Service Manual Video CassetteRecorder

VHR-240 seriesVHR-250 seriesVHR-251 seriesVHR-254 seriesVHR-24 seriesVHR-27 series

Illustration: VHR-250G

prigPAL

TABLE OF CONTENTS

1. CIRCUIT BOARD LOCATIONS

1-1. MAINBOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1-2. LOCATION FOR TAPE PATH ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2. ELECTRICAL ADJUSTMENT

2-1. PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2-2. SERVO CIRCUIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2-3. VIDEOCIRCUIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...6

2-4. VIDEOTEXTDECODER CIRCUIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2-5. AUDIOCIRCUIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2-6. TUNER lFCIRCUIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3. DISASSEMBLY PROCEDURES

3-1. REMOVAL OF REMOTE CONTROL UNITCASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..l0

EP4,EP4Vseries REFERENCE No. WM-531058

351lL1 l(N)

I

1. CIRCUIT BOARD LOCATIONS

1-1. MAIN BOARDS

Video pre-amp unit

7

/

(

CP-1 (Video, Servo & Audio) boardW-lPowersupply)hard&~GMl

,:,, ‘ ... .

TM-2 (Operation) board

“ my*M~fld-eboadTM-1 (Operation key & Display) board

Installed specific-equipment and modelsTM-5 (OSA: on screen assist) board: except VHR-254GTM-6 (Videotext decoder) board: VHR-254G onlyTM-8 (VPS) board: VHR-240G, VHR-250G, VHR-254G

Appearance and specifications are subject to change without notice.

Figm 1-1

~ TM-8 (VPS) board

L13L073

1-2. LOCATION FOR TAPE PATH ADJUSTMENT

NOTE: Test point TP182 and TPI 83 for tape path adjustment is shown in figure below.

For adjustment, refer to the Mechanism Service Technical Information (WM-530599 and WM-531 029).

FOSL012

Shield case

F o m .I-@RqJq

s

r

TP183 TP182 CN181SW-P. ENV.

Fig. 1-2 Video pre-amp unit

—

—l—

3511J11(N)

2. ELECTRICAL ADJUSTMENTL

2-1. PREPARATION When repairing the Video pre-amp unit

2-1-1. EQUIPMENT (see Figs. 2-1-1 and 2-1 -4)

Colour TV monitorPAL Colour-bar generator (with RF and LINE OUTPUT)

Audio signal generator

Oscilloscope (dual trace; frequency response: 10MHZ or

more; probe: 101 )Frequency counter (countable to 10MHZ or higher)

Digital voltmeterAC voltmeter

In/output probes

Alignment cassette (VHJ-0008) PAL Colour bar 1KHz

Alignment cassette (VHJ-0009) Monoscope 6KHz

Alignment cassette (VHJ-0023) PAL Monoscope 6KHz,PAL Colour-bar 1KHz, SECAM Colour-bar 1KHz, PAL RF

Sweep MESECAM Colour-bar 1KHz, NTSC Colour-bar1KHz.

Relay jig (vHJ-0066) 7-wire cable for Pre-amp unit

Relay jig (VHJ-0084) for CP-1 and CP-2 board

Relay jig (VHJ-0085) for Video pre-amp unit

2-1-2. CONNECTING THE RELAY JIG

When repairing CP-1

(see Figs. 2-1-2 and 2-1 -3)

NOTE: The connection of any Relay jigs can be done with-

1.

2.

3.

4.

5.

6.

out removing the front panel of the main unit.Remove the seven red screws of the CP-1 board to take

out.Insert the CP- 1 board in the slit of chassis as shown in

Fig. 2-1-3.

Connect CNO1 and CN02 of Relay jig (VHJ-0084) into

connectors of the PW-1 board and the Pre-amp unit, in the

direction of arrow as shown in Fig. 2-1-3. Fix the Relay jig(VHJ-0084) with screw if necessary.

Connect 12-pin, 8-pin and 4-pin connectors of the Relayjig to connectors CN541, CN101 and CN201 on the CP-1

board, respectively.Connect connector from ACE head to CN06 of the Relayjig (VHJ-0084).

After finishing the repairs and adjustments, put the Flat

cables (A) and (B) back to its former position.

CN08 connectorfrom

CN02 connectorto connectorforACEhead

CN181 of Pre-amp unit. \

1. Remove the Pre-amp unit from the chassis, connect

Relay jig (vHJ-0066) between the Pre-amp unit and

cylinder assembly.2. Connect Relay jig (VHJ-00B4) excepting 8-pin connector

between the PW- 1 board and CP-1 board as shown inFig. 2-1-4. Fix the Relay jig (VHJ-0084) with screw if

necessary.3. Connect Relay jig (VHJ-0085) between the top of Pre-

amp unit and CN101 on the CP-1 board.

NOTE: When repairing or adjusting the Pre-amp unit, be

sure to make contact an end of the Shield casewith Bracket of the Pre-amp unit to maintain the

shield effect. If the Pre-amp unit does not contact,image can be obtained.

CAUTION: Be sure that the Relay jig does not have touchwith video head or the upper cylinder assem-

bly.

CN02 connector toCN181 of Pre-amp unit

8-pin connector toCN101 of CP-1 board

Relay jig VHJ-0085

Fig. 2-1-1

‘eaw’’’’’’’’aCNO1 connector toCN511 of PW-1 board

Relay jig VHJ-0084b

4-pin connector toCN201 of CP-1 board

Fig. 2-1-2

—2—

3511J21(N)

P1OJO17

Connector to CN06 1 r 12-pinconnector to CN541

v!!!&’* ‘~

1“

w’— \

Relay jig (VHJ-O064)–

Screw7

CNO1 toCN511 of PW-1 board

CN06 for connector from ACE head 4-pin connector to CN201

ACE head Flat cable B (35-wires)

~ II I!_ -!

Fig. 2-1-3

WSJO18

ector

Vtdeo pre nector

Relay jig

Syli

Fig. 2-1-4

2-1-3. SET-UPBecause the RF input signal is used for circuit adjustments,connect the colour-bar generator to the ANT IN terminal of

the VCR. The RF input signal is processed by the tuner andIF circuit. It is improtant that the video output signal of the IF

circuit satisfies the items shown in Fig. 2-1-5. Connect the

oscilloscope to the VIDEO OUTPUT terminal of the videocircuit and terminate with a 75Q load, and then check the

video output signal..

.

.

The amplitude of the sync signal should be approxi-

mately 0.3 Vp-p.The amplitude of the video signal should be approxi-

mately 0.7 Vp-p.

While observing the oscilloscope or TV screen, make

fine-tuning adjustments so that the colour burst

amplitude is approximately 0.3 Vp-p. !--

Check to be sure that there is no spike noise in the syncpart of the horizontal sync signal.

W05JO01

100%

P

o.

-P

H syncsignal

Fig. 2-1-5

–3–

3513S11(N)

2-2. SERVO CIRCUIT ADJUSTMENT

o These adjustments should be carried out upon completion of the tape transport adjustments.

o If the tape transport adjustments (except the tilt adjustment) are carried out after these adjustments, follow the procedures

again in Item 1 SWITCHING POSITION ADJ.

“ When a cassette tape is loaded, auto-tracking will be set immediately after starting the first playback. As this will deviate the

tracking center set, be sure to press tracking buttons (+) or (-) once directly after starting playback to prevent auto-tracking from

being set. Press the tracking buttons (+) and (-) simultaneously, the tracking control to the center position.

“ Unless otherwise specified, all test point and adjustment location on the CP- 1 board.

io. Item Input Mode Point Location Remark

W25SO01

%:?in’y+

VIDEOOUTPUT

Alignment TP101Videosignal

cassette J654321—, SWITCHING V sync

POSITION(VHJ-0009 PLAY RF SW VR351

pulse 1. Press the tracking buttons (+) and (-) simul-VHJ&23) TPI 83 taneously to the tracking center position (in-

(Video pre- dictor panel displayed: “T —:— “).amp unit) 2. Adjust VR351 so that the phase of the lead-

ing edge of the vertical sync signal is delayed6.5 &0.5 H from the rise of the RF switchingpulse waveform.

W20S011

E

Noiseat — ------ ------ -----.---- -------- - Monitor------- --------upperside screen

Noise at-----.---- ----------- ------- --- lower side----------- ----

1. Set the VCR in the SP REC mode and recordat the middle of the cassette tape.

2. Playback the recorded part, and set the SPSTILL mode.

3. Press the tracking buttons (+) or (-) until V

SP modejitter (very fine movement of the vertical

RECsync.) is minimized.

Colour bar !TRACKING 4. Set the SP SLOW mode by remote control unit.

buttons 5. Press the tracking buttons (+) and (-) simul-SP SLOW from PIAY

2 TRACKING Colour bar \TV screen and taneously to adjust the tracking to the center

generator STILLREC button position (displayed: “T —:— “).

\(Front panel) Press the REC button during the tracking

SLOWcenter display (approx. within three sec-onds), at this time make sure that display asshown “T- : —“.

6. Press tracking buttons(+) or (-) to send awaythe noise which appears on the monitorfrom the screen, and also adjust the positionof the noise at the upper side of the screen tothe similar position of the one at the lowerside judging from the center of the screen.Press the REC button during the trackingcenter display (approx. within three sec-onds), at this time make sure that display asshown ‘T— : —“.

—4—

- ..”-..,., .

S51.XIZI(NI

]

10, Item Input Mode Point Location Remark

W20S011

E

Noise at — :.-::::.-::::::::- Monitor------ -------- .upper side screen

Noise at------ ------- ------- . . . . . ------ Iower side----- ------ ..-.

1.Set the VCR in the LP REC mode and record atthe middle of the cassette tape.

2. Playback the recorded part, and set the LPSTILL mode.

3. Press the tracking buttons(+) or (-) until V jitter(very fine movement of the vertical sync.) is

LP modeminimized.

REC4. Set the LP SLOW mode by remote control unit.

Colour bar ITRACKING 5. Press the tracking buttons (+) and (-) simul-

LP SLOW from PIAYbuttons taneously to adjust the tracking to the center

3 TRACKING Colour barTV screen and position (displayed: “T —:— “).

generator ST:LLREC button Press the REC button during the trakcing

(Front panel) center display (approx. within three seconds),

SL~Wat this time make sure that display as shown‘l–– : –“.

6, Press tracking buttons (+) or (-) to send awaythe noise which appears on the monitor fromthe screen, and also adjust the position of thenoise at the upper side of the screen to thesimilar position of the one at the lower sidejudging from the center of the screen.Press the REC button during the trackingcenter display (approx. within three seconds),at this time make sure that display as shown“T– : –“.

Note: Skew may occur at the upper side of theplayback monitor screen during the LPmode, do not mistook this for noise.

PI 2S051

1

TB-1

TP201 (HOT).~--1~--:; ICI 11 Terminal

TP202 (GND)@ ::II

r--; VR20111

0

@ BIAS TP101 ~~

IC301 VIDEOOQ1012 OUT ‘‘

II.-.

CN302 r-,.----------------, II\-_-- _---- __--. -l

L.,’II

~----------->! ~ ------------------ .,

L-_------ _-: .Tuner ~ ~ ~,-. .. i: IL_-- _------ _—_----J

L--_j

Fig. 2-2-1 CP-I board (Foil side view)

—5–

3513V11(N)

2-3. VIDEO CIRCUIT ADJUSTMENT

“ Use the Relay jig mentioned in the 2-1. PREPARATION to provide simple adjustment of the Video Pre-amp unit.o Before these adjustments place the unit in the SP mode.

- Unless otherwise specified, alltest point and adjustment location on the CP-1 board.

Item

AGC

LEVEL

PB-YLEVEL

CARRIERSET

DEVIATION

Input

Colour bar100% white

level)from

Colour bargenerator

Alignmentcassette

[VHJ-0008

VHJ:b23)

Colour bar100% whitelevel) fromColour bargenerator

1No-signal

Colour bar100% white

level)from

Colour bargenerator

Mode

E-E

PLAY

REC

REC(Adjust-

ment)i

PIAY(Check)

Point

TP102

VIDEOOUTPUTTP101

TPI 03

VIDEOOUTPUTTP101

Location

VR102

VR101

VR103

VR104

Remark

-100% whitew25v03(

J’54E!,*u____._i

1. Terminate VIDEO OUTPUT terminal with a75 ohms.

2. Adjust VRI 02 so that the level is 0.50*0.025 Vp-p.

W25VC0

~1 00% white

* 0.05 v,-,

1. Terminate VIDEO OUTPUT terminal with a75 ohms.

2. Adjust VR101 so that the level is 1.00 *0.05 Vp-p.

1.

2.

3.

Input the PAL colour bar signal to VIDEOINPUT terminal.Set the channel selector buttons to the 8’AV’position and put the VCR in the REC mode.After removing the first colour bar signal

input from the video input terminal, imme-

diately adjust VR103 so that the frequency

becomes 3.83 * 0.05 MHz.

- 100% white

* 0.05 v,-,

1. Terminate VIDEO OUTPUT terminal with a75 ohms.

2. Insert the blank tape to the VCR and recordcolour bar signal.

3. Playback the recorded part, and check thatthe level is 1.00* 0.05 Vp-p.

4. If the adjustment value is not satisfactory,adjust VR104 and repeat step 3.

—6—

3511V21(N)

—

10—

5

—

6

—

Item

C RECCURRENT

Y RECCURRENT

Input

Colour barfrom

Colour bargenerator

Colour barfrom

Colour bargenerator

Mode

REC

REC

Point

rP181 (HOT)Shield case

(GND)(Video pre-amp unit)

rpl 81 (HOT)Shield case

(GND)(Video pre-amp unit)

Location

VR181(Video pre-amp unit)

VR182(Video pre-amp unit)

Remark

WI 5VO06

t150 * 5 mVp-p

i

1.

2.

Rotate VR182 so that the luminance level isminimize.Adjust VR181 so that the signal level is 150* 5 mVp-p.

W25V028

T

480 + 20 mVp-p

A

II II+t- --it

H sync H sync

1. Connect the ground of the oscilloscope tothe Shield case of Video pre-amp.

2. Set the channel selector buttons to the AVposition.

3. Adjust VRI 82 so that the signal level at thesync tip is 480 f 20 mVp-p.

Posvol2

Shield caseVR181 VR 182

4p 0? ‘Ekd+TP181 CN181

I Fig. 2-3-1 Video pre-amp unit

.-

.. .. .

—7—

3519X11(N)

2-4. VIDEOTEXT DECODER CIRCUIT ADJUSTMENT... For VHR-254G only

—.

“ Unless otherwise specified, all test point and adjustment location on the TM-6 board.

Uo. Item Input Mode Point Location Remark

1.Set the vartical scale (VOLTAGE/DIV.) ofthe oscilloscope to 10 mV/DIV..

2. Connect the frequency counter to Emitter ofEmitter of QIO12 and ground through a pre-amp of

1DECODER

NONE E-EQIO12

CT771the above oscilloscope.

V)(O (CP-1 board) 3. Press the “MENU” button on the remoteFig. 2-2-1 control unit.

4. After the frequency off by turning CT771 formoment. Adjust CT771 so that the frequen-cy is 4433619 * 50 Hz.

Ploxolo

J

Fig. 2-4-1 TM-6 board (Pam side view)

i-..:>.: ... . . . .. ,>.... ... ,.~...<

—8–

3511A11(N)

2-5. AUDIO CIRCUIT ADJUSTMENT

“ Unless otherwise specified, all test point and adjustment location on the CP-1 board.

No. Item Input

1BIAS

LEVELNo-signal

Remark

1. Set the channel selector buttons to the AVposition and place in the SP record modewithout a signal.

2. Adjust VR201 so that the level is 23 mVrms.3. Confirm that the bias frequency is 70 * 5

KHz.

Mode

REC

Point

TP201 (HOT)TP202 (GND)

Location

VR201

2-6. TUNER IF CIRCUIT ADJUSTMENT

“ There are two of the VIF unit’s type and different with the model as shown in figure below.

—

10—

1

—

Item Input Mode Point Location Remark

1. Receive the middle electrical field (60 dB -80 dB) of the TV channel, and slowly turnVR611 from the point where snow-noise ispresent to the point where it just disappearsfrom the monitor TV.

2. Confirm by monitor TV that there is no beatand saturation (S/N is best point) when re-ceiving any TV channel.

Wbroadcast

VR611

(VIF unit)RF AGC E-E TV screen

POSUO06,.

VR611 &RF AGC

B

:11

CP-1 board

w . . . . . . . . . .

CP-1 board

~z..< . . . ..r.> . . ..r..—.z . . . .

TYPE BTYPE A

Fig. 2-6-1 VIF unit (Parts side view)I

,~.

—9–

3502B11(N)

3. DISASSEMBLY PROCEDURES

kiik.- fL,=

3-1. REMOVAL OF REMOTE CONTROL UNIT CASEOpen the remote control unit case as follows. Although a

large type remote control unit is shown in the figure bellow,small type remote control unit can be openad by the sameprocedures.NOTE: When opening the remote control unit for repairing,

use a GUITER PICK made of plastic (1 mm thickness) shown

in the Fig. 3-1-2 or the like (a thin plastic piece) to prevent

scratching.

Never use a metal screwdriver to avoid scratching.

1. Open the battery cover and take out batteries, the then

remove the bottom case fixing screw.

2. Applying force strongly to the battery compartment edge

in the arrow (A) direction by your thumb as shown in Fig.

3-1-1 to make a space (B) between the bottom and upper

case as shown in the cross section Fig. 3-1-3.

m7aool

Edge

r

\’

Make a space [B)

/

$

Batterycompartment

Bottom case

7

‘%Upper case

Fig. 3-1-1

FQ7aoos

a

GUITER PICK orThin plastic piece

Fig. 3-1-2 Make a space [B)

r#~

;;;ER“>/,.

\\

Hooks (F)

Bonom caseUpper case

Fig. 3-1-3

To make this procedure easier, push the remote control

unit end (C) against your body Fig. 3-1-4.3. Insert the GUITER PICK above mentioned into the space

(B) as shown in Figs. 3-1-3,3-1-4 and move the PICK inthe arrow (D) and (E) direction, then disconnect two hooks

(F) of the top of the cases.4. Applying force to the space (B) and battery compartment

edge by your thumb so that the bottom case is separatedfrom the upper case as shown in the Fig. 3-1-5.

5. Insert the PICK into the space(G) of the case side slanting-ly against the bottom case and move the PICK to

disconnect the hooks (H) of the side in order from top to

bottom Fig. 3-1-5.

6. Disconnect the hooks of the other side using the pick by

the same procedure as step 4.

F07BO02

ER PICK

c

Fig. 3-1-4

m7aoo4Keep a space (B)

K

H)

Fig. 3-1-5

—lo—

,-

Apr.Z92/57m HA PrintedinJapan

SANYO Electric Co., Ltd.Osaka, Japan