4317340 KAC-36 KitchenAid Over-The-Counter Microwave Oven

TECHNICAL EDUCATION

KAC-36

JOB AID 4317340

OVER-THE-COUNTER

MICROWAVE OVEN

Model KOMS155MBL

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Copyright © 2003, Whirlpool Corporation, Benton Harbor, MI 49022

FORWARDThis KitchenAid Job Aid, “Over-The-Counter Microwave Oven,” (Part No. 4317340), provides thetechnician with information on the installation, operation, and service of the Over-The-CounterMicrowave Oven. It is to be used as a training Job Aid and Service Manual. For specific informationon the model being serviced, refer to the “Use and Care Guide,” or “Wiring Diagram” provided withthe microwave oven.

The Wiring Diagrams used in this Job Aid are typical and should be used for training purposes only.Always use the Wiring Diagram supplied with the product when servicing the unit.

GOALS AND OBJECTIVESThe goal of this Job Aid is to provide detailed information that will enable the service technician toproperly diagnose malfunctions and repair the KitchenAid Over-The-Counter Microwave Oven.

The objectives of this Job Aid are to:

• Understand and follow proper safety precautions.

• Successfully troubleshoot and diagnose malfunctions.

• Successfully perform necessary repairs.

• Successfully return the microwave to its proper operational status.

WHIRLPOOL CORPORATION assumes no responsibility for any repairs madeon our products by anyone other than Authorized Service Technicians.

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TABLE OF CONTENTSPage

GENERAL ............................................................................................................................... 1-1Safety First ......................................................................................................................... 1-1Warning To Service Technicians ....................................................................................... 1-4Precautions To Be Observed Before And During Servicing To Avoid Possible Exposure To Excessive Microwave Energy ...................................... 1-5R.F. Leakage Test ............................................................................................................. 1-6Precautions To Be Observed When Troubleshooting ....................................................... 1-7KitchenAid Model & Serial Number Designations.............................................................. 1-8Model & Serial Number Label And Wiring Diagram Locations .......................................... 1-9Specifications................................................................................................................... 1-10KitchenAid Microwave Oven Warranty ............................................................................ 1-12

INSTALLATION INFORMATION ........................................................................................... 2-1Removing The Microwave Oven........................................................................................ 2-1

THEORY OF OPERATION ..................................................................................................... 3-1Microwave Operating Sequence........................................................................................ 3-1The Absolute Humidity (AH) Sensor Circuit ....................................................................... 3-4

COMPONENT ACCESS ......................................................................................................... 4-1Component Locations ........................................................................................................ 4-1Removing The Cabinet ...................................................................................................... 4-2Removing The Control Board ............................................................................................ 4-3Removing The Door Interlock Switch Assembly ................................................................ 4-4Removing The Line Fuse And Oven Lamp........................................................................ 4-6Removing An Accent Or Task Lampholder And The Turntable Motor .............................. 4-7Removing The Humidity Sensor & Cavity Temperature Fuse ........................................... 4-8Removing The Magnetron Temperature Fuse And The Magnetron ................................ 4-10Removing The High Voltage Capacitor & Diode, And The Cooling Fan Motor ............... 4-12Removing The High Voltage Transformer ....................................................................... 4-15Removing The Oven Door Assembly .............................................................................. 4-16Removing The Oven Door & Control Panel And The Display Assembly ......................... 4-18

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COMPONENT TESTING ........................................................................................................ 5-1Door Switches.................................................................................................................... 5-1Turntable Motor ................................................................................................................. 5-2HV Capacitor ..................................................................................................................... 5-2Humidity Sensor ................................................................................................................ 5-3Cavity & Magnetron Temperature Fuses ........................................................................... 5-3Line Fuse ........................................................................................................................... 5-4Cooling Fan Motor ............................................................................................................. 5-4High Voltage Transformer.................................................................................................. 5-5High Voltage Diode ............................................................................................................ 5-5Magnetron.......................................................................................................................... 5-6

DIAGNOSIS & TROUBLESHOOTING ................................................................................... 6-1Troubleshooting ................................................................................................................. 6-1Touch Control Panel Assembly Test ................................................................................. 6-2Key Unit Test ..................................................................................................................... 6-3Relay Test .......................................................................................................................... 6-4Defrost Center Test ........................................................................................................... 6-5Absolute Humidity (AH) Sensor ......................................................................................... 6-6

WIRING DIAGRAMS .............................................................................................................. 7-1Schematic Diagram ........................................................................................................... 7-1Wiring Diagram .................................................................................................................. 7-2

Page

1-1

GENERAL

Electrical Shock Hazard

Plug into a grounded 3-prong outlet.

Do not remove ground prong.

Do not use an adapter.

Do not use an extension cord.

Failure to follow these instructions canresult in death, fire, or electrical shock.


Disconnect power before servicing.

Replace all parts and panels beforeoperating.

Failure to do so can result in death orelectrical shock.

SAFETY FIRST

Your safety and the safety of others is very important.

We have provided many important safety messages in this Job Aid and on the appliance. Alwaysread and obey all safety messages.

This is the safety alert symbol.This symbol alerts you to hazards that can kill or hurt you and others.All safety messages will follow the safety alert symbol and either the word“DANGER” or “WARNING.” These words mean:

All safety messages will tell you what the potential hazard is, tell you how to reduce thechance of injury, and tell you what can happen if the instructions are not followed.

You can be killed or seriously injured if you don’timmediately follow instructions.

You can be killed or seriously injured if you don’tfollow instructions.

ELECTRICAL POWER SUPPLY &GROUNDING REQUIREMENTS

1-2


Connect green ground wire to groundscrew.



Improper use of the grounding plug canresult in a risk of electrical shock.

Before touching any oven component or wir-ing, always unplug the oven from its powersource and discharge the high voltage capaci-tor (see page 4-12).

Check that the unit is grounded before trouble-shooting. Be careful of the high voltage circuits.Discharge any static charge from your body bytouching ground before handling any part ofthe circuitry on the control board. Electrostaticdischarge may damage the control circuit.

Do not touch oven components or wiring duringoperation. Attach meter leads with alligatorclips when making operational tests.

For continued protection against radiationemission, replace only with these types ofswitches: Primary (Interlock) Switch: SZM-V16-FA-63 or VP-533A-OF; Secondary (Interlock)Switch: SZM-V01-FA-32; Interlock (Monitor)Switch: SZM-VI6-FA-62 or VP-532A-OF; OvenLamp Switch: SZM-V6-FA-31 or VP-331 A-OD.

It is neither necessary nor advisable to attemptmeasurement of high voltage.

Attaching the adaptor ground terminal to thewall receptacle cover screw does not groundthe appliance unless the cover screw is metaland not insulated and the wall receptacle isgrounded through the house wiring.

The microwave oven must be grounded. In theevent of an electrical short circuit, groundingreduces the risk of electrical shock by providingan escape wire for the electrical current. Themicrowave oven is equipped with a cord havinga grounding wire with a grounding plug. Theplug must be plugged into an outlet that isproperly installed and grounded.

Consult a qualified electrician or serviceman ifthe grounding instructions are not completelyunderstood, or if doubt exists as to whether themicrowave oven is properly grounded. Do notuse an extension cord. If the power supply cordis too short, have a qualified electrician orserviceman install an outlet near the micro-wave oven.

1-3

ELECTROSTATIC DISCHARGE(ESD) SENSITIVE ELECTRONICS

ESD problems are present everywhere. ESDmay damage or weaken the electronic controlassembly. The new control assembly may ap-pear to work well after repair is finished, butfailure may occur at a later date due to ESDstress.

• Use an antistatic wrist strap. Connect thewrist strap to a green ground connectionpoint or unpainted metal in the appliance; ortouch your finger repeatedly to a green groundconnection point or unpainted metal in theappliance.

• Before removing the part from its package,touch the antistatic bag to a green groundconnection point or unpainted metal in theappliance.

• Avoid touching electronic parts or terminalcontacts. Handle the electronic control as-sembly by the edges only.

• When repackaging the failed electronic con-trol assembly in an antistatic bag, observethe above instructions.

1-4

To avoid possible exposure to microwave ra-diation or energy, visually check the oven fordamage to the door and door seal beforeoperating any oven. Use a microwave surveymeter to check the amount of leakage beforeservicing. In the event the R.F. Ieakage ex-ceeds 4 mw/cm2 at 5 cm, appropriate repairmust be made before continuing to service theunit. Check interlock function by operating thedoor latch. The oven cook cycle should cut offbefore the door can be opened.

The door and latching assembly contains theradio frequency energy within the oven. Thedoor is protected by three safety interlockswitches. Do not attempt to defeat them.

Under no circumstances should you try tooperate the oven with the door open.

• Proper operation of microwave ovens re-quires that the magnetron be properlyassembled to the waveguide and cavity.Never operate the magnetron unless it isproperly installed.

• Be sure the “RF” seal is not damaged andis assembled around the magnetron domeproperly when installing the magnetron.

• Routine service safety procedures shouldbe exercised at all times.

• Untrained personnel should not attemptservice without a thorough review of testprocedures and safety information con-tained in this Job Aid.

WARNING TO SERVICE TECHNICIANS

KitchenAid microwave ovens have a monitor-ing system designed to assure proper opera-tion of the safety interlock systems.

The monitor switch will immediately cause theoven fuse to blow if the door is opened and theprimary door interlock switch and/or the sec-ondary interlock switch contacts fail in a closedposition.

CAUTION: Replace a blown fuse with a 20ampere class H fuse only.

Test the upper and lower door interlockswitches, cook relay, and monitor switch (middleswitch) for proper operation as described in thecomponent test procedures, before replacingthe blown oven fuse.

Do not attempt to repair sticking contactsof any interlock switch, safety switch, orCook (Latch) relay. The components mustbe replaced.

Any indication of sticking contacts during com-ponent tests requires replacement of that com-ponent to assure reliability of the safety inter-lock system.

If the fuse is blown, the Monitor switch, andthe Primary, and Secondary interlockswitches must be replaced. Be sure theyare properly connected.

1-5

PRECAUTIONS TO BE OBSERVED BEFORE AND DURINGSERVICING TO AVOID POSSIBLE EXPOSURE

TO EXCESSIVE MICROWAVE ENERGY

A. Do not operate or allow the oven to beoperated with the door open.

B. Make the following safety checks on allovens to be serviced before activating themagnetron or other microwave source,and make repairs as necessary:

1) Interlock Operation

2)Proper Door Closing

3)Seal and Sealing Surfaces (Arcing,Wear, and Other Damage)

4)Damage to or Loosening of Hinges andLatches

5) Evidence of Dropping or Abuse

C. Before turning on the microwave powerfor any service test or inspection within themicrowave generating components, check

the magnetron, wave guide or transmis-sion line, and cavity for proper alignment,integrity, and connections.

D. Any defective or misadjusted componentsin the interlock, monitor, door seal, andmicrowave generation and transmissionsystems shall be repaired, replaced, oradjusted, using procedures described inthis Job Aid, before the oven is released tothe owner.

E. A microwave leakage check to verify com-pliance with the Federal Performance Stan-dard should be performed on each ovenprior to release to the owner.

F. Do not attempt to operate the oven if thedoor glass is broken.

1-6

R.F. LEAKAGE TEST

EQUIPMENT

• Electromagnetic energy leakage monitor(NARDA 8100B, HOLADAY H 1501 ).

• 275 ±15 ML glass beaker.

TEST

On every service call, checks for microwaveenergy emission must be made according tothe following manner.

1. Remove the cooking rack from the ovencavity, if the microwave oven is soequipped.

2. Place a 275 ±15 ML (9.3 oz.) glass ofwater in the center of the oven bottom.

3. Select "HIGH" cook power, turn the micro-wave oven on, and test for R.F. Ieakage atthe following locations:

a)Around the cabinet at the front.b)Around the door.c) Across the console panel.d)Horizontally across the door.e)Vertically across the door.f) Diagonally across the door.g)Across the air vents.h)Across the rear air vent.i) All lockseams.j) Weld at bottom.k) Bottom plate.I) Oven feet.

4. The scan speed is one inch per second.

When checking for R.F. Ieakage, use an ap-proved R.F. measuring device to assure lessthan 4 mw/cm2 emission at 5 cm distance witha maximum scan rate of 2.54 cm/second, incompliance with U.S. Government Departmentof Health, Education and Welfare 21CFR1030,Performance Standard for Microwave Ovens.

A properly operating door and seal assemblywill normally register small emissions, but theymust be no greater than 4 mw/cm2 to allow formeasurement uncertainty.

NOTE: Enter leakage readings in space BE-FORE and AFTER on the service document.

All microwave ovens exceeding the emissionlevel of 4 mw/cm2 must be reported to Dept. ofService for Microwave Ovens immediately andthe owner should be told not to use the micro-wave oven until it has been repaired com-pletely.

If a microwave oven is found to operate with thedoor open, report to Dept. of Service, themanufacturer and CDRH* immediately. Alsotell the owner not to use the oven.

The monitor switch acts as the final safetyswitch protecting the customer from micro-wave radiation. If the monitor switch operatedto blow the fuse when the interlocks failed, youmust replace all interlock switches with newones, because the contacts of those interlockswitches may be melted and welded together.

If safety interlock/monitor switch replacement,or adjustment, is required, you must reconnectthe circuit, and perform a continuity check onthe monitor circuit.

All repairs must be performed in such a mannerthat microwave energy emissions are minimal.

Address for CDRH is:

Office of Compliance (HFZ-312) Center forDevices and Radiological Health1390 Piccard DriveRockville, MD 20850

* CDRH: Center for Devices and Radiological Health,Food and Drug Administration.

1-7

PRECAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING

WARNING

DISCHARGING HIGHVOLTAGE CAPACITORS

For about 30 seconds after the oven isturned off, an electric charge remains in thehigh voltage capacitor.

When replacing or checking parts, removethe power plug from the outlet. Use a20,000Ω, 2 watt resistor, and short the ca-pacitor terminal to chassis ground to dis-charge it. Be sure to touch the chassis groundfirst, and then touch the capacitor terminal.

The microwave oven is a high voltage, highcurrent appliance. It is free from danger duringordinary use, but extreme care should be takenduring repair.

CAUTION

Service technicians should remove theirwatches whenever working close to or re-placing the magnetron.

WARNING

Never touch any circuit wiring with yourhand, or with an insulated tool during opera-tion.

WARNING

Never insert a wire, nail, or any other metalobject through the lamp holes on the cavity,or any other holes or gaps. Doing so may actas an antenna, and cause microwave leak-age.

WARNING

Before touching any oven components orwiring, always unplug the oven from itspower source, and discharge the capaci-tors in the high voltage section of the mi-crowave oven.

1-8

KITCHENAID MODEL & SERIAL NUMBER DESIGNATIONS

MODEL NUMBER

SERIAL NUMBER

MODEL NUMBER K OM S 1 5 5 M BL 0INTERNATIONAL SALES IND.OR MARKETING CHANNELIF PRESENTPRODUCT GROUP K = KITCHENAID BRANDPRODUCT IDENTIFICATION BH = BUILT-IN HIGH-SPEED OVEN BM = BUILT-IN MICROWAVE CM = COUNTERTOP MICROWAVE OM = OVER THE COUNTER MICROWAVEMERCHANDISING SCHEME S = STANDARD C = MICRO-CONVECTIONCAPACITY / SIZE / SERIES / CONFIGURATION 05 = 0.5 CU FT 08 = 0.8 CU FT 10 = 1.0 CU FT 13 = 1.3 CU FT 15 = 1.5 CU FTFEATURES 2 = PLUS FEATURES 5 = DELUXE FEATURES 6 = MICRO-CONVECTION 7 = MICRO-CONVECTION WITH SENSOR S = CARRY-IN WARRANTY (EFFECTIVE 02/96) X = IN-HOME WARRANTY (EFFECTIVE 02/96) YEAR OF INTRODUCTION M = 2003COLOR CODE WH = WHITE, BL = BLACK, BT = BISCUIT, SS = STAINLESS STEELENGINEERING CHANGE (0, 1, 2, ETC.)

SERIAL NUMBER X S P 3 8 1 0 0 0 6DIVISION RESPONSIBILITY XS = OXFORDYEAR OF PRODUCTION P = 2003WEEK OF PRODUCTION 38TH WEEKPRODUCT SEQUENCE NUMBER

1-9

MODEL & SERIAL NUMBER LABELAND WIRING DIAGRAM LOCATIONS

The Model/Serial Number label and Wiring Diagram locations are shown below.

Model & SerialNumber Label Location

Wiring Diagram Location (Inside Right Side Of Cabinet)

1-10

SPECIFICATIONSMODEL KOMS155MBL / WH/BT/SSDimensions/Specifications

Colors WH = White, BL = Black , BT = Biscuit, SS = Stainless

Outside Dimensions 23 7/8" W X 14 1/16" H X 15 9/16"D

Interior Cavity Dimension 17 1/2" W X 9 7/8" H X 14 5/16"DCONTROL SYSTEMPower Levels Yes-2Timer Yes Type Electronic Limits 99 Min. 99 Sec. Scale Linear (Digital) Operation Touch Control, 35 Pads

7 digit2 color lighted LCD

with interactive word promptsMicrowave Cooking Cycles Cook Time Yes Auto Reheat (Sensor) Yes - 4 Categories Auto Defrost (Non-Sensored) Yes - 4 Categories By Weight Auto Cook (Sensor) Yes - 6 Categories Sensor One Touch Popcorn (Sensor One Touch) Yes Baked Potato (Sensor One Touch) Yes - 1-6 (Similar in Size) Fresh Vegetable (Sensor One Touch) Yes Sensor Reheat Yes Warm Hold Up to 30 Minutes Add a Minute YesConvection Cooking Cycles NoCombination Cooking Cycles NoCustom Help Features Child Lock Yes Audible Signal Elimination Yes Auto Start Yes Language/Weight Selection Yes Pause Door Open Clock YesIndependent Minute Timer: Yes Stage Cooking Yes (4) Demo Mode Yes More/Less Function Yes Sales Demonstration Mode Yes - Hidden Off/Cancel YesCook Power Yes Type Electronic Range 0% - 100% Scale Digital Levels Eleven Operation Direct EntryExhaust Fan NoCooktop Light YesSettings 1 level (High) High YesAccent Light Yes Low Yes Wattage 2 x 30 Watt Light Cover Glass Size 7" W x 2 3/4" DDisplay IndicatorsPower Failure Indication Yes - ':' Displayed Flashing w/On-Off Function No Independent Minute Timer Yes - 1 Long Beep

Display

1-11

MODEL KOMS155MBL / WH/BT/SSOVEN INTERIOR FEATURESCapacity 1.5 Cubic FeetFinish Painted AcrylicCooking Power 1100 Watts (IEC-705 Rating) Turntable YesGlass turntable diameter 14"Cooling Fan Automatic - On if oven is operating,

Off if door openRack No

Automatic - Turns on when ovendoor is open or oven is operating.

30 WattTurntable Roller YesTemp Probe NoDOOR FEATURESStamped Steel Yes - With Tempered CoverWindow GlassWindow Size 10 1/4" x 6"MICROWAVE SYSTEMDistribution Top Feed w/ StirrerMagnetron One standardSAFETY FEATURESInterlock Three Door/Latch Operated

Primary, secondary and monitorThermal Protectors Three - 1 Magnetron, 1 Oven Cavity, 1 HoodEXTERIOR FEATURESOutside Dimensions 23 7/8" W X 14 1/16" H X 15 9/16"DCabinet Finish Painted SmoothConstruction Unitized Chassis with

Wrapper & Mounting PlateBottom Finish Painted Steel - SmoothControl, Door and Grille Construction One Piece MoldedCooktop Light w/Touch Control 2 Lamps - 30 Watt Easy AccessPower Cord Length 3 FeetOTHER SPECIFICATIONS

120V, Single Phase, 60 Hz1530 Watts, For Use With

15 - 20 Amp CircuitDomestic Use Only YesAgency Approvals FCC, DHHS, U.L. Listed, CSAApprox. Shipping Weight - Lb 50Approx. Net Weight - Lb 46APPROVED ACCESSORIESExhaust Damper Assembly N / AHardware for Installation Yes (1 Set)LITERATUREUse & Care Guide YesCooking Guide YesInstallation Instructions YesWall Mounting Template YesCabinet Mounting Template YesWarranty In Use & Care GuideTech Sheet YesJob Aid 4317340

Electrical

Light

1-12

KITCHENAID MICROWAVE OVEN WARRANTY

LIMITED FOUR-YEAR WAR-RANTY Secondthrough fifth yearfrom Date ofPurchase.

ONE-YEAR FULLWARRANTYFrom Date ofPurchase.

LENGTH OFWARRANTY:

KITCHENAIDWILL PAY FOR:

KITCHENAIDWILL NOT PAY FOR:

Replacement partsand repair laborcosts to correctdefects in materi-als or workman-ship. Service mustbe provided by aKitchenAid-desig-nated servicingcompany.

Replacementmagnetron tube onmicrowave ovens ifdefective in materi-als or workman-ship.

A. Service calls to:

1. Correct the installation of the microwaveoven.

2. Instruct you how to use the microwaveoven.

3. Replace house fuses or correct housewiring.

4. Replace owner-accessible light bulbs.B. Repairs when microwave oven is used in

other than normal single-family householduse.

C. Pickup and delivery. The microwave is de-signed to be repaired in the home.

D. Damage to the microwave oven resultingfrom accident, alteration, misuse, abuse, fire,flood, acts of God, or use of products notapproved by KitchenAid.

E. Any labor costs during the limited warranty.

F. Repairs to parts or systems resulting fromunauthorized modifications made to theappliance.

G. Replacement parts or repair labor costs forunits operated outside the United States.

KITCHENAID OR KITCHENAID CANADA DO NOT ASSUME ANY RESPONSIBILITY FORINCIDENTAL OR CONSEQUENTIAL DAMAGES. Some states or provinces do not allow theexclusion or limitation of incidental or consequential damages, so this exclusion or limitation maynot apply to you. This warranty gives you special legal rights, and you may also have other rightswhich vary from state-to-state or province-to-province.

Outside the United States and Canada, a different warranty may apply. For details, pleasecontact your authorized KitchenAid dealer.

If you need service first see the “Troubleshooting” section of the Use and Care Guide. Afterchecking ”Troubleshooting,” additional help can be found by checking the “Assistance or Ser-vice” section, or by calling our Customer Interaction Center telephone numbers, listed below,from anywhere in the U.S.A. or Canada.

KitchenAid: 1-800-422-1230Canadian Residents call: 1-800-807-6777

2-1

INSTALLATION INFORMATIONREMOVING THE MICROWAVE OVEN

Excessive Weight Hazard

Use two or more people to move andinstall microwave oven.

Failure to do so can result in back orother injury.

WARNING

1. Open the cabinet doors and unplug thepower cord from the wall outlet.

2. Remove the two cabinet mounting screws.

3. Remove the two screws from the latchingarms.

4. While supporting the microwave oven,pull down on the two latching arms at thebottom of the oven to release them fromthe mounting panel hooks, and removethe oven from the wall.

ScrewScrew

Power Plug

LatchingArm

LatchingArm

Screw

Screw

Hook

2-2

— NOTES —

3-1

THEORY OF OPERATIONMICROWAVE OPERATING SEQUENCE

OFF CONDITION

Closing the door activates the secondary (doorsensing) interlock switch, and the primary in-terlock switch. The monitor switch contacts areopened.

When the oven is plugged in, 120 VAC issupplied to the control unit (see the illustrationbelow).

1. The display will show “WELCOME.” Toset any program or set the clock, you mustfirst touch the STOP/CLEAR keypad. Thedisplay will clear, and a colon ( : ) willappear.

POWER LEVEL (P-0 TO P-90)COOKING

When “Variable Cooking Power” is pro-grammed, 120 VAC is supplied to the powertransformer intermittently through the contactsof relay RY2, which is operated by the controlunit within an interval second time base.

VARI-MODE ON TIME OFF TIME

HIGH (100% power) 32 sec. 0 sec.

P-90 (90% power) 30 sec. 2 sec.

P-80 (80% power) 26 sec. 6 sec.

P-70 (70% power) 24 sec. 8 sec.

P-60 (60% power) 22 sec. 10 sec.

P-50 (50% power) 18 sec. 14 sec.

P-40 (40% power) 16 sec. 16 sec.

P-30 (30% power) 12sec. 20 sec.

P-20 (20% power) 8 sec. 24 sec.

P-10 (10% power) 6 sec. 26 sec.

P-0 (0% power) 0 sec. 32 sec.

NOTE: The ON/OFF time ratio does not corre-spond with the percentage of microwavepower, because approximately 3 seconds areneeded for heating of the magnetron filament.

Microwave power operation is as follows (theindicated power is approximate):

Oven Schematic-Off Condition

NOTE: " " indicates components with potential above 250V.

SCHEMATICNOTE: CONDITION OF OVEN1. DOOR CLOSED.2. CLOCK APPEARS ON DISPLAY.

MAGNETRON TEMPERATURE FUSE

FUSE 20A

TU

RN

TA

BLE

MO

TO

R

FA

NM

OT

OR

MA

GN

ET

RO

N

OV

EN

LA

MP

MO

NIT

OR

SW

ITC

H

BLK

WH

T

POWERTRANSFORMER

HIGH VOLTAGECAPACITOR1.0 F/ AC2300V

HIGH VOLTAGERECTIFIER

COM.N.O.

COM.

CONTROL UNIT

GND

GRN

A1

A3 A5 N.O.

B2

B1

DOORSENSINGSWITCH

PRIMARYINTERLOCKSWITCH

120 V AC.60 Hz

HOODLAMP

HL

RY1

RY2

SECONDARYINTERLOCK RELAY

OVEN LAMPRELAY

FMOL TTM

RY3

RY4

CAVITY TEMPERATURE FUSE

HL

F1

F2

F3 AH

SE

NS

OR

3-2

SENSOR COOKING CONDITION

Using the Sensor Cooking function, the foodsare cooked without figuring time, power level,or quantity. When the oven senses enoughsteam from the food, it relays the information toits microprocessor, which calculates the re-maining cooking time and power level neededfor best results.

When the food is cooked, water vapor is devel-oped. The sensor ”senses” the vapor, and itsresistance gradually increases. When the re-sistance reaches the value set according to themenu, supplementary cooking is started. Thetime of supplementary cooking is determinedby experimenting with each food category, andthen sent to the microcomputer for processing.

The following example shows how the sensorworks (baked potatoes):

1. When baked potatoes are at room tem-perature, and begin cooking, vapor isemitted very slowly. As the potatoes areheated, moisture and humidity are morerapidly emitted.

2. The sensor detects the moisture and hu-midity, and calculates the cooking time,and the variable power.

3-3

Oven Schematic-Cooking Condition

SCHEMATICNOTE: CONDITION OF OVEN1. DOOR CLOSED.2. COOKING TIME PROGRAMMED.3. VARIABLE COOKING CONTROL "HIGH".4. "START" BUTTON PRESSED.

TU

RN

TA

BLE

MO

TO

R

FA

NM

OT

OR

MA

GN

ET

RO

N

OV

EN

LA

MP

MO

NIT

OR

SW

ITC

H

POWERTRANSFORMER

HIGH VOLTAGERECTIFIER

COM.N.O.

COM.

CONTROL UNIT

N.O.

B2

B1

DOORSENSINGSWITCH

PRIMARYINTERLOCKSWITCH

RY1

RY2

SECONDARYINTERLOCK RELAY

OVEN LAMPRELAY

FMOL TTM

MAGNETRON TEMPERATURE FUSE

FUSE 20A

BLK

WH

T HIGH VOLTAGECAPACITOR1.0 F/ AC2300V

GND

GRN

A1

A3 A5

120 V AC.60 Hz

HOODLAMP

HL

RY3

RY4

CAVITY TEMPERATURE FUSE

HL

F1

F2

F3 AH

SE

NS

OR

Cooking Sequence

1. Operate the oven in the Sensor Cookingmode by referring to the Use and CareGuide that was supplied with the unit.

NOTE: The oven should not be operated onSensor Cooking immediately after connectingpower. Wait at least 2 minutes before usingthe Sensor Cooking.

2. The coil of shut-off relay RY1 is energized,(see the illustration below), the oven lamp,turntable and cooling fan motors are turnedon, but the power transformer is not turnedon.

3. After approximately 16 seconds, cook re-lay RY2 is energized. The power trans-former is turned on, microwave energy isproduced, and the first stage is started.

NOTE: The 16 seconds is the cooling timerequired to remove any vapor from theoven cavity and sensor. During this firststage, do not open the door, or touch theSTOP/CLEAR keypad.

4. When the sensor detects the vapor emit-ted from the food, the display switchesover to the remaining cooking time, andthe timer counts down to zero. At this time,the door may be opened to access thefood.

5. When the timer reaches zero, an audiblesignal sounds. The shutoff and cook re-lays are de-energized, and the power trans-former, oven lamp, etc., are turned off.

6. After opening the door, or touching theSTOP/CLEAR keypad, the time of day willreappear on the display, and the oven willrevert to an OFF condition.

3-4

THE ABSOLUTE HUMIDITY (AH) SENSOR CIRCUIT

ventilation opening for sensing Sensing part(Open vessel)

Sensing part(Closed vessel)

Thermistors

C

S

R3

R1

R2

+

Operationalamplifier

Outputvoltage

S : Thermistor open vesselC : Thermistor closed vessel

2Absolute humidity (g/m )

Out

put v

olta

ge

Absolute humidity vs,output voltage characteristic

SW1

SW2

SW3

SW4

SW5

P57

P56

P55

P51

P53

LSI(IC1)

AN0

AN1

620k

300k

150k

75k

37.4k

11

17

15

10

9

13

12

47k

47k

IC215k

0.01

uF

0.1u

F

0.01

uF

+

VA : -15V VA : -15V

R50

330

C50

C51

C51

C50

S

F-2 1.8k

F-1

F-3C

3.57k

3.32k

VC : -5V

0.1

uF

C. Thermistor in closed vesselS. Thermistor in open vessel

R53

R54

R52

R51

360kR54R53

R50 R51

D50

R55

R56

R57

R52

The illustration below shows the basic struc-ture of an absolute humidity sensor. A bridgecircuit is formed by two thermistors and tworesistors (R1 and R2).

The output of the bridge circuit is amplified bythe operational amplifier. Each thermistor issupplied with a current to keep it heated atabout 150°C (302°F). The resultant heat isdissipated in the air. If the two thermistors areplaced in different humidity conditions, theyshow different degrees of heat conductivityleading to a potential difference between them,causing an output voltage from the bridgecircuit. The intensity of the output voltage in-creases as the absolute humidity of the airincreases. Since the output is very minute, it isamplified by the operational amplifier.

The Absolute Humidity Sensor includes twothermistors, as shown in the illustration below.One thermistor is housed in the closed vesselfilled with dry air, while another in the openvessel. Each sensor is provided with the pro-tective cover made of metal mesh to protect itfrom the external airflow.

With this voltage given, switches SW1 to SW5in the LSI are turned on in such a way as tochange the resistance values in parallel withresistors R53 - R57. Changing the resistancevalues results in that there is the same poten-tial at both the F-3 terminal of the absolutehumidity sensor, and the AN0 terminal of theLSI. The voltage of AN1 terminal will indicateabout –2.5V. This initial balancing is set upabout 16 seconds after the unit is put in theSensor Cooking mode. As the sensor cookingproceeds, the food is heated to generate mois-ture. This unbalances the bridge circuit, andincreases the voltage available at the AN1terminal of the LSI.

The LSI observes the voltage at the AN1 termi-nal, and compares it with its initial value. Whenthe comparison rate reaches the preset value,(fixed for each menu to be cooked), the LSIcauses the unit to stop sensor cooking. There-after, the unit goes to the next operation auto-matically.

The LSI starts to detect the initial voltage at theAN1 terminal 16 seconds after the unit hasbeen put in the Sensor Cooking mode. If it is notpossible to balance the bridge circuit, due todisconnection of the absolute humidity sensor,“ERROR” will appear on the display, and thecooking will be stopped.

The detector circuit of the AH sensor is shownat the bottom of the next column. It is used todetect the output voltage of the absolute hu-midity circuit to allow the LSI to control thesensor cooking of the unit. When the unit is setin the Sensor Cooking mode, a 16-secondclearing cycle occurs, the detector circuit startsto function, and the LSI observes the initialvoltage available at its AN1 terminal.

4-1

COMPONENT LOCATIONS

This section instructs you on how to service each component inside the Over-The-CounterMicrowave Oven. The components and their locations are shown below.

COMPONENT ACCESS

CavityTemperatureFuse

HumiditySensor

MagnetronTemperatureFuse

Magnetron

Line Fuse

ControlBoard

Oven Lamp

Cooling Fan Motor

HV Diode

HV Capacitor

HV Transformer

Control Panel(Part Of Door)

TurntableMotor

Accent & Task Lamps

Primary,Monitor, &Secondary(Door Sensing)InterlockSwitches

4-2

REMOVING THE CABINET

1. Unplug microwave oven or disconnectpower.

2. Remove the microwave oven from itsmounting location (see page 2-1 for theprocedure).

3. Facing the front of the unit, remove the topscrew and three right side screws from thecabinet.





WARNING4. Facing the rear of the unit, remove the four

rear cabinet screws.

Top Screw 3 Side Screws

5. Pull the cabinet back and unhook the slotsfrom the chassis tabs at the top and sides.Pull the cabinet back far enough to accessthe power cord connector.

6. Unlock the power cord connector with ascrewdriver blade and disconnect it, thenremove the cabinet.

Rear Screw (1 of 4)

Screwdriver

Power CordConnector

4-3

REMOVING THE CONTROL BOARD





WARNING5. Disconnect the following connectors from

the control board:

a) 3-wire connector from CN-F.b) 2-wire connector from CN-B.c) 11-wire connector from CN-C.d) 5-wire connector (with red & red-brown

wires) from CN-A.

e) Connector with 2 gry & 2 wht wires atrelay RY1.

f) Connector with 2 blk & 2 red wires atrelay RY2.

Screw

6. Remove the screw from the control boardand unclip it from the decorative panel.

CN-C

4. Lift the panel and unhook the side tabs,then pull the panel forward as far as thewires will allow.

RY1

RY2

CN-A

CN-B

CN-F

Screw

LockingClip


2. Open the microwave oven door.

3. Remove the screw from the decorativepanel.

DecorativePanel

4-4

REMOVING THE DOOR INTERLOCK SWITCH ASSEMBLY



3. Remove the decorative panel and controlboard from the unit (see page 4-3 for theprocedure).

4. Push the secondary interlock actuator to-ward the right and remove the pin from thechassis hole, then carefully remove theother pin from its chassis hole, and re-move the actuator.





WARNING5. Remove the two mounting screws and

star washers from the door interlock switchbracket.

6. Unlatch the door interlock switch bracketand remove the switch assembly just farenough to disconnect the following wiresfrom the interlock switch terminals (seethe photo at the top of the next page):

a) Primary Interlock Switch: Red wire fromthe normally-closed (NC) terminal, andgreen wire from the normally-open (NO)terminal.

b) Monitor Interlock Switch: Red wire fromthe normally-closed (NC) terminal, andwhite wire from the normally-open (NO)terminal.

c) Secondary (Door Sensing) InterlockSwitch: Two white wires from the nor-mally-closed (NC) terminal, and graywire from the normally-open (NO) ter-minal.

RightActuator

Pin

Secondary Interlock Actuator

Screw & StarWasher

Screw & StarWasher

Door InterlockSwitch Bracket

Latching Arm

Latching Arm

4-5

7. Unlatch the interlock switch you are re-moving from the bracket and slide it off thealignment pin. Be careful not to break thelocking arm or the pin on the bracket.

PrimaryInterlockSwitch

MonitorInterlockSwitch

SecondaryInterlockSwitch

Red (NC)

Green (NO)

White (NO)

Red (NC)

Gray(NO)

2 White(NC)

PrimaryInterlockSwitch

MonitorInterlockSwitch

SecondaryInterlockSwitch

Press Down OnLocking Arm

Turn Switch On PinAnd Remove

Pin

REASSEMBLY NOTE: Reinstall the switchassembly bracket and then connect the wiresto the switch terminals. Use the photo to makesure of your connections.

4-6

REMOVING THE LINE FUSE AND OVEN LAMP



3. Remove the decorative panel and controlboard from the unit (see page 4-3 for theprocedure).





WARNING4. To remove the line fuse, unsnap it from

its holder.

Line Fuse

Oven Lamp

5. To remove the oven lamp:

a) Turn the lampholder counterclockwiseand remove it from the chassis.

b) Unscrew the lamp from the lampholder.

Line Fuse

Oven Lampholder

Oven Lamp

Remove

4-7

REMOVING AN ACCENT OR TASK LAMPHOLDER AND THE TURNTABLE MOTOR





WARNING

Screw (1 of 6)

Bottom Panel

3. To remove an accent or a tasklampholder:

a) Turn the lampholder counterclockwiseand unhook it from the mountingbracket.

b) Remove the bulb from the lampholder.

c) Cut the wires near the lampholder.

d) Splice the wires from the newlampholder to the wiring harness withtwo twist-on connectors.

Accent & Task Lampholders

Wiring Harness

4. To remove the turntable motor:

a) Disconnect the 2-wire connector fromthe motor terminals.

b) Remove the two screws and removethe motor from the bottom of the unit.

2-WireConnector

TurntableMotor

Remove

Screw (1 of 2)

(Viewed From Bottom Of Unit)

Bulb


2. Remove the six screws from the bottompanel and lower the panel as far as thewiring will allow.

4-8

REMOVING THE HUMIDITY SENSOR &CAVITY TEMPERATURE FUSE


2. Remove the cabinet from the microwaveoven (see page 4-2 for the procedure).

3. Remove the screw from the left top braceand remove the brace from the unit.





WARNING

4. To remove the humidity sensor:

a) Remove the decorative panel and tilt itforward (see page 4-3 for the proce-dure).

c) Remove the two screws and the greenground wire from the humidity sensorand remove the sensor.

Left Brace

Screw

Cavity Temp Fuse Humidity Sensor

b) Disconnect the 3-wire sensor connec-tor (red, black, & white wires) from thecontrol board at CN-F.


Connect green ground wire to groundscrew.


Humidity Sensor Connector (CN-F)

Humidity Sensor

Ground Wire

Screw (1 of 2)

4-9

5. To remove the cavity temperature fuse:

a) Remove the screw and unhook thefuse from the unit.

b) Disconnect the two wire connectorsfrom the fuse terminals.

REASSEMBLY NOTE: Reconnect the wires tothe cavity temperature fuse terminals beforemounting it to the unit.

Connector (1 of 2)Cavity Temperature Fuse

Screw

4-10

REMOVING THE MAGNETRON TEMPERATUREFUSE AND THE MAGNETRON







WARNING

5. To remove the magnetron temperaturefuse:

a) Disconnect the wire connectors fromthe fuse terminals.

b) Remove the screw from the fuse, un-hook it from the chassis, and remove it.

3. Discharge the high voltage capacitorterminals with a 20,000 Ω resistor tochassis ground.

Magnetron Temperature FuseMagnetron

4. Carefully lift the adhesive side of the foampad off the top of the chassis and removethe pad from the opening.

High Voltage Capacitor

Foam Pad

Magnetron Temperature Fuse

Wire Connectors Screw

4-11

6. To remove the magnetron:

a) Remove the screw from the oven lampshroud, unhook the locking arm, andposition the shroud so you can accessthe left magnetron screws.

b) Disconnect the two wire connectorsfrom the magnetron terminals.

c) Remove the one top and four sidescrews from the magnetron and re-move the magnetron from the unit.

Top Magnetron Screw

4 Magnetron Screws

Shroud Screw

Locking Arm

2 WireConnectors

OvenLampShroud

4-12

REMOVING THE HIGH VOLTAGE CAPACITOR & DIODE,AND THE COOLING FAN MOTOR







WARNING


4. Position the unit on its back panel.

5. Remove the six screws from the bottompanel and tilt the panel down as far as thewiring will allow.

6. Remove the bottom screw from the mount-ing bracket for the high voltage capacitorand diode, and the cooling fan motor.

Screw (1 of 6)

Bottom Panel

7. Close the bottom panel and hold it closed,then position the unit to its upright positionso the right side faces you, as shown in thephoto to the left.

High Voltage Capacitor & Diode& Cooling Fan Motor

Bottom Bracket Screw

Foam Pad


4-13

8. Carefully lift the left side of the foam pad atthe top of the chassis, and fold it backunder the right chassis bracket.

9. Remove the screw from the top of the highvoltage capacitor and cooling fan motormounting bracket.

Right ChassisBracket

Bracket TopScrew

Foam Pad

10. Disconnect the three wire connectors fromthe high voltage capacitor terminals.

12. To remove the high voltage capacitor,remove the mounting screw from the ca-pacitor bracket, and remove the capacitor.

13. To remove the high voltage diode:

a) Remove the mounting screw from thecapacitor bracket.

b) Disconnect the diode wire from themagnetron terminal and remove thediode.

11. Unhook the top and bottom of the mount-ing bracket for the high voltage capacitor& diode, and the cooling fan motor fromthe unit, and pull it out just far enough toaccess the capacitor bracket mountingscrew.

High Voltage Capacitor Wires

To HV Transformer

To Magnetron

High Voltage Diode

Capacitor Bracket Screw

High Voltage Capacitor

High VoltageDiode Wire (OnMagnetron)

Continued on the next page.

4-14

14. To remove the cooling fan motor:

a) Disconnect the 2-wire connector fromthe motor terminals.

b) Pull the fan blade off the motor shaft.

c) Remove the two screws from the motorand remove it from the bracket.

2-Wire Connector

Cooling Fan Motor

Fan Blade

Fan MotorScrews

4-15

REMOVING THE HIGH VOLTAGE TRANSFORMER







WARNING


High Voltage Transformer High Voltage Capacitor

4. Disconnect the three wires from the highvoltage transformer terminals (see thephoto at the top of the right column).

5. Disconnect the high voltage transformerwires from the magnetron and the highvoltage capacitor terminals.

6. Position the unit on its back panel.

7. Remove the six screws from the bottompanel and tilt the panel down as far as thewiring will allow.

8. Hold the high voltage transformer in place,and remove the two screws from the bot-tom of the transformer.

High Voltage Transformer Connections

9. Position the unit to its upright position andslide the transformer out of the unit.

High Voltage Transformer

Screw (1 of 6)

Bottom Panel

2 HV Transformer Screws


4-16

REMOVING THE OVEN DOOR ASSEMBLY



3. Remove the decorative panel and tilt itforward (see page 4-3 for the procedure).

4. Disconnect the control panel’s 11-wireconnector from the control board at con-nector CN-C.





WARNING

11-WireConnectorAt CN-C

5. Remove the screw from each end of thefront trim.

6. Lay the unit on its back panel.

7. Slide the front trim to the left and unhookit from the chassis, then lift the trim off theunit, and unhook the control panel cablefrom its clips.

8. Cut the cable ties from the control panelcable, and pull the connector end of thecable out of the unit.

Front TrimScrews

Front Trim

Front TrimControl Panel Cable

4-17

9. Position the unit in its upright position.

10. Open the oven door.

11. Use a small-bladed screwdriver and prythe hinge covers out of the door.

Pry OutTop HingeCover

Pry OutBottom HingeCover

12. Lift the door so that the top and bottompins are out of the hinge holes, and re-move the door and control panel.

Remove Pin From Hinge

Remove Pin From Hinge

4-18

REMOVING THE OVEN DOOR & CONTROL PANELAND THE DISPLAY ASSEMBLY



3. Open the microwave oven door as far asit will go.





WARNING4. Use a putty knife and pry along the bottom

outer edge of the door choke to releasethe clips from the tabs. Carefully pull outon the choke as you release the tabs.Work counterclockwise around the chokeuntil you are able to remove it.

Outer Door Panel

Choke

Inner Door Panel

Door Latch Arms

Choke

Putty Knife

5. Lift the door latch arms and unhook themfrom the door panel, then pull out andremove the ends of the spring from thelatch arms and the panel.

Door Latch Spring

Door Latch Arms

4-19

9. Lay the outer door panel on a paddedsurface.

10. Remove the two screws from the displayassembly cover, then lift the cover at thescrew hole side, slide the opposite edgeout from under the tabs, and remove thecover.

REASSEMBLY NOTE: When mounting theassembly to the outer door panel, make surethat the notches in the color mask remainaligned with the board holder pins, (left photo).When you install the new display assembly, besure to keep the display glass and color inserttogether (right photo), so the mask does notbecome misaligned.

Display GlassIn Place

Color Mask AlignedWith Pins

6. Remove the four screws (2 at the top, and2 at the bottom) from the inner door panel.

7. Start at the bottom, and press to releasethe locking tabs along the inner door panelwhile you pull out on the panel. Continuearound the door in a counterclockwisedirection until you are able to remove thepanel from the outer door panel.

8. Lift the inner door panel off the hinges andremove it.

Top Inner Door Panel Screws

Bottom Inner Door Panel Screws

11. Use a small-bladed screwdriver and prythe 11-wire display connector away fromthe board connector.

12. Pull out on the locking ring and release theribbon cable, then pull the cable out of theconnector.

13. Remove the display assembly from theouter door panel.

Display Cover Screws

Display Cover Tabs

Display Connector

Ribbon Cable Locking Ring

Color Mask

4-20

— NOTES —

5-1

WARNINGElectrical Shock Hazard


Replace all parts and panels before operating.

Failure to do so can result in death or electrical shock.

Refer to page 4-4 for the procedure for servic-ing the door switches.


2. Disconnect the wires from the switch ter-minals.

COMPONENT TESTING

DOOR SWITCHES

Normally-Open

Normally-Closed

Before testing a component, be sure to ob-serve the following conditions:

• Discharge the high voltage capacitor beforeconducting any of the following tests.

• All operational checks using microwave en-ergy must be done with the microwave ovenloaded with a minimum of 275 ml (9.3 oz.) ofwater in a microwave safe container.

• Conduct a microwave energy test after per-forming any tests or repairs to the micro-wave.

• Check that all wire leads are in the correctposition before operating the microwaveoven.

• Grasp wire connectors when removing thewire leads from microwave parts.

3. Set the ohmmeter to the R x 1 scale.

4. Touch the ohmmeter test leads to theterminals of the primary or secondary

interlock switch (normally-open). Themeter should indicate an open circuit (in-finite).

5. Touch the ohmmeter test leads to theterminals of the monitor switch (normally-closed). The meter should indicate a closedcircuit (0 Ω).

NOTE: Pressing the actuator button shouldresult in opposite readings (normally-openshould read closed, and normally-closed shouldread open).

5-2

Refer to page 4-7 for the procedure for servicingthe turntable motor.


2. Disconnect the wire connector from theturntable motor.

3. Set the ohmmeter to the R x 1K scale.

4. Touch the ohmmeter test leads to theturntable motor terminals. The metershould indicate between 2700 and3800 Ω.

Refer to page 4-12 for the procedure for servic-ing the high voltage capacitor.



3. Disconnect the wires from the capacitorterminals.


5. Touch one of the ohmmeter test leads tothe chassis, and the other test lead to eachof the capacitor terminals. The metershould briefly indicate a low resistance,and then gradually return towards infinity.





TURNTABLE MOTOR HV CAPACITOR

5-3

HUMIDITY SENSOR

Refer to pages 4-8 and 4-10 for the proceduresfor servicing the cavity and magnetron tem-perature fuses.



3. Disconnect the wires from the terminals.


5. Touch the ohmmeter test leads to theterminals. The meter should indicate aclosed circuit (0 Ω).

NOTE: The cavity temperature fuse opens @329°F / 165°C. The magnetron temperaturefuse opens @ 257°F / 125°C. If the fuse isdefective, the ohmmeter will indicate an infinitecircuit.





Refer to page 4-8 for the procedure for servic-ing the humidity sensor.


2. Disconnect the 3-wire connector from thecontrol board.


4. Touch the ohmmeter test leads to theindicated wire terminals of the 3-wire con-nector. The meter should indicate as fol-lows:

Black to white = approximately 2800 Ω@ 77˚F/25˚C.

White to red = approximately 2800 Ω@ 77˚F/25˚C.

CAVITY & MAGNETRONTEMPERATURE FUSES

MagnetronTemperature Fuse

CavityTemperature Fuse

5-4





LINE FUSE

Refer to page 4-6 for the procedure for servic-ing the line fuse.



3. Touch the ohmmeter test leads to theends of the fuse. The meter should indi-cate a closed circuit (0 Ω).

Refer to page 4-12 for the procedure for servic-ing the cooling fan motor.



3. Touch the ohmmeter test leads to thecooling fan motor terminals. The metershould indicate between 60 and 80 Ω.

COOLING FAN MOTOR

5-5

Refer to page 4-12 for the procedure for servic-ing the high voltage diode.



3. Disconnect the diode wire connector fromthe filament terminal on the magnetron.


5. Touch the black (–) ohmmeter test lead tothe ground screw and the red (+) test leadto the lead end of the diode. The metershould indicate approximately 40 KΩ.

6. Reverse the ohmmeter test leads, and themeter should indicate infinity (∞).





HIGH VOLTAGE DIODEHIGH VOLTAGE TRANSFORMER

Filament Terminals

Refer to page 4-15 for the procedure for servic-ing the high voltage transformer.



3. Disconnect the filament wires, and thewires from the primary and secondaryterminals.


5. Touch the ohmmeter test leads to theprimary terminals. The meter should indi-cate less than 1 Ω.

6. Touch the ohmmeter test leads to thefilament terminals. The meter should indi-cate less than 1 Ω.

7. Touch one ohmmeter test lead to thesecondary terminal and the other test leadto the chassis. The meter should indicatebetween 60 and 80 Ω.

– +

SecondaryTerminal

Primary Terminals

–

+

5-6

Refer to page 4-10 for the procedure for servic-ing the magnetron.



3. Disconnect the wire connectors from thefilament terminals.


5. Touch the ohmmeter test leads to thefilament terminals. The meter should indi-cate less than 1 Ω.

6. Touch one ohmmeter test lead to thechassis, and the other test lead to each ofthe filament terminals. The meter shouldindicate infinity (∞).





MAGNETRON

Filament Terminals

6-1

DIAGNOSIS & TROUBLESHOOTING

IMPORTANT: If the oven becomes inopera-tive because of a blown monitor fuse, check themonitor switch, relay RY1, secondary interlockrelay RY2, secondary (door sensing) interlockswitch, and primary interlock switch beforereplacing the monitor fuse. If monitor fuse isreplaced, the monitor switch must also bereplaced. Use part #FFS-BA016/KiT as anassembly.

Whenever troubleshooting is performed withthe power supply cord disconnected, it may insome cases be necessary to connect the powersupply cord after the cabinet has been re-moved:

1. Disconnect the power supply cord, andthen remove the cabinet (see page 4-2).

2. Open the oven door and block it open.

3. Use a 20,000 Ω, 2-Watt resistor to ground,and discharge the high voltage capacitor.

4. Disconnect the leads to the primary of thepower transformer.

5. Ensure that the leads remain isolated fromother components and oven chassis byusing insulation tape.

6. After that procedure, reconnect the powersupply cord.

When the testing is completed:

1. Disconnect the power supply cord, andthen remove the cabinet (see page 4-2).

2. Open the door.

3. Use a 20,000 Ω, 2-Watt resistor to ground,and discharge the high voltage capacitor.

4. Reconnect the leads to the primary of thepower transformer.

5. Reinstall the cabinet.

6. Reconnect the power supply cord.

7. Run the oven and check all of the functions.

TROUBLESHOOTING

6-2

TOUCH CONTROL PANEL ASSEMBLY TESTThe touch control panel consists of semicon-ductor circuits. Unlike conventional microwaveovens, proper maintenance cannot be per-formed with only a voltmeter and ohmmeter.The touch control panel assembly is dividedinto the “Control Unit” and the “Key Unit.”

BEFORE TESTING

1. Disconnect the power supply cord.

2. Remove the cabinet (see page 4-2).

3. Open the door and block it open.

4. To discharge the high voltage capacitor,wait for 60 seconds.

5. Disconnect the leads to the primary of thehigh voltage transformer. Ensure that theseleads remain isolated from other compo-nents and oven chassis by taping themusing insulation tape.

Key Unit

1. Check key unit ribbon connection beforereplacement.


3. Reconnect the power supply cord after thecabinet is installed.

4. Run the oven and check all functions.The following symptoms indicate a defec-tive key unit.

a) When touching the pads, a certain padproduces no signal at all.

b) When touching a number pad, two fig-ures or more are displayed.

c) When touching the pads, sometimes apad produces no signal. If the key unitis defective, replace the key unit.

Control Unit

The following symptoms indicate a defectivecontrol unit. Before replacing the control unit,perform the “Key Unit” test to determine if thecontrol unit is faulty.

1. In connection with pads:

a) When touching the pads, a certaingroup of pads do not produce a signal.

b) When touching the pads, no pads pro-duce a signal.

2. In connection with indicators:

a) At a certain digit, all or some segmentsdo not light up.

b) At a certain digit, brightness is low.

c) Only one indicator does not light.

d) The corresponding segments of all dig-its do not light up; or they continue tolight up.

e) A wrong figure appears.

f) A certain group of indicators do not lightup.

9) The figure of all digits flicker.

3. Other possible problems caused by defec-tive control unit:

a) Buzzer does not sound or continues tosound.

b) Clock does not operate properly.

c) Cooking is not possible.

WHEN TESTING IS COMPLETED




4. Reconnect all leads removed from compo-nents during testing.


6. Reconnect the power supply cord after thecabinet is installed.

7. Run the oven and check all functions.

6-3




4. If the display fails to clear when the STOP/CLEAR keypad is depressed, first verify theflat ribbon cable is making good contact,and that the secondary (door sensing) in-terlock switch operates properly. The con-tacts should be closed when the door isclosed, and open when the door is open.

5. If the door sensing switch is good, discon-nect the flat ribbon cable that connects thekey unit to the control unit, and make surethe secondary (door sensing) interlockswitch is closed (either close the door orshort the door sensing switch connecter).

Use the Key Unit matrix, shown below, andplace a jumper wire between the pins thatcorrespond to the STOP/CLEAR keypadmaking momentary contact.

If the control unit responds by clearing witha beep, the key unit is faulty, and must bereplaced. If the control unit does not re-spond, it is faulty, and must be replaced. Ifa specific pad does not respond, the abovemethod may be used, after clearing thecontrol unit to determine if the control unit,or a keypad is at fault.




9. Run the oven and check all the functions.

G11

G12

G 9

G 8

POPCORN

BEVERAGE

SENSORREHEAT

CUSTOMHELP

FRESHVEGETABLES

POWERLEVEL

BAKEDPOTATOES

FRESHROLLS /

MUFFINS

FROZENROLLS /

MUFFINS

SENSORCOOK

CENTER

KEEPWARMPLUS

TIMERCLOCK

HOTWATER

DEFROSTCENTER

TASKLIGHT

ACCENTLIGHT

3

8

2

7

1

6

5

0

4

9

G 7 G 6 G 5 G 4 G 3 G 2 G 1

G10 STOPCLEAR

STARTMINUTE PLUS

KEY UNIT TEST

6-4


2. Remove the unit from the wall (see page2-1).




6. Disconnect the leads to the primary of thepower transformer. Ensure that these leadsremain isolated from other components andoven chassis by taping them using insula-tion tape.


8. Check the voltage between the normally-open terminal of relay RY2, and the nor-mally-open terminal of relay RY1 on thecontrol unit with an AC voltmeter. The metershould indicate 120 volts. If not, check theoven circuit.

RY1, RY2, RY3 & RY4 RELAYS

These relays are operated by DC voltage.

Check the voltage at the relay coil with a DCvoltmeter during the microwave cooking op-eration.

If a DC voltage is indicated, the relay is defec-tive. If a DC voltage is not indicated, check thediode that is connected to the relay coil. If thediode is good, the control unit is defective.


2. Open the oven door and block it.


4. Reconnect all of the leads that were re-moved from components during testing.



7. Run the oven and check all the functions.

RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS

RY1 Approx. -26.3V D.C. Oven lamp / Fan motor / Turntable motor

RY2(COOK) Approx. -25.3V D.C. Power transformer

RY3 Approx. -26.3V D.C. Hood lamp

RY4 Approx. -26.3V D.C. Hood lamp

RELAY TEST

6-5

Menu 1ST STAGE 2ND STAGESteaks/Chops LEVEL TIME LEVEL TIME

0.5lbs 60% 57sec. 40% 17sec.

DEFROST CENTER TEST1. Open the oven door.

2. Place one cup of water in the center of theturntable tray in the oven cavity.

3. Close the oven door.

4. Touch the “DEFROST CENTER” keypad.

5. Touch the number 2 keypad and the num-ber 5 keypad.

6. Touch the START keypad. The oven is nowin the Defrost Center cooking mode.

7. The oven will operate as follows:

8. If the operation is not correct, the controlunit is probably defective.

6-6

ABSOLUTE HUMIDITY (AH) SENSOR

WATER LOAD COOKING TEST

IMPORTANT: The oven should be fully as-sembled before performing the test procedure.

1. Make sure the oven has been plugged in atleast two minutes before checking sensorcook operation.

2. The cabinet should be installed and screwstightened.

3. Fill approximately 200 milliliters (7.2 oz) oftap water in a 1000 milliliter measuring cup.

4. Place the container on the center of tray inthe oven cavity.

5. Close the oven door.

6. Touch the TIMER/CLOCK keypad once,the POWER LEVEL keypad twice, theSTART keypad once, the number keypad 1once, and the number keypad 4 once. Theoven is now in the “Sensor Cooking” mode,and “AH20,” “SENSOR,” and “COOK” willappear in the display.

7. The oven will operate for the first 16 sec-onds without generating microwave en-ergy.

NOTE: “ERROR” will appear if the door isopened, or if the STOP/CLEAR keypad istouched during the first stage of sensor cook-ing.

8. After approximately 16 seconds, microwaveenergy is produced. If “ERROR” is dis-played, or if the oven does not turn off,replace the AH sensor, or check the controlunit (refer to the explanation on the nextpage).

If the oven stops after 5 minutes, and“ERROR” is displayed, the AH sensor isnormal. Check other parts except the AHsensor.

CHECKING THE INITIALSENSOR COOKING CONDITION

IMPORTANT: The oven should be fully as-sembled before performing the test procedure.

1. The oven should be plugged in at least twominutes before sensor cooking.

2. Room temperature should not exceed 95°F(35°C).

3. The unit should not be installed in any areawhere heat and steam are generated. Theunit should not be installed, for example,next to a conventional surface unit.

4. Exhaust vents are provided on the back ofthe unit for proper cooling and air flow in thecavity. To permit adequate ventilation, besure to install so as not to block these vents.There should be some space for air circula-tion.

5. Be sure the exterior of the cooking con-tainer and the interior of the oven are dry.Wipe off any moisture with a dry cloth, or apaper towel.

6. The Sensor works with food at normal stor-age temperature. For example, chickenpieces would be at refrigerator tempera-ture, and canned soup at room tempera-ture.

7. Avoid using aerosol sprays or cleaningsolvents near the oven while using Sensorsettings. The sensor will detect the vaporgiven off by the spray and turn off beforefood is properly cooked.

8. If the sensor has not detected the vapor ofthe food, “ERROR” will appear, and theoven will shut off.

6-7

TESTING THE AH SENSORAND/OR CONTROL UNIT

NOTE: To determine if the sensor is defective,the simplest method is to replace it with a newreplacement sensor.





5. Remove the AH sensor.

6. Install the new AH sensor.




10.Reconnect the oven to the power supplyand check the sensor cook operation asfollows:

a) Fill approximately 200 milliliters (7.2 oz)of tap water in a 1000 milliliter measur-ing cup.

b) Place the container on the center of trayin the oven cavity, and close the door.

c) Touch the TIMER/CLOCK keypad once,the POWER LEVEL keypad twice, theSTART pad once, the number pad 1once, and the number pad 4 once.

d) The control panel is in the “AutomaticSensor” mode.

e) The oven should turn off automatically,and the time for detecting moistureshould be displayed.

If the new sensor does not operate properly,the problem is with the control unit (refer to thefollowing section).

CHECKING THE CONTROL UNIT





5. Disconnect the sensor connector from thecontrol panel.

6. Connect the dummy resistor circuit (see theillustration on the next page) to the sensorconnector of the control panel.

7. Disconnect the leads to the primary of thepower transformer. Ensure that these leadsremain isolated from other components andoven chassis by taping them using insula-tion tape.

8. Reinstall the cabinet and reconnect thepower supply cord.

9. Check the sensor cook operation as fol-lows:

a) Touch the TIMER/CLOCK keypad once,the POWER LEVEL keypad twice, theSTART keypad once, the number 1 key-pad once, and the number 4 keypadonce.

b) The control panel is in the “SensorCooking” mode.

c) After approximately 19 seconds, pushthe plunger of the select switch for morethan 3 seconds. This condition is sameas for the AH sensor.

d) After approximately 3 seconds, the dis-play shows “X X . X X” (the time for de-tecting moisture). If the display is incor-rect, the control unit is probably defec-tive. If the display is correct, the AH sen-sor is probably defective.

Continued on the next page.

6-8

R1, R2 : 22 1% 1/2WR3 : 4.3k 5% 1/4WR4 : 1M 5% 1/4W

Plunger

NC

NO

COM

COM NO

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R1

R2

1

2

3

F-1

F-2

F-3

To connector (F)on Control Unit.

CONNECTOR

10.Disconnect the power supply cord.

11.Remove the cabinet.

12.Open the door and block it open.

13.To discharge high voltage capacitor, waitfor 60 seconds.

14.Disconnect the dummy resistor circuit fromthe sensor connector of control panel.

15.Perform the necessary repairs.

16.Reconnect all of the leads that were re-moved from components during testing andrepairing.

17.Reinstall the cabinet.

18.Reconnect the power supply cord.

19.Run the oven and check all of the functions.

20.Repeat the “Water Load Cooking Test” onpage 6-6, and make sure that the unitoperates properly.

Sensor Dummy Resistor Circuit

7-1

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SCHEMATIC DIAGRAM

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PRODUCT SPECIFICATIONS

AND

WARRANTY INFORMATION SOURCES

IN THE UNITED STATES:

FOR PRODUCT SPECIFICATIONS AND WARRANTY INFORMATION CALL:

FOR TECHNICAL ASSISTANCE WHILE AT THE CUSTOMER’S HOME CALL:

THE TECHNICAL ASSISTANCE LINE: 1-800-253-2870

HAVE YOUR STORE NUMBER READY TO IDENTIFY YOU AS AN

AUTHORIZED SERVICER

FOR LITERATURE ORDERS:

PHONE: 1-800-851-4605

IN CANADA:

FOR PRODUCT SPECIFICATIONS AND WARRANTY INFORMATION CALL:

1-800-461-5681

FOR TECHNICAL ASSISTANCE WHILE AT THE CUSTOMER’S HOME CALL:

THE TECHNICAL ASSISTANCE LINE: 1-800-488-4791

HAVE YOUR STORE NUMBER READY TO IDENTIFY YOU AS AN

AUTHORIZED SERVICER

FOR WHIRLPOOL PRODUCTS: 1-800-253-1301

FOR KITCHENAID PRODUCTS: 1-800-422-1230

FOR ROPER PRODUCTS: 1-800-447-6737

Documents

4317340 KAC-36 KitchenAid Over-The-Counter Microwave Oven