Sharp R-501FK User manual

R-501FK
R-501FW
Intheinterestofuser-safetytheovenshouldberestoredtoitsoriginal
condition and only parts identical to those specified should be used.
WARNING TO SERVICE PERSONNEL: Microwave ovens con-
tain circuitry capable of producing very high voltage and
current, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Recti-
fier Assembly, High Voltage Harness etc..)
TABLEOFCONTENTS Page
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY.................. INSIDE FRONT COVER
BEFORE SERVICING..................................................................................................... INSIDE FRONT COVER
WARNING TO SERVICE PERSONNEL .............................................................................................................. 1
MICROWAVE MEASUREMENT PROCEDURE .................................................................................................. 2
FOREWORD AND WARNING............................................................................................................................. 3
PRODUCT SPECIFICATIONS............................................................................................................................. 4
GENERAL INFORMATION ................................................................................................................................. 4
OPERATION ........................................................................................................................................................ 6
TROUBLESHOOTING GUIDE............................................................................................................................. 9
TEST PROCEDURE ...........................................................................................................................................10
TOUCH CONTROL PANEL ................................................................................................................................18
COMPONENTREPLACEMENTANDADJUSTMENTPROCEDURE ..................................................................23
PICTORIALDIAGRAM ........................................................................................................................................30
POWERUNITCIRCUIT.......................................................................................................................................31
CPUUNITCIRCUIT.............................................................................................................................................32
PRINTEDWIRINGBOARD .................................................................................................................................33
PARTS LIST........................................................................................................................................................34
PACKINGANDACCESSORIES .........................................................................................................................38
S62M188R501FE
R-501FK
R-501FW
MICROWAVEOVEN
MODELS
SERVICE MANUAL
SHARP ELECTRONCS CORPORATION This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
Service Headquarters: Sharp Plaza, Mahwah, New Jersey, 07430-2135
R-501FW

R-501FK
R-501FW
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROWAVE
ENERGY
(a) Do notoperate or allow the oven to be operated with the door open.
(b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other
microwavesource,andmake repairs as necessary: (1) interlock operation,(2)properdoor closing, (3)
sealandsealingsurfaces (arcing, wear, and other damage),(4)damageto or loosening of hinges and
latches,(5) evidence of dropping orabuse.
(c) Before turningon microwave powerfor any servicetest or inspectionwithin the microwavegenerating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment,
integrity,and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation
and transmission systems shall be repaired, replaced, or adjusted by procedures described in this
manualbefore the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be
performedoneachovenpriorto release to the owner.
BEFORE SERVICING
Before servicing an operative unit, perform a microwave emission check as per the
Microwave Measurement Procedure outlined in this service manual.
If microwave emissions level is in excess of the specified limit, contact SHARP
ELECTRONICSCORPORATIONimmediately @1-800-237-4277.
If the unit operates with the door open, service person should 1) tell the user
not to operate the oven and 2) contact SHARP ELECTRONICS CORPORATION and Food and
Drug Administration's Center for Devices and Radiological Health immediately.
Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit
found with emissions in excess of 4mW/cm2. The owner of the unit should be instructed
not to use the unit until the oven has been brought into compliance.

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WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of pro-
ducing very high voltage and current, contact with
following parts
may result in a severe, possibly
fatal, electrical shock.
(Example)
HighVoltageCapacitor,HighVoltagePowerTrans-
former,Magnetron,HighVoltageRectifierAssem-
bly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
Before Servicing
1. Disconnect the power supply cord , and then
remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
WARNING:RISK OF ELECTRIC SHOCK.
DISCHARGE THE HIGH-VOLTAGE
CAPACITOR BEFORE SERVICING.
The high-voltage capacitor remains charged about 60
secondsaftertheovenhasbeenswitchedoff.Waitfor60
secondsandthenshort-circuittheconnectionofthehigh-
voltagecapacitor(thatistheconnectingleadofthehigh-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Whenever troubleshooting is performed the power supply
mustbedisconnected.Itmay,in somecases,benecessary
to connect the power supply after the outer case has been
removed, in this event:
1. Disconnect the power supply cord, and then remove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power
transformer.
5. Ensure that the leads remain isolated from other
components and oven chassis by using insulation tape.
6. After that procedure, reconnect the power supply cord.
When the testing is completed,
1. Disconnect the power supply cord, and then remove
outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Reconnect the leads to the primary of the power
transformer.
5. Reinstall the outer case (cabinet).
6. Reconnectthepower supply cord after theouter case is
installed.
7. Run the oven and check all functions.
After repairing
1. Reconnect all leads removed from components during
testing.
2. Reinstall the outer case (cabinet).
3. Reconnectthepower supply cord after theouter case is
installed.
4. Run the oven and check all functions.
Microwaveovensshouldnotbeoperatedempty.To testfor
the presence of microwave energy within a cavity, place a
cup of cold water on the oven turntable, close the door and
set the power to HIGH and set the microwave timer for two
(2) minutes. When the two minutes has elapsed (timer at
zero) carefully check that the water is now hot. If the water
remainscoldcarryoutBeforeServicing procedureandre-
examine the connections to the component being tested.
When all service work is completed and the oven is fully
assembled,themicrowavepoweroutputshouldbechecked
and a microwave leakage test should be carried out.
Don't Touch !
Danger High Voltag
e

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MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
shouldnotexceed1mW/cm2atanypoint5cmormorefromtheexternalsurfaceoftheoven,measuredpriortoacquisition
byapurchaser,andthereafter(throughthe useful lifeoftheoven),5mW/cm2atanypoint5cmormore from theexternal
surface of the oven.
2) Safety interlock switches:
Primary interlock relay switch shall prevent microwave radiation emission in excess of the requirement as above
mentioned. Secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of
5 mW/cm2 at any point 5cm or more from the external surface of the oven.
B.Preparationfortesting:
Beforebeginning theactual measurementofleakage,proceedasfollows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard for
microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5O C (68OF) in the center of the oven cavity.
Thewatercontainershallbe alowformof600ml(20oz) beakerwithaninsidediameterofapprox.8.5 cm(3-1/2in.)and
made of an electrically nonconductive material such as glass or plastic.
Theplacing of this standardload in the ovenis important notonly to protect theoven, but also toinsure that any leakage
is measured accurately.
4) Set the cooking control on Full Power Cooking Mode.
5) Closethedoorandselectacookcycleofseveralminutes.Ifthewaterbeginstoboilbeforethesurveyiscompleted,replace
it with 275 ml of cool water.
C. Leakage test:
Closed-door leakage test (microwave measurement):
1) Grasptheprobeofthesurveyinstrumentandholditperpendiculartothegapbetweenthedoorandthebodyoftheoven.
2) Movetheprobeslowly,notfasterthan1in./sec.(2.5cm/sec.)alongthegap,watchingforthemaximumindicationonthe
meter.
3) Checkforleakageatthedoorscreen,sheetmetalseamsandotheraccessiblepositionswherethecontinuityofthemetal
has been breached (eg., around the switches, indicator, and vents).
Whiletestingforleakagearoundthedoor,pullthedoorawayfromthefrontoftheovenasfarasispermittedbytheclosed
latch assembly.
4) Measurecarefullyatthepointofhighestleakageandmakesurethatthehighestleakageisnogreaterthan4mW/cm2,and
that the primary interlock switch/secondary interlock relay does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.

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SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
MICROWAVE OVEN
R-501FK/R-501FW
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
ServicePersonnelwithOperationandServiceInformationfortheSHARP
MICROWAVEOVENS,R-501FK,R-501FW.
It is recommended that service personnel carefully study the entire text
ofthismanualsothattheywillbequalifiedtorendersatisfactorycustomer
service.
Checktheinterlockswitchesandthedoorsealcarefully.Specialattention
shouldbegiventoavoidelectricalshockandmicrowaveradiationhazard.
WARNING
Never operate the oven until the following points are ensured:
(A) The door is tightly closed.
(B) The door brackets and hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is no other visible damage with the oven.
Servicing and repair work must be carried out only by trained service
personnel. DANGER
Certain initial parts are intentionally not grounded and present
ariskof electricalshockonly duringservicing.Serviceperson-
nel - Do not contact the following parts while the appliance is
energized;
High Voltage Capacitor, Power Transformer, Magnetron, High
Voltage Rectifier Assembly, High Voltage Harness;
If provided, Vent Hood, Fan assembly, Cooling Fan Motor.
All the parts marked “*” on parts list are used at voltages more than
250V.
Removal of the outer wrap gives access to voltage above 250V.
All the parts marked “∆” on parts list may cause undue microwave
exposure, by themselves, or when they are damaged, loosened or
removed.
PRODUCTDESCRIPTION
GENERALINFORMATION
OPERATION
TROUBLESHOOTINGGUIDEAND
TESTPROCEDURE
TOUCHCONTROLPANEL
COMPONENTREPLACEMENT
ANDADJUSTMENTPROCEDURE
WIRINGDIAGRAM
PARTS LIST

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GENERAL INFORMATION
GROUNDING INSTRUCTIONS
This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed
and grounded in accordance with the National Electrical Code and local codes and ordinances.
Intheeventofanelectricalshortcircuit,groundingreducestheriskofelectricshockbyprovidinganescapewirefortheelectric
current.
WARNING: Improper use of the grounding plug can result in a risk of electric shock.
ElectricalRequirements
The electrical requirements are a 120 volt 60 Hz, AC only,
15or20amp.fusedelectricalsupply.Itisrecommendedthataseparatecircuitservingonlythisappliancebeprovided.When
installing this appliance, observe all applicable codes and ordinances.
A short power-supply cord is provided to reduce risks of becoming entangled in or tripping over a longer cord.
Whereatwo-prongedwall-receptacleisencountered,itisthepersonalresponsibilityandobligationofthecustomertocontact
SPECIFICATION
ITEM DESCRIPTION
PowerRequirements 120 Volts
13.0Amperes,1550 watts
60Hertz
Singlephase,3wiregrounded
PowerOutput 1000watts(IEC705TESTPROCEDURE)
Operatingfrequencyof2450MHz
CaseDimensions Width 24"
Height 13-3/8"
Depth 19-1/8"
CookingCavityDimensions Width 17-3/8"
Height 10-1/2"
2.0 Cubic Feet Depth 18-5/8"
ControlComplement Touch Control System
Clock ( 1:00 - 12:59 )
Timer (0 - 99 min. 99 seconds)
MicrowavePowerforVariableCooking
Repetition Rate;
P-HI .................................................. Fullpowerthroughout thecookingtime
P-90 ....................................................................approx. 90% of Full Power
P-80 ....................................................................approx. 80% of Full Power
P-70 ....................................................................approx. 70% of Full Power
P-60 ....................................................................approx. 60% of Full Power
P-50 ....................................................................approx. 50% of Full Power
P-40 ....................................................................approx. 40% of Full Power
P-30 ....................................................................approx. 30% of Full Power
P-20 ....................................................................approx. 20% of Full Power
P-10 ....................................................................approx. 10% of Full Power
P-0 ......................................................No powerthroughoutthecookingtime
MINUTE PLUS pad, Cook center pads, Defrost center pads, Number selection
pads,PowerLevelpad,Timer/Clockpad,Stop/Clearpad,START pad,
ReheatandPopcorn.
OvenCavityLight Yes
SafetyStandard UL Listed FCC Authorized
DHHSRules,CFR,Title21,Chapter1,SubchapterJ

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a qualified electrician and have it replaced with a properly grounded
three-pronged wall receptacle or have a grounding adapter properly
groundedandpolarized.Iftheextensioncordmustbeused,itshouldbe
a 3-wire, 15 amp. or higher rated cord. Do not drape over a countertop
ortablewhereitcanbepulledonbychildrenortrippedoveraccidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR RE-
MOVE THE ROUND GROUNDING PRONG FROM THIS
PLUG.
OVEN DIAGRAM
1. One touch door open button.
Push to open door.
2. Door latches.
The oven will not operate unless the
door is securely closed.
3. Removable turntable support.
4. Removable turntable.
The turntable will rotate clockwise or
counterclockwise.
5. Oven lamp.
It will light when oven is operating or
door is opened.
6. Oven door with see-through window.
7. Ventilation openings. (Rear)
8. Auto-Touch control panel.
9. Time display: Digital display, 99
minutes 99 seconds.
10.Wave guide cover.
11.Power supply cord
TOUCH CONTROL PANEL
3-Pronged
Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
NOTE:
The directed features are disa-
bled after one minute when the
ovenisnotinuse.Thesefeatures
are automatically enabled when
the door is opened and closed or
theSTOP/CLEARpadispressed.
R-501FK/FW
1
65
4
210
11
9
7
8
3

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OPERATION
DESCRIPTION OF OPERATING SEQUENCE
Thefollowingisadescriptionofcomponentfunctionsduring
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
primaryinterlockswitch.(Inthiscondition,themonitorswitch
contactsareopened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (Figure O-1).
1. Thedisplaywillshowflashing"88:88".
Tosetanyprogramorsettheclock,youmustfirsttouch
theSTOP/CLEAR pad. The display willclear, and " : "
will appear.
COOKING CONDITION
Program desired cooking time by touching the NUMBER
pads. Program the power level by touching the POWER
LEVEL pad and then a Number pad.
When the START pad is touched, the following operations
occur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure O-2)
RELAY CONNECTED COMPONENTS
RY-1 oven lamp/turntable motor/fan motor
RY-2 power transformer
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.3 volts
A.C. output on the filament winding, and approximately
2370 volts A.C. on the high voltage winding.
3. Thefilamentwindingvoltageheatsthemagnetronfilament
andtheH.V.windingvoltageissenttoa voltagedoubler
circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feed-
box, and then into the cavity where the food is placed to
be cooked.
5. Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The oven
will revert to the OFF condition.
6. Whenthedoorisopenedduringacookcycle,themonitor
switch, door sensing switch, primary interlock switch,
relay (RY1) and secondary interlock relay are activated
with the following results. The circuits to the turntable
motor, the cooling fan motor, and the high voltage
componentsarede-energized,theovenlampremainson,
andthedigitalread-outdisplaysthetimestillremainingin
the cook cycle when the door was opened.
7. Themonitorswitchelectrically monitorstheoperationof
theprimaryinterlockswitchandsecondaryinterlockrelay
andismechanicallyassociatedwiththedoorsothatitwill
functionin the followingsequence.
(1) When the door opens from the closed position, the
secondary interlock relay (RY2) and primary interlock
switch open their contacts. And contacts of the relay
(RY1)remainsclosed.Thenthemonitorswitchcontacts
close.
(2) When the door is closed from the open position, the
monitor switch contacts open first. Then the contacts of
the primary interlock switch and door sensing switch
close. And contacts of the relay (RY1) open.
Iftheprimaryinterlockswitch andsecondaryinterlockrelay
(RY2)failwiththecontactsclosedwhenthedoorisopened,
the closing of the monitor switch contacts will form a short
circuit through the C/T fuse, primary interlock switch, relay
(RY1)andsecondaryinterlockrelay(RY2),causingtheC/T
fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
WhenVariableCookingPowerisprogrammed,the120volts
A.C. is supplied to the power transformer intermittently
throughthecontactsofrelay(RY-2)whichisoperatedbythe
controlunitwithina32secondtimebase.Microwavepower
operation is as follows:
VARI-MODE ON TIME OFF TIME
Power 10(P-HI) 32 sec. 0 sec.
(100% power)
Power 9(P-90) 30 sec. 2 sec.
(approx. 90% power)
Power 8(P-80) 26 sec. 6 sec.
(approx. 80% power)
Power 7(P-70) 24 sec. 8 sec.
(approx. 70% power)
Power 6(P-60) 22 sec. 10 sec.
(approx. 60% power)
Power 5(P-50) 18 sec. 14 sec.
(approx. 50% power)
Power 4(P-40) 16 sec. 16 sec.
(approx. 40% power)
Power 3(P-30) 12 sec. 20 sec.
(approx. 30% power)
Power 2(P-20) 8 sec. 24 sec.
(approx. 20% power)
Power 1(P-10) 6 sec. 26 sec.
(approx. 10% power)
Power 0(P-0) 0 sec. 32 sec.
(0% power)
Note: TheON/OFFtimeratiodoesnotcorrespondwiththe
percentageofmicrowavepower,becauseapprox.2
seconds are needed for heating of the magnetron
filament.

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Figure O-2 Oven Schematic - Cooking Condition
Figure O-1 Oven Schematic - Off Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. Door Closed
2. CLOCK APPEARS ON DISPLAY
SCHEMATIC
3. VARIABLE COOKING CONTROL "HIGH"
2. COOKING TIME PROGRAMMED
1. DOOR CLOSED
NOTE: CONDITION OF OVEN
4. "START" PAD TOUCHED
Note:* Indicates component
CAVITY
TEMPERATURE
FUSE
120VAC
60Hz
COM.
RED
RED
WHT
WHT
WHT
WHT
BRN
WHT
WHT
WHT
ORG
RED
WHT
WHT
GRN
N.O.
B2
B1
CONTROL UNIT
C/T
FUSE
N.O.
(RY2)
COM.
DOOR
SENSING
SWITCH
TTM FM
OL TURN
TABLE
MOTOR
FAN
MOTOR
OVEN
LAMP
MONITOR
SWITCH
PRIMARY
INTERLOCK
SWITCH
POWER
TRANSFORMER
MAGNETRON
HIGH
VOLTAGE
CAPACITOR
ORG
WHT
SECONDARY
INTERLOCK
RELAY
ORG
BRN
ORG
ORG
RED
RED
GRY
GRY
GND
WHT
F3
F2
F1
SENSOR
(RY1)
OVEN
LAMP
RELAY
COM. N.O.
HUMIDITY
COM.
N.C. HIGH
VOLTAGE
RECTIFIER
ORG
CAVITY
TEMPERATURE
FUSE
120VAC
60Hz
COM.
RED
RED
WHT
WHT
WHT
WHT
BRN
WHT
WHT
WHT
ORG
RED
WHT
WHT
GRN
N.O.
B2
B1
CONTROL UNIT
N.O.
(RY2)
COM.
DOOR
SENSING
SWITCH
TTM FM
OL TURN
TABLE
MOTOR
FAN
MOTOR
OVEN
LAMP
MONITOR
SWITCH
PRIMARY
INTERLOCK
SWITCH
POWER
TRANSFORMER
MAGNETRON
HIGH
VOLTAGE
CAPACITOR
ORG
WHT
SECONDARY
INTERLOCK
RELAY
ORG
BRN
ORG
ORG
RED
GRY
GRY
GND
WHT
F3
F2
F1
SENSOR
(RY1)
OVEN
LAMP
RELAY
COM. N.O.
HUMIDITY
COM.
N.C. HIGH
VOLTAGE
RECTIFIER
ORG
C/T
FUSE
RED

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DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
Thedoorisopenedbypushingtheopenbuttononthecontrol
panel, refer to the Figure D-1. When the open button is
pushed, the open button pushes up the switch lever, and
then the switch lever pushes up the latch head. The latch
heads are moved upward and released from latch hook.
Now the door will open.
Figure D-1. Door Open Mechanism
DOOR SENSING AND PRIMARY INTERLOCK
SWITCHES
Theprimaryinterlockswitchismountedinthelowerposition
ofthelatchhookandthedoorsensingswitchinthesecond-
ary interlock system is mounted in the upper position of the
latchhook.Theyareactivatedbythelatchheadsonthedoor.
Whenthedoorisopened,theswitchesinterruptthepowerto
allhighvoltagecomponents.Acookcyclecannottakeplace
untilthedoorisfirmlyclosedtherebyactivatingbothinterlock
switches. The secondary interlock system consists of the
doorsensingswitchandsecondaryinterlockrelaylocatedon
the control circuit board.
MONITOR SWITCH
Themonitorswitchisactivated(thecontactsopened)bythe
latch head on the door while the door is closed. The switch
is intended to render the oven inoperative, by means of
blowing the C/T fuse, when the contacts of the secondary
interlockrelay(RY2)andprimaryinterlockswitchfailtoopen
whenthedoorisopened.
Functions:
1. Whenthedoorisopened,themonitorswitchcontactclose
(totheONcondition)duetotheirbeingnormallyclosed.At
thistimethe secondary interlock relay (RY2)andprimary
interlock switch are in the OFF condition (contacts open)
due to their being normally open contact switches.
2. As the door goes to a closed position, the monitor switch
contactsarefirstopenedandthenthedoorsensingswitch
andtheprimaryinterlockswitchcontactsclose.(Onopening
the door, each of these switches operate inversely.)
3. If the door is opened, and the secondary interlock relay
(RY2)andprimary interlock switch contacts failtoopen,
the C/T fuse blows simultaneously with closing of the
monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN C/T FUSE
TEST THE DOOR SENSING SWITCH, SEC-
ONDARY INTERLOCK RELAY (RY2), RELAY
(RY1), PRIMARY INTERLOCK SWITCH AND
MONITOR SWITCH FOR PROPER OPERA-
TION.(REFER TO CHAPTER "TEST PROCE-
DURE").
NOTE: C/T FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
TURNTABLE MOTOR
The turntable motor rotates the turntable located on the
bottomofthe oven cavity, so thatthefoods on the turntable
cookevenlyduringcooking.Theturntablemayturnineither
direction.
COOLING FAN MOTOR
Thecoolingfanmotordrivesabladewhichdrawsexternalcool
air.Thiscoolairisdirectedthrough the airvanessurrounding
themagnetronandcoolsthemagnetron.Thisairischanneled
throughtheovencavitytoremovesteamandvaporsgivenoff
from the heating foods. It is then exhausted through the
exhausting air vents at the oven cavity.
CAVITY TEMPERATURE FUSE
The cavity temperature fuse located on the top of the oven
cavity,isdesignedtopreventdamagetotheovenbyfire.Ifthe
foodloadisovercooked,byeithererrorincooktimeordefect
in the control unit, the cavity temperature fuse will open.
Undernormaloperation,thecavitytemperaturefuseremains
closed. However, when abnormally high temperatures are
reachedwithintheovencavity,thecavitytemperaturefusewill
open at 302OF(150OC) causing the oven to shut down.
NOTE: This is fuse. It does not reset.
C/T TEMPERATURE FUSE
TheC/Tfuselocatednearthemagnetronisdesignedtoprevent
damagetothemagnetronifanoverheatedconditiondevelops
inthetubeduetocoolingfanfailure,obstructedairguide,dirty
or blocked air intake, etc.
Under normal operation, the C/T fuse remains closed. How-
ever,whenabnormallyhightemperatures are reachedwithin
themagnetron,theC/Tfusewillopenat302OF(150OC)causing
the oven to shut down.
1. TheC/Tfuseblows whenthecontacts(COM-NO)ofthe
secondary interlock relay (RY2) and primary interlock
switchremainclosedwiththeoven dooropenandwhen
the monitor switch closes.
2. If the wire harness or electrical components are short-
circuited, this monitor fuse blows to prevent an electric
shock or fire hazard.
NOTE: This is fuse. It does not reset.
Door Sensing
Switch
Monitor Switch
Switch Lever
Primary Interlock
Switch
Latch Heads
Door

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TROUBLESHOOTING GUIDE
Nevertouchanypartinthecircuitwithyourhandoranuninsulatedtoolwhilethepowersupplyisconnected.
Whentroubleshootingthemicrowave oven,itishelpfultofollow theSequenceofOperationinperforming thechecks.Many
ofthepossiblecausesoftroublewillrequirethataspecifictestbeperformed.Thesetestsaregivenaprocedureletterwhich
will be found in the "Test Procedure "section.
IMPORTANT: IftheovenbecomesinoperativebecauseofablownC/Tfuse,checkthemonitorswitch,relay(RY1)secondary
interlock relay (RY2), door sensing switch and primary interlock switch before replacing the C/T fuse. If the
C/T fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA019/KIT as an assembly.
IMPORTANT: Whenevertroubleshootingisperformedwiththepowersupplycorddisconnected.Itmayin,somecases,be
necessary to connect the power supply cord after the outer case has been removed, in this event:
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensurethatthe leadsremainisolatedfromothercomponentsandovenchassisbyusing insulationtape.
6. After that procedure, reconnect the power supply cord.
When the testing is completed
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Reconnect the leads to the primary of the power transformer.
5. Reinstall the outer case (cabinet).
6. Reconnect the power supply cord after the outer case is installed.
7. Run the oven and check all functions.

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AMAGNETRON ASSEMBLY TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
Home fuse or circuit breaker blows
whenpowercordispluggedintowall
receptacle
C/T fuse blows when power cord is
plugged into wall receptacle.
All letters and indicators do not ap-
pear in display when power cord is
first plugged into wall outlet.
Display does not operate properly
when STOP/CLEAR key is touched.
(Buzzershouldsoundand":"ortime
of day should appear in display.)
Oven lamp does not light when door
is opened.
Oven lamp does not go out when
door is closed.
Oven lamp lights but fan motor and
turntable motor do not operate.
Oven does not go into cook cycle
when START pad is touched
Ovenseemstobeoperatingbutlittle
or no heat is produced in oven load.
(Food incompletely cooked or not
cooked at all at end of cook cycle.)
Oven goes into a cook cycle but
extremely uneven heating is pro-
duced in oven load (food).
Oven does not cook properly when
programmed for Cooking Power P-
50 mode. (Operates properly on
Cooking P-HI (HIGH) mode.)
Oven goes into COMPU DEFROST
but food is not defrosted well.
OFF
CONDITION
PROBLEM
CONDITION
SHORT IN POWER CORD SHORT OR OPENED WIRING MAGNETRON POWER TRANSFORMER H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE CAPACITOR CAVITY TEMPERATURE FUSE C/T FUSE SECONDARY INTERLOCK SYSTEM PRIMARY INTERLOCK SWITCH MONITOR SWITCH C/T FUSE OVEN LAMP OR SOCKET COOLING FAN MOTOR TURNTABLE MOTOR TOUCH CONTROL PANEL WRONG OPERATION LOW VOLTAGE DIRTY OVEN CAVITY KEY UNIT RELAY (RY1) COMPU DEFROST FOIL PATTERN ON PWB.
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
RE RE ABCDEEFFGH RE RE CK I CK CK CK JKLM
COOKING
CONDITION
CK = Check / RE = Replace

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BPOWER TRANSFORMER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of
the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be
approximately 90 ohms; the resistance of the filament coil should be less than 1 ohm.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
(HIGHVOLTAGESAREPRESENTATTHE HIGH VOLTAGETERMINAL,SODONOTATTEMPTTO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
4. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check
across the magnetron filament leads should indicate less than 1 ohm.
5. Totestforashortedmagnetron,connecttheohmmeterleadsbetweenthemagnetronfilamentleads
and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance
the magnetron is grounded and must be replaced.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
Thefollowingtestprocedureshouldbecarriedoutwiththemicrowaveoveninafullyassembledcondition
(outer case fitted).
HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD
BE OBSERVED.
Power output of the magnetron can be measured by performing a water temperature rise test. This test
shouldonlybeusedifabovetestsdonotindicateafaultymagnetronandthereisnodefectinthefollowing
componentsorwiring:siliconrectifier,highvoltagecapacitorandpowertransformer.Thistestwillrequire
a 16 ounce (453cc) measuring cup and an accurate mercury thermometer or thermocouple type
temperature tester. For accurate results, the following procedure must be followed carefully:
1. Fillthemeasuringcupwith16oz.(453cc)oftapwaterandmeasurethetemperatureofthewaterwith
athermometerorthermocoupletemperaturetester.Stirthethermometerorthermocouplethroughthe
water until the temperature stabilizes. Record the temperature of the water.
2. Place the cup of water in the oven. Operate oven at POWER 10(HIGH) selecting more than 60
secondscooktime.Allowthewatertoheatfor60seconds,measuringwithastopwatch,secondhand
of a watch or the digital read-out countdown.
3. Remove the cup from the oven and again measure the temperature, making sure to stir the
thermometer or thermocouple through the water until the maximum temperature is recorded.
4. Subtractthecoldwatertemperaturefromthehotwatertemperature.Thenormalresult should be 38
to 78OF(21Oto 42.6OC) rise in temperature. If the water temperatures are accurately measured and
tested for the required time period the test results will indicate if the magnetron tube has low power
output(lowriseinwatertemperature)whichwouldextendcookingtimeorhighpoweroutput(highrise
in water temperature) which would reduce cooking time. Because cooking time can be adjusted to
compensate for power output, the magnetron tube assembly should be replaced only if the water
temperaturerisetestindicatesapoweroutputwellbeyondthenormallimits.Thetestisonlyaccurate
if the power supply line voltage is 120 volts and the oven cavity is clean.

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TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Ifthecapacitorisopen,nohighvoltagewillbeavailabletothemagnetron.Disconnectinputleadsand
check for short or open between the terminals using an ohmmeter.
Checkingwithahighohmscale,ifthehighvoltagecapacitorisnormal,themeterwillindicatecontinuity
for a short time and should indicate an open circuit once the capacitor is charged. If the above is not
thecase, check thecapacitor with anohmmeter to see if it is shorted between either of the terminals
and case. If it is shorted, replace the capacitor.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
DHIGH VOLTAGE CAPACITOR TEST
ECAVITY TEMPERATURE FUSE TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Acontinuitycheckacrossthecavitytemperaturefuseterminalsshouldindicateaclosedcircuitunless
thetemperatureofthe cavitytemperaturefusereachesapproximately302OF(150OC). Anopen cavity
temperaturefuseindicatesoverheatingoftheoven,exchangethe cavitytemperaturefuseandcheck
inside of oven cavity and for improper setting of cooking time or operation of control unit. Check for
restricted air flow through the vent holes of the oven cavity, especially the cooling fan and air guide.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
C/T FUSE TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. AcontinuitycheckacrosstheC/Tfuseterminalsshouldindicateaclosedcircuitunlessthetemperature
oftheC/Tfuse reachesapproximately302OF(150OC).AnopenC/Tfuseindicates overheatingofthe
magnetron. Check for restricted air flow to the magnetron, especially the cooling fan air guide.
CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM
TEMPERATURE,REPLACETEMPERATUREFUSE.
CHIGH VOLTAGE RECTIFIER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance
across the terminals and observe, reverse the leads to the rectifier terminals and observe meter
reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions,
the rectifier is probably defective and should be replaced.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE:Besure touseanohmmeter thatwillsupplya forwardbiasvoltage of morethan6.3 volts.

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TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Isolatetheswitchandconnecttheohmmetertothecommon(COM.)andnormallyopen(NO)terminal
of the switch. The meter should indicate an open circuit with the door open and a closed circuit with
the door closed. If improper operation is indicated, replace the primary interlock switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
SECONDARYINTERLOCKSYSTEMTEST
DOORSENSINGSWITCH
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Isolatetheswitchandconnecttheohmmetertothecommon(COM.)andnormallyopen(NO)terminal
of the switch. The meter should indicate an open circuit with the door open and a closed circuit with
the door closed. If improper operation is indicated, replace the door sensing switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
NOTE: Ifthedoorsensingswitchcontactsfailintheopenpositionandthedoorisclosed,thecoolingfan,
turntable and oven light will be activated by RY1.
SECONDARYINTERLOCKRELAY(RY2)
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnecttwo(2)wireleadsfromthemaletabterminalsoftheSecondaryInterlockRelay.Checkthe
stateoftherelaycontactsusingaohmmeter.Therelaycontactsshouldbeopen.Iftherelaycontacts
are closed, replace the circuit board entirely or the relay itself.
5. Reconnect all leads removed from components during testing.
6. Reinstall the outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
F PRIMARYINTERLOCKSWITCHTEST
5. IftheC/Tfuseisblownwhenthedoorisopened,checkthesecondaryinterlockrelay,primaryinterlock
switchandmonitorswitchaccordingtothe"TESTPROCEDURE"forthoseswitchesbeforereplacing
theblown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN C/T FUSE, TEST THE SECONDARY INTERLOCK
RELAY, PRIMARY INTERLOCK SWITCH, DOOR SENSING SWITCH AND MONITOR
SWITCHFORPROPEROPERATION.
IftheC/Tfuse isblownbyimproperswitchoperation,theC/Tfuseandmonitorswitchmustbereplaced
with"C/Tfuseandmonitorswitchassembly"partnumberFFS-BA019/KIT,evenifthemonitorswitch
operatesnormally.TheC/Tfuseand monitorswitchassemblyiscomprisedofa20 ampere fuseand
switch.
6. Reconnectallleadsremovedfromcomponentsduringtesting.
7. Reinstallthe outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.

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Primary
Interlock Switch Monitor Switch
Screw Driver
Ohmmeter
Red White/ White
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter
andohmmeter.Inthisservicemanual,thetouchcontrolpanelassemblyisdividedintotwounits,Control
Unit and Key Unit, and also the Control Unit is divided into two units, LSI Unit and Power Unit, and
troubleshooting by unit replacement is described according to the symptoms indicated.
Before testing,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.
1. Key Unit.
NOTE :
1)CheckKeyunitribbonconnectionbeforereplacement.
2)Re-install the outer case(cabinet).
3) Reconnect the power supply cord after the outer case is installed.
4) Run the oven and check all functions.
The following symptoms indicate a defective key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
If the Key unit is defective.
ITOUCHCONTROLPANELASSEMBLYTEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Before performing this test, make sure that the primary interlock switch and the secondary interlock
relayareoperatingproperly,accordingtotheaboveSwitchTestProcedure.Disconnectthewirelead
fromthemonitor switch (COM) terminal.Check the monitor switch operationby using the ohmmeter
asfollows.Whenthedoorisopen,themetershouldindicateaclosedcircuit.Whenthemonitorswitch
actuatoris pushed by ascrew driver through thelower latch hole onthe front plate ofthe oven cavity
withthedooropened(inthisconditiontheplungerofthemonitorswitchispushedin),themetershould
indicate an open circuit. If improper operation is indicated, the switch may be defective. After testing
the monitor switch, reconnect the wire lead to the monitor switch (COM) terminal and check the
continuity of the monitor circuit.
5. Reconnectallleadsremovedfromcomponentsduringtesting.
6. Reinstallthe outer case (cabinet).
7. Reconnect the power supply cord after the outer case is installed.
8. Run the oven and check all functions.
GMONITORSWITCHTEST

15
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1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Replace the Key unit.
5) Reconnect all leads removed from components during testing.
6) Re-install the outer case (cabinet).
7) Reconnect the power supply cord after the outer case is installed.
8) Run the oven and check all functions.
2. Control Unit
Thefollowingsymptomsindicateadefectivecontrolunit.Beforereplacingthecontrolunit,performthe
Key unit test (Procedure J) to determine if control unit is faulty.
2-1 In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
When testing is completed,
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Reconnect all leads removed from components during testing.
5) Re-install the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions..
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
JKEYUNITTEST
1.Disconnect the powersupply cord, andthen remove outercase.
2. Open the door and block it open.
3.Dischargehighvoltagecapacitor.
4. Isolate the key unit with the control panel frame to be tested.
5. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the
circuit between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is
pressed,theohmmetershouldindicateshortcircuit.Whenthepadisreleased,theohmmetershould
indicateopencircuit.Ifincorrectreadingsareobtained,thekeyunitisfaultyandmustbereplaced.About
theother pads, the abovemethod may be used
6. Reconnect all leads removed from components during testing.
7. Re-install the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.

16
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WARNING : The oven should be fully assembled before following procedure.
(1) Place one cup of water in the center of the turntable tray in the oven cavity.
(2) Close the door, touch the “ DEFROST ” pad once.
(3) Touch the number pad "2" and then touch the number pad "5".
(4) Touch the start pad.
(5) The oven is in Compu Defrost cooking condition.
(6) The oven will operate as follows. (in case of Steak/Chops 0.5lb)
WEIGHT 1ST STAGE 2ND STAGE
0.5lb LEVEL TIME LEVEL TIME
60% 1min 3sec. 40% 24sec.
(7) If improper operation is indicated, the control unit is probably defective and should be checked.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the leads to the primary of the power transformer.
5. Ensure that these leads remain isolated from other components and oven chassis by using insulation
tape.
6. After that procedure, re-connect the power supply cord.
7. Remove the outer case and check voltage between the normal open terminal of the relay RY1 and the
normal open terminal of the relay RY2 on the control unit with an A.C. voltmeter.The meter should
indicate 120 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
DC. voltage indicated ............. Defective relay.
DC. voltage not indicated ........ Check diode which is connected to the relay coil. If diode is good,
control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 Approx. 12.0V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 Approx. 11.0V D.C. Power transformer
8. Disconnect the power supply cord, and then remove outer case.
9. Open the door and block it open.
10. Discharge high voltage capacitor.
11. Reconnect all leads removed from components during testing.
12. Re-install the outer case (cabinet).
13. Reconnect the power supply cord after the outer case is installed.
14. Run the oven and check all functions.
LCOMPU DEFROST TEST
Key Unit
KRELAY TEST
8
POPCORN
DE FR OS T
START
POWER
LEVEL
MINUTE
PLUS
TIMER
CLOCK
1
4
7
5
2
8
0
9
3
6
COOK
REHEAT
7 6 5 4 3 2 1
91011121314
STOP
CLEAR
Pin
No. G14
Pin
No. G1
Key unit ribbon cable
Key unit (Membrane Switch) front view

17
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M FOIL PATTERN ON THE PRINTED WIRING BOARD TEST
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary
on the PWB, this foil pattern acts as a fuse.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
1) Disconnectthepowersupplycord,andthenremoveoutercase.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
1 Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
2 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
5) Makeavisualinspection ofthevaristor.
Checkforburneddamageandexamine
the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance which is
approximately540ohms ±20%).Ifany
abnormalconditionisdetected,replace
the defective parts.
6) Reconnect all leads removed from components during testing.
7) Re-install the outer case (cabinet).
8) Reconnect the power supply cord after the outer case is installed.
9) Run the oven and check all functions.
2.Followthetroubleshootingguidegivenbelow,ifindicatordoesnotlightupafterabovecheckandrepairs
are finished.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using
insulationtape.
6) After that procedure, re-connect the power supply cord.
7) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
1 The rated AC voltage is not present between Check supply voltage and oven power cord.
the normal open terminal of the relay RY1 and
the normal open terminal of the relay RY2
2 The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and repair.
8) Disconnect the power supply cord, and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
1. Foil pattern check and repairs.
MR
7
MCR
M27A
94V
-
R
T1
1
RY2
(J1)
a
b
cd

18
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This circuit consists of 22 segments and 3 common
electrodes using a Liquid Crystal Display.
3) PowerSourceCircuit
This circuit generates voltages necessary in the
control unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
Symbol Voltage Application
VC -5V LSI(IC1)
4) RelayCircuit
A circuit to drive the magnetron, fan motor, turntable
motor and light the oven lamp.
5) BuzzerCircuit
The buzzer is responsive to signals from the LSI to
emit audible sounds (key touch sound and completion
sound).
6) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
It accompanies a very small error because it works on
commercialfrequency.
7) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
8) BackLightCircuit
A circuit to drive the back light (Light emitting diodes
LD1-LD4).
TOUCHCONTROLPANELASSEMBLY
OUTLINEOFTOUCHCONTROLPANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit
and LSI Unit).
The principal functions of these units and the signals
communicatedamongthemareexplainedbelow.
KeyUnit
The key unit is composed of a matrix, signals generated in
the LSI are sent to the key unit through P20, P21, P22,
P23, P24, P25, P26 and P27.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P41,
P45, P47, P70 and AN2 to perform the function that was
requested.
ControlUnit
Control unit consists of LSI, reset circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit,
synchronizing signal circuit and back light circuit.
1) ResetCircuit
This circuit generates a signal which resets the LSI to
the initial state when power is supplied.
2) IndicatorCircuit