until the needleof meter M101 indicates maximum. Continueturning the control clockwise until the needleof the meter indicates 1 vu less than maximum.Note the reading of the meter.

m. Turn the METER SELECTOR switch tothe BIAS position. Adjust variable resistorR130 (fig. 27) until the needle of the meterindicates O vu.

n. Repeat the instructions given in l and mabove.

o. Turn the METER SELECTOR switch tothe RECORD LEVEL position. Adjust variableresistor R115 (fig. 27) to obtain readingsidentical with those given in 1 above.

87. Noise Balance AdjustmentTo adjust the noise balance, first adjust the

bias as indicated in paragraph 86, then proceedas follows:

a. Connect Sound Analyzer TS-615A/U(distortion meter) to the output of the ampli-fier. Adjust the distortion meter for 800-cpsoutput.

b. Connect an audio oscillator to the INPUTconnector. Adjust the audio oscillator for 400–cps output.

c. Install and thread a tape that has beenerased.

d. Operate the RECORD LEVEL controluntil the needle of vu meter M101 indicateso vu.

e. Operate the PLAYBACK LEVEL controlto a setting of 8.

f. Press the PLAY and the RECORDswitches.

g. Slowly turn variable resistor R129 (fig.27) to the extreme counterclockwise position.Note the setting for minimum second harmonicdistortion. Slowly turn variable resistor R129to the extreme clockwise position. Note thesetting for minimum second harmonic distor-tion. Repeat this procedure until the best set-ting for minimum second harmonic distortionis found.

h. After adjusting the noise balance, re-check the bias level adjustment (par. 86).

i. If a distortion meter is not available,noise balance can be obtained using a suitableheadset. First adjust the bias (par. 86), thenproceed as follows:

(1)

(2)

(3)

Connect the headset to the output ofthe amplifier.Operate the equipment as indicated inc through f above.Listen to the level of the high fre-quency noise through the headset. Ad-just the setting of variable resistorR129 (fig. 27) until the best settingfor minimum noise level is found.

88. Erase Current Adjustment

To adjust the level of erase current, proceedas f ollows :

a. Connect and operate the equipment as arecorder (par. 14).

b. Turn the METER SELECTOR switch tothe ERASE position.

c. Depress the PLAY and the RECORDswitches.

d. Adjust capacitor C115 (fig. 27) until theneedle of vu meter M101 indicates 0 vu.

7 5

89. Reproducer Head Alignment(fig. 38)

Alignment of the reproducer head consistsof adjusting the position of the head in azimuthto assure proper frequency response, low noise,high output, and low distortion. Normally, thehead will not require alignment, except if thehead has been removed, or if the entire soundhead assembly is replaced. To align the re-producer head, proceed as follows:

a. Remove the cover of the sound headassembly.

b. Demagnetize the head, using a standarddemagnetizer. Bring the tip of the demagne-tizer near the core of the head and then runthe demagnetizer up and down. Slowly removethe demagnetizer from the head.

c. Connect the equipment for playback op-eration at 15 ips (par. 10).

d. Obtain a standard tape and thread thetape.

e. Adjust the PLAYBACK LEVEL controlto a setting of 10.

f. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position.

g. Turn on the equipment and allow 5 min-utes for warm up.

h. Operate the equipment for playback (par.18) with a 10-kc signal from the standard tape.

i. Turn the tension screw that holds the re-producer head until the needle of vu meterM101 indicates a maximum reading.

90. Recorder Head Alignment(fig. 38)

To align the recorder head, first align thereproducer head (par. 89), then proceed asfollows :

a. Connect the equipment for recording at15 ips (par. 10).

b. Install and thread a blank tape.c. Connect an audio oscillator to pins 2 and

3 of the INPUT connector.d. Turn the INPUT SELECTOR SWITCH

to the BRIDGE position.e. Turn on the equipment and allow 5 min-

utes for warm up.f. Adjust the audio oscillator to deliver

1-volt output at 10 kc.g. Adjust the RECORD LEVEL control

until the needle of meter M101 indicates –5 vu.h. Connect a vtvm across pins 2 and 3 of

the OUTPUT connector.

i. Turn the METER SELECTCOR switch tothe PLAYBACK LEVEL position.

j. Press the PLAY and the RECORD switches.

k. Adjust the tension screw that holds therecorder head until the needle of the externalvtvm indicates a maximum reading.

91. Recording Amplifier and PlaybackAmplifier, Frequency Response

The frequency response of the recordingamplifier and playback amplifier should be checked for both 15-ips and 7½-ips operationafter alignment of the sound head (pars. 89and 90). First check the 15-ips operation asfollows :

a. Connect the equipment to a power source.b. Turn the EQUALIZATION switch to the

15 I.P.S. position.c. Move the 7½”–15” switch to the 15”

position.d. Turn the METER SELECTOR switch to

the RECORD LEVEL position.e. Turn the INPUT SELECTOR SWITCH

to the BRIDGE position and turn the RECORDLEVEL control to a setting of 8.

f. Connect an audio oscillator to pins 2 and 3 of the INPUT connector. Set the audiooscillator to deliver a .5-volt output at 1 kc.

g. Turn the equipment on and push thePLAY and the RECORD switches.

h. Adjust the RECORD LEVEL controluntil the needle of meter M101 indicates–l0 vu.

i. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position. The needleof meter M101 should indicate –10 vu.

j. Set the audio oscillator to deliver a .5-voltoutput at 10 kc.

k. Adjust capacitor C107 (fig. 27) until the needle of meter M101 indicates –10 vu ±2 vu.

1. Repeat the instruction given in g, h, andi above. If the reading is not –10 vu ±2 vu,reset capacitor C107, then repeat the instruc-tions given in j and k above. Record the meas-urements.

m. Set the audio oscillator to deliver a 1-voltoutput at 50 cps; the reading should be –10 vu±2 vu.

n. Check the response at 100, 400, and 500cps. Record the measurements.

76

o. If the readings are incorrect, recheck thebias adjustment (par. 86), head alignment(par. 89, and 90), tape magnetization (par.88), and settings of variable resistors R140and R125 (fig. 27).

p. Check the frequency response at 7½-ipsoperation in the same manner as indicated for15 ips (a through o above), except for thefollowing:

(1) Set the EQUALIZATION switch tothe 7½ I.P.S. position.

(2) Set the 7%”-15” switch to the 7”position.

(3) Check the equipment at 400 cps, 1 kc,3 kc, 5 kc, and 7 kc.

(4) Adjust capacitor C108 instead of ca-pacitor C107.

n. Total harmonic distortion as read on theTS-615A/U should be less than 3 per cent,

o. Repeat the instructions given in g throughn above except for the following:

(1) Operate the EQUALIZATION switchto the 7 ½ I.P.S. position.

(2) Move the 7½’’-l5” switch to 7½position.

p. If total harmonic distortion exceeds 3per cent, proceed as follows:

(1) Demagnetize the sound heads.(2) Check the bias level adjustment

(par. 86).(3) Check the noise balance circuit ad-

justment (par. 87).(4) Check the amplifier (par. 82 through

85).

92. Distortion Measurements, AmplifierTotal harmonic distortion of the amplifier

should be checked for both 15-ips and 7½-ipsoperation. First check the 15-ips operation asfollows:

a. Connect the equipment to a power source.b. Turn the EQUALIZATION switch to the

15 I.P.S. position.c. Move the 7½’’-16” switch to the 15”

position.d. Turn the INPUT SELECTOR SWITCH

to the BRIDGE position.e. Turn the METER SELECTOR switch to

the RECORD LEVEL position.f. Set the PLAYBACK LEVEL control to

8, approximately.g. Connect an audio oscillator to the INPUT

connector. Set the audio oscillator to deliver al-volt output at 400 cps.

h. Turn the equipment on and press thePLAY and the RECORD switches.

i. Adjust the RECORD LEVEL controluntil the needle of vu meter M101 indicateso vu.

j. Connect Sound Analyzer TS–615A/U tothe EARPHONES jack.

k. If a 600-ohm output of the amplifier isrequired, move the LINE TERMINATIONswitch to the ON position.

l. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position.

m. Adjust the PLAYBACK LEVEL controluntil meter M101 indicates 0 vu.

93. Flutter and Wow MeasurementsFlutter and wow of the recorder-reproducer

should be checked for both 15-ips and 7½-ipsoperation. The procedure for checking flutterand wow is the same for both speeds, exceptfor control settings. Proceed as follows:

a. Connect the equipment to a suitablepower source.

b. Connect the audio amplifier to the am-plifier.

c. Turn the EQUALIZATION switch to the15 I.P.S. position.

d. Move the 7½’’- 15” switch to the 15”position.

e. Turn the INPUT SELECTOR SWITCHto the BRIDGE position.

f. Turn the METER SELECTOR switch tothe RECORD LEVEL position.

g. Set the PLAYBACK LEVEL control to8, approximately.

h. Connect an audio oscillator to the INPUTconnector; set the audio oscillator to deliver al-volt output at 3,000 cps.

i. Turn the equipment on and press thePLAY and the RECORD switches.

j. Adjust the RECORD LEVEL control untilthe needle of meter M101 indicates O vu.

k. Connect Flutter Indicator PH-593/PFQto the PHONES jack and turn on the PH–593/PFQ. Operate the PH-593/PFQ in accord-ance with instructions furnished with theequipment.

l. Turn the METER SELECTOR switch tothe PLAYBACK LEVEL position.

7 7

Figure 45.

Figure 45. Recording amplifier, frequency response curve.

7 8

m. Adjust the PLAYBACK LEVEL controluntil meter M101 indicates 0 vu.

n. Total flutter and wow should be less than .2per cent.

o. Make measurement for 7½-ips operationwith the EQUALIZATION SWITCH set to the7½” position. Total flutter and wow should beless than .25 per cent.

94. Signal-to-noise Ratio

To measure the signal-to-noise ratio, proceedas follows:

a. Connect the equipment to a suitable powersource.

b. Turn the INPUT SELECTOR SWITCH tothe BRIDGE position.

c. Turn the EQUALIZATION switch to the7½ I.P.S. position.

d. Move the 7½-15” switch to 7 ½” position.e. Connect a vuvm and a distortion meter

across the OUTPUT connector.f. Turn the METER SELECTOR switch to the

PLAYBACK LEVEL position.g. Connect an audio oscillator to pins 2 and 3

of the INPUT connector Adjust the audio oscil-lator to deliver a 5-volt output at 400 cps.

Place a tape on the recorder-reproducer andthread the tape.

h. Move the ON-OFF switch to the ONposition.

i. Press the PLAY and the RECORDswitches.

j. Turn the RECORD LEVEL control untilthe distortion meter indicates 3 per cent thirdharmonic distortion. Simultaneously, turn thePLAYBACK LEVEL control until meter M101indicates O vu. Adjust both controls until bothconditions are obtained.

k. Record for 2 minutes.l. Press the STOP switch,m. Press the REWIND switch to allow

playback of the recorded signal (k above),then press the STOP switch.

n. Press the PLAY switch.o. Turn the PLAYBACK LEVEL control to

maintain a reading of O vu on meter M101.Record the output indicated on the vtvm.

p. When the signal disappears (extremelylow reading on vtvm), record the reading ofthe vtvm.

q. The signal-to-noise ratio is determined byratio of the values in o and p above. Ratioshould be 50 db minimum.

7 9

Figure 46.

Figure 46. MIL-STD resistor color codes.

8 0

Figure 47.

Figure 47. MIL-STD capacitor color codes.

8 1

CHAPTER 7

SHIPMENT AND LIMITED STORAGE

TO PREVENT ENEMY

AND DEMOLITION

USE

95. Removing Equipment from Servicea. Disconnect the power cable from the

power source.b. Disconnect the microphone and the head-

set (and external speaker, if used).c. Disconnect the interconnecting power

cable and output cable.

96. Materials Required for Repacking

a. The following chart lists the materialsrequired for repacking the recorder-reproducerset after the equipment has been removed fromservice.

Material

Waterproof barrier material

Corrugated fiberboard, single-faced,flexible

Gummed tape

Pressure+sensitive tape

Strapping steel, flat

Wooden shipping box

Quantity

50 sq ft

55 sq ft

40 ft

36 ft

33 ft

2 ea.

b. Fabricate the two wooden shipping boxesto the size indicated in the chart below.

1. Recorder-repro-ducer carrying

Boardfeet

27 3/8

28

97. Repackinga. Package each technical manual within a

close-fitting bag fabricated of waterproof bar-rier material. Seal the seams with waterresistant, pressure-sensitive tape.

b. Package each spare tube in flexiblesingle-faced, corrugated fiberboard and securthe wrap with gummed paper tape. Consolidatethe packaged tubes within a wrap of flexiblesingle-f aced corrugated fiberboard, and securethe consolidated wrap with gummed papertape.

c. Place each reel in a metal container andseal the container with pressure-sensitive tape;package each spare part and each accessoryitem in the same manner indicated in b above.

d. Stow all items within the compartmentsof the audio amplifier carrying case. Close thecase cover and secure the fastenings.

e. Close the covers of the recorder-repro-ducer carrying case and secure the fastenings.

f. Cushion each carrying case on all sur-faces with pads fabricated of flexible, single-faced, corrugated fiberboard. Secure thecushioning with gummed paper tape.

g. Place a suitable waterproof case linerwithin each wooden case.

h. Place each cushioned carrying case with-in the suitable wooden case. Seal the case linerwith waterproof tape.

i. Close and nail the wooden case.j. For intertheater shipments, use steel

strapping to secure the sides, top, and bottomof the cases.

k. Mark cases in accordance with the re-quirements of SR-55-720-1, Section II.

82

98. Methods of DestructionNote. The demolition procedures outlined in

a through g below will be used to prevent theenemy from using or salvaging this equipment.Demolition of the equipment will be accom-plished only upon order of the commander.

a. Smash. Smash the controls, tubes, capaci-tors, transformers, switches, microphone, loud-speakers, headsets, meters, and motors; usesledges, axes, handaxes, pickaxes, hammers,crowbars, or other heavy tools.

b. Cut. Cut the power cables, the headset

cord, the microphone cord, and all intercon-necting cables; use axes, handaxes, or ma-chetes.

c. Burn. Burn all cords, carrying cases, andtechnical manuals; use gasoline, kerosene, oil,flame throwers, or incendiary grenades.

d. Bend. Bend all panels.e. Explosives. Use firearms, grenades, or

TNT.f. Disposal. Bury or scatter the destroyed

parts in slit trenches, fox holes, or throw theminto streams.

83

I N D E X

AAdjustments:

Bias level . . . . . . . . . . . . . . . . . . . .Brake belt tension . . . . . . . . . . . .Erase current . . . . . . . . . . . . . . . .Noise balance circuit . . . . . . . . . .Pressure roller . . . . . . . . . . . . . . . Solenoid limiting am. . . . . . . . . .Solenoid throw . . . . . . . . . . . . . . . Take-up reel tension . . . . . . . . . . .

Alignment:General . . . . . . . . . . . . . . . . . . . Recorder head . . . . . . . . . . . . . . . Reproducer head . . . . . . . . . . . . Teat equipment required . . . . . . . .

Amplifier:Checking . . . . . . . . . . . . . . . . . . . .Circuit analysis:

Recording . . . . . . . . . . . . . . . . . .Reproducing . . . . . . . . . . . . . . . .

Connectors . . . . . . . . . . . . . . . . . . Controls . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . .Final test . . . . . . . . . . . . . . . . . . .

Amplifier, audio:Checking . . . . . . . . . . . . . . . . . . . . Circuit analysis . . . . . . . . . . . . .Connectors . . . . . . . . . . . . . . . . . . . .Controls . . . . . . . . . . . . . . . . . . . . . . .Description . . . . . . . . . . . . . . . . . . Final teat . . . . . . . . . . . . . . . . . . . .

Arctic operation . . . . . . . . . . . . . . .

BBias adjustment . . . . . . . . . . . . . . . .Block diagrams:

Playback . . . . . . . . . . . . . . . . . . . . . Audio amplifier . . . . . . . . . . . . . . .Recording . . . . . . . . . . . . . . . . . . . .

Brakes:Adjustment . . . . . . . . . . . . . . . . . . Operation . . . . . . . . . . . . . . . . . . .

CCapstan motor:

Lubrication . . . . . . . . . . . . . . . . . . Operation . . . . . . . . . . . . . . . . . . . . . Replacement . . . . . . . . . . . . . . . . .

Cables . . . . . . . . . . . . . . . . . . . . . . . . .Case, amplifier:

Paragraph Page

8677888778767677

79908961

63

535429 a28 a6c

91

645729b28b6f

80, 8125

86

465745

7749

3549736

7570757570707070

71767649

51

424524233

76

514724233

7321

75

384738

7040

2940663

Paragragh PageDescription . . . . . . . . . . . . . . . . . 6eDimension . . . . . . . . . . . . . . . . . . . 5

Case, recorder-reproducer:Description . . . . . . . . . . . . . . . . . . 6bDimensions . . . . . . . . . . . . . . . . . . . . . . . 5

Characteristics, technical . . . . . . . . . . . 4Chart,trouble-shooting . . . . . . . . . . . . . . 65Checks, amplifier:

Electrical . . . . . . . . . . . . . . . . 82, 83, 84, 85Operational . . . . . . . . . . . . . . . . . 43Shorts . . . . . . . . . . . . . . . . . . . . . . 63

Checks, audio amplifier:Electrical . . . . . . . . . . . . . . . . . . . . . . . . . 80Operational . . . . . . . . . . . . . . . . . . . . . . . 43Shorts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Circuit analysis:Amplifier . . . . . . . . . . . . . . . . . . . . 53Audio amplifier . . . . . . . . . . . . . . . . . . . 57Erase-oscillator . . . . . . . . . . . . . . . . . . . 53Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Playback . . . . . . . . . . . . . . . . . . . . . . . . . 54Power supplies . . . . . . . . . . . . . . . . . . . 56Recording . . . . . . . . . . . . . . . . . . . . . . . . 53Rewind . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Wind . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Common names . . . . . . . . . . . . . . . . . . . . 7Complement, electron tubes . . . . . . . . . 4Components table . . . . . . . . . . . . . . . . . . 5Connections:

Program line . . . . . . . . . . . . . . . . . . . . . 11 bTelephone . . . . . . . . . . . . . . . . . . . . . . . . 11 a

connectors and jacks:Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . 29aAudio amplifier . . . . . . . . . . . . . . . . . . . 29b

Controls and their uses . . . . . . . . . . . . . 28Crates, dimenaions and weights . . . . . . . 8

DData:

Electron tube . . . . . . . . . . . . . . . . . . . . 4General, maintenance . . . . . . . . . . . 60Packaging . . . . . . . . . . . . . . . . . . . . . . . . 8shipping . . . . . . . . . . . . . . . . . . . . . . . . . 97Technical . . . . . . . . . . . . . . . . . . . . . . . . 4

Definition, preventive maintenance . . . 32Demagnetizer, head . . . . . . . . . . . . . . . . 86Demolition . . . . . . . . . . . . . . . . . . . . . . . . . . 98Description, general . . . . . . . . . . . . . . . . 6Desert operation . . . . . . . . . . . . . . . . . . . . 26

32

322

57

73, 743351

733351

42474241464546424141622

119

242423

7

2497

822

2575833

21

85

Paragraph Page Paragraph Page64 51Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . 5

Disassembly:General . . . . . . . . . . . . . . . . . . . . . . . . . . 95Recorder-reproducer . . . . . . . . . . . . . . . 71

EElectrical:

Characteristics . . . . . . . . . . . . . . . . . . . . 4Performance . . . . . . . . . . . . . . . . . . . . . 43

Electron tube complement . . . . . . . . . . . . 4Equalizing amplifier V102A . . . . . . . . . 53 cEqualization circuit . . . . . . . . . . . . . . . . . 53 dEquipment:

Characteristics, technical . . . . . . . . . . 4Description . . . . . . . . . . . . . . . . . . . . . . . 6Installation . . . . . . . . . . . . . . . . . . . . . . . 10Performance check list . . . . . . . . . . . . 43Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Erase current adjustment . . . . . . . . . . . 88Erase-oscillator V107 . . . . . . . . . . . . . . . 53 h

F

Fast forward operation . . . . . . . . . . . . . 20Fast rewind operation . . . . . . . . . . . . . . 19Feedback:

Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . 54 dAudio amplifier . . . . . . . . . . . . . . . . . . . 57 b

Final teat procedures . . . . . . . . . . . . . . . 79Flutter and wow:

General . . . . . . . . . . . . . . . . . . . . . . . . . . 4Measurements . . . . . . . . . . . . . . . . . . . . . 93

Forms and records . . . . . . . . . . . . . . . . . 2Frequency:

Audio frequency range . . . . . . . . . . . 4Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . 53 hPlayback . . . . . . . . . . . . . . . . . . . . . . . . . 8 2Record . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Record playback . . . . . . . . . . . . . . . . . . 91

IInput Connections:

Microphone . . . . . . . . . . . . . . . . . . . . . . . 10Program line . . . . . . . . . . . . . . . . . . . . . 11Telephone line . . . . . . . . . . . . . . . . . . . . 11

Inspection, vised . . . . . . . . . . . . . . . . . . . . 39Installation . . . . . . . . . . . . . . . . . . . . . . . . . 10

LLamps, pilot . . . . . . . . . . . . . . . . . . . . . . .56, 58Localization, trouble . . . . . . . . . . . . . . . . 59 bLoudspeakers . . . . . . . . . . . . . . . . . . . . . . . 57Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . 35

MMaintenance:

Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36cCheck schedules . . . . . . . . . . . . . . . . . . . 34Desert . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 dTools . . . . . . . . . . . . . . . . . . . . . . . . . .. .30,31Tropical . . . . . . . . . . . . . . . . . . . . . . . . . . 36 b

Measurements, voltage and resistance:Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . 63

86

2

8266

2332

4 243

237

3 31

7543

1919

464771

2771

243737376

799

317

46, 47484729

2 92 52 92 42 9

51

Audio amplifier . . . . . . . . . . . . . . . . . . Microphone:

Description . . . . . . . . . . . . . . . . . . . . . . .Input circuit . . . . . . . . . . . . . . . . . . . . . .Recording . . . . . . . . . . . . . . . . . . . . . . . .

Monitoring:Playback . . . . . . . . . . . . . . . . . . . . . . . . .Recording . . . . . . . . . . . . . . . . . . . . . . . .

Motor:Capstan:

Operation . . . . . . . . . . . . . . . . . . . . . . .Replacement . . . . . . . . . . . . . . . . . . . .

Supply:Operation . . . . . . . . . . . . . . Replacement . . . . . . . . . . . . . . . .

Take-up:Operation . . . . . . . . . . . . . . . . . . .Replacement . . . . . . . . . . . . . . .

Mounting, rack . . . . . . . . . . . . . . . . . . . . . .

3 4113

6g5214

1817

1715

4973

4066

497 2

4066

497 210 c

40667

N

Balance adjustments . . . . . . . . . . . . . .Balance circuit . . . . . . . . . . . . . . . . . . .Ratio, signal-to-noise . . . . . . . . . . . . .

8 753 i94

754 57 9

OOscillator, erase . . . . . . . . . . . . . . . . . . . .Operation:

53 h 4 3

Arctic . . . . . . . . . . . . . . . . . . . . . . . . . . . .Desert . . . . . . . . . . . . . . . . . . . . . . . . . . .Fast forward wind . . . . . . . . . . . . . . . .Monitoring . . . . . . . . . . . . . . . . . . . . . . .Playback . . . . . . . . . . . . . . . . . . . . . . . . .Program line . . . . . . . . . . . . . . . . . . . . .Public address . . . . . . . . . . . . . . . . . . . .Recording . . . . . . . . . . . . . . . . . . . . . . . .Rewinding . . . . . . . . . . . . . . . . . . . . . . .Starting . . . . . . . . . . . . . . . . . . . . . . . . .Stopping . . . . . . . . . . . . . . . . . . . . . . . . .Telephone line . . . . . . . . . . . . . . . . . . . .

2 5262 01 7181 62 11 419132 3152720

2 12 11915171 51 91 31 91 31 91 72 119

Tropical . . . . . . . . . . . . . . . . . . . . . . . . . .Winding . . . . . . . . . . . . . . . . . . . . . . . . .

output :External loudspeaker . . . . . . . . . . . . .Headset . . . . . . . . . . . . . . . . . . . . . . . . . .Internal loudspeaker . . . . . . . . . . . . . .

18 e13 d18 d

171717

PPainting . . . . . . . . . . . . . . . . . . . . . Packaging data . . . . . . . . . . . . . . . . . . . . .Parts, replacement . . . . . . . . . . . . . . . . . .Performance checks . . . . . . . . . . . . . . . . .Performance check list . . . . . . . . . . . . . .

378

7042436

2 976632333Physical characteristics, general . . . . . .

Playback amplifier:Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . .Equalization . . . . . . . . . . . . . . . . . . . . . .Frequency response . . . . . . . . . . . . . . .Output amplifier V106 . . . . . . . . . . . .Preamplifier V104 . . . . . . . . . . . . . . . . .

5454C8 254e5 4 b

454 57 34 64 5

Paragraph Page172

SScope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sectionalizing trouble . . . . . . . . . . . . . . .Services, used or reconditioned equip-

merit . . . . . . . . . . . . . . . . . . . . . . . . . . .Shipping data . . . . . . . . . . . . . . . . . . . . . .Signal substitution:

Amplifier . . . . . . . . . . . . . . . . . . . . . . . . .Audio amplifier . . . . . . . . . . . . . . . . . . .Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Signal-to-noise ratio . . . . . . . . . . . . . . . .Splicing tape . . . . . . . . . . . . . . . . . . . . . . .Starting equipment . . . . . . . . . . . . . . . . . .Stopping . . . . . . . . . . . . . . . . . . . . . . . . . . .Symptoms, trouble . . . . . . . . . . . . . . . . . .

Playback operation . . . . . . . . . . . . . . . . . 18Playing time . . . . . . . . . . . . . . . . . . . . . . . 4 1

59 b1

48Preventive maintenance:Daily . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34aDefinition . . . . . . . . . . . . . . . . . . . . . . . . 32Forms . . . . . . . . . . . . . . . . . . . . . . . . . . 33Monthly . . . . . . . . . . . . . . . . . . . . . . . . . 34cServices . . . . . . . . . . . . . . . . . . . . . . . . . . 34Weekly . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 b

Program line, connection to . . . . . . . . . . 11Program line recording . . . . . . . . . . . . . . 16Public address:

Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Connections . . . . . . . . . . . . . . . . . . . . . . 21Operation . . . . . . . . . . . . . . . . . . . . . . . . 21

Purpose of equipment . . . . . . . . . . . . . . . 3

252525292525915

1297

1182

6968679422132365

6 3636 37919131957

3819191

TTable of components . . . . . . . . . . . . . . . .Take-up brake assembly . . . . . . . . . . . . .Tape:

Size . . . . . . . . . . . . . . . . . . . ........ .Threading . . . . . . . . . . . . . . . . . . . . . . . .

Technical characteristics . . . . . . . . . . . . .Telephone line, connection to . . . . . . . . .Test equipment . . . . . . . . . . . . . . . . . . . . .Tests, final . . . . . . . . . . . . . . . . . . . . . . . . .Theory of operation:

Amplifier:Playback . . . . . . . . . . . . . . . . . . . . . . .Recording . . . . . . . . . . . . . . . . . . . . . .

Audio amplifier . . . . . . . . . . . . . . . . . . .Recorder-reproducer . . . . . . . . . . . . . . .

Time, recording . . . . . . . . . . . . . . . . . . . .Tools, organizational and maintenanceTransformers, dc resistance . . . . . . . . .Tropical operation . . . . . . . . . . . . . . . . . .Trouble shooting:

Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . .Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Equipment performance check list . .Organizational . . . . . . . . . . . . . Precaution . . . . . . . . . . . . . . . . . . . . . .Procedures . . . . . . . . . . . . . . . . . . . . . . .Test equipment . . . . . . . . . . . . . . . . . . .

R 5 2,377 70Recording amplifier V103 . . . . . . . . . . . . 53 f

Recording:Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 hBlock diagram . . . . . . . . . . . . . . . . . . . . 45Microphone . . . . . . . . . . . . . . . . . . . . . . . 14

43

4338131522

431

4 213 134 2

11 96 1 4979 71

Program line . . . . . . . . . . . . . . . . . . . . . 16Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Record relay . . . . . . . . . . . . . . . . . . . . . . . . 53gRecords, forms and . . . . . . . . . . . . . . . . . . 2Recorder-reproducer:

Description . . . . . . . . . . . . . . . . . . . . . 6 d, 48Theory of operation . . . . . . . . . . 49, 50, 51

Rectifier:Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . 58 bAudio amplifier . . . . . . . . . . . . . . . . . . . 58 bFilament . . . . . . . . . . . . . . . . . . . . . . . . . 56 d

464557484

31662 7

3838474 02

24,256321

4040,41

464746

Recorder-reproducer . . . . . . . . . . . . . . . 49 f 40Reels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2Refinishing . . . . . . . . . . . . . . . . . . . . . . . . . 37 29 65

604331625961

57-624 9

33-3524,25

494849

Removing from service . . . . . . . . . . . . . . 95 82Repackaging and repacking . . . . . . . . . . 97 82Repacking, materials for.... . . . . . . . . . 96 82Replacement:

Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Motors:

Capstan . . . . . . . . . . . . . . . . . . . . . . . . 73supply . . . . . . . . . . . . . . . . . . . . . . . . . 72Take-up . . . . . . . . . . . . . . . . . . . . . . . . 72

Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Soundhead assembly . . . . . . . . . . . . . . . 74Tubes, electron . . . . . . . . . . . . . . . . . . . 40

32

66 UUncrating and unpacking . . . . . . . . . . . .Unusual operation . . . . . . . . . . . . . . . . . .Use of maintenance forma . . . . . . . . . . .

666666703176175 163

9 724 2133 25

VVisual inspection . . . . . . . . . . . . . . . . . . . .Voltage amplifier V102B . . . . . . . . . . . .Voltage and resistance measurements:

Amplifier . . . . . . . . . . . . . . . . . . . . . . . . .Audio amplifier . . . . . . . . . . . . . . . . . . .

Reproducer head alignment . . . . . . . . . . . 89Reproducing . . . . . . . . . . . . . . . . . . . . . . . . 18Resistance checks . . . . . . . . . . . . . . . . . . 63, 64

39 31536 43

Resistances of transformers and coils . 66Rewind:

Circuit . . . . . . . . . . . . . . . . . . . . 50

63 5164 51

41Operation . . . . . . . . . . . . . . . . . . . . . . . . . 19 19Rate . . . . . . . . . . . . . . . . . . . . . . . . . 19 c 19

Running spares . . . . . . . . . . . . . . . . . . 5 2, 3Rustproofing and painting . . . . . . . . . . . 37 29

WWeatherproofing . . . . . . . . . . . . . . . . . . . .Weights, shipping . . . . . . . . . . . . . . . . . . .Winding . . . . . . . . . . . . . . . . . . . . . . . . . . .

36 298 720 19

8 7

DEPARTMENT OF THE ARMYWASHINGTON 25, D. C., 30 January 1956

TM31-2583A is published for the use of all concerned.


Official:JOHN A. KLEIN


MAXWELL D. TAYLOR,General, United States Army,

Chief of Staff.

DISTRIBUTION:Active Army:

CNGB (1)Tec Svc, DA (1) except

Sig Lab (5)Mil Dist (1)

CSIGO (30)Tec Svc Bd (1)Hq CONARC (5)CONARC Bd (Incl enArmy AA Comd (2)OS Maj Cored (5)0S Base Cored (5)Log Cored (5)MDW(1)Armies (5)Corps (2)Tng Div (2)Ft & Cp (2)Gen & Br Svc Sch (5) except

Cig Sch (25)

Units organized under following TOE:7R, Inf Div (2)11-7R, Sig Co, Inf Div (2)11-16R, Hq&Hq Co, Sig Bn, Corps or Abn

Corps (2)11-57R, Armd Sig Co (2)11-127R, Sig Rep Co (2)11-128R, Sig Depot CO (2)11-500R (AA-AE), Sig SVc Org (2)11-557C, Abn Sig Co (2)11-587R, Sig Base Maint Co (2)11-592R Hq&Hq Co, Sig Base Depot (2)11-597R, Sig Base Depot Co (2)12-35R, Sp Band (2)12-107C, Org or Sep Band (2)

Gen Depots (2) except 17R, Armd Div (2)Atlanta Gen Depot (None) 32-51R, Hq&Hq Co, Comm Recon GP (2)

Sig See, Gen Depots (10) 32-55R, CommRecon Bn (2)Sig Depots (20) 32-56R, Hq&Hq Co, Comm Recon Bn (2)Trans Terminal Cored (2) 32-57R, Comm Recon Opr Co (2)OS Sup Agenci-(2) 32-500R (AA-AG), Comm Recon Org (2)Sig Fld Maint Shops (S) 33-77R, Loudspeaker and Leaflet Co, Army (2)

NC: State AG (6) ; Units— Same as Active Army except allowance is one copy to each unit.USAR: None.For explanation of abbreviations used, see SR 320-50-1.

U.S. GOVERNMENT PRINTING OFFICE: IWZ - 311401/44S028 8

Figure 48. Audio amplifier, schematic diagram.

TM2583A-20

TM2583A-19

Figure 49. Amplifier, schematic diagram.

TM2583A-

Figure 50. Recorder-reproducer, schematic diagram.

TM2583A-50

Figure 51. Audio amplifier, wiring diagram.

TM2583A-52

Figure 52. Amplifier, wiring diagram.

Figure 53. Recorder-reproducer, wiring diagram.

TM2583A-51

PIN : 028942-000

This fine document...

Was brought to you by me:

Liberated Manuals -- free army and government manuals

Why do I do it? I am tired of sleazy CD-ROM sellers, who take publicly available information, slap “watermarks” and other junk on it, and sell it. Those masters of search engine manipulation make sure that their sites that sell free information, come up first in search engines. They did not create it... They did not even scan it... Why should they get your money? Why are not letting you give those free manuals to your friends?

I am setting this document FREE. This document was made by the US Government and is NOT protected by Copyright. Feel free to share, republish, sell and so on.

I am not asking you for donations, fees or handouts. If you can, please provide a link to liberatedmanuals.com, so that free manuals come up first in search engines:

<A HREF=http://www.liberatedmanuals.com/>Free Military and Government Manuals</A>

– SincerelyIgor Chudovhttp://igor.chudov.com/

– Chicago Machinery Movers

http://www.liberatedmanuals.com/

https://www.machinerymoverschicago.com/

http://igor.chudov.com/

http://www.liberatedmanuals.com/

Documents

SOUND RECORDER- REPRODUCER SET · Changes in force C1, C2, C4, C6, C7, and C8 Change No. 8 TM 11-2583A C8 HEADQUARTERS DEPARTMENT OF THE ARMY Washington, D.C.,5 November 1973 SOUND