Sharp R-370EK User manual

R-370EK
R-370ES
In the interest of user-safety the oven should be restored to its
originalconditionandonlypartsidenticaltothosespecifiedshould
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..)
TABLE OF CONTENTS 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 ............................................................................................................................10
TEST PROCEDURE............................................................................................................................................12
TOUCH CONTROL PANEL.................................................................................................................................21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE................................................................26
PICTORIAL DIAGRAM ........................................................................................................................................33
POWER UNIT CIRCUIT ......................................................................................................................................34
CPU UNIT CIRCUIT ............................................................................................................................................35
PRINTED WIRING BOARD .................................................................................................................................36
PARTS LIST ........................................................................................................................................................37
PACKING AND ACCESSORIES .........................................................................................................................39
S4112R370EPS/
R-370EK
R-370ES
MICROWAVEOVEN
MODELS
SERVICEMANUAL
SHARP CORPORATION This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
Veverage
PopcornRice
Compu
Defrost
KitchenTimer
Clock
Frozen
Entree
Fish
Seafood
Chicken
Breast
Reheat
Sensor
Baked
Potatoes
Ground
Meat
Fresh
Vegetables
Frozen
Vegetables
Rolls &
Muffins
Custom
Help
Power
Level
STOP
Clear
Minute Plus
START
12345
67890

R-370EK
R-370ES
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROWAVE
ENERGY
(a) Do not operate 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
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 and
latches, (5) evidence of dropping or abuse.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
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 manual before the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be
performed on each oven prior to 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 ELECTRONICS
CORPORATION immediately @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.
ServicepersonnelshouldinformSHARPELECTRONICSCORPORATIONofanycertifiedunitfound
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.

1
R-370EK
R-370ES
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(thatisthe connecting lead of the high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Whenever troubleshooting is performed the power supply
mustbedisconnected.Itmay,insomecases,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. Reconnectthe power supply cordaftertheouter 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. Reconnectthe power supply cordaftertheouter case is
installed.
4. Run the oven and check all functions.
Microwave ovens should not be run empty. To test for 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 twominuteshas elapsed (timeratzero)
carefully check that the water is now hot. If the water
remainscold,carryoutBeforeServicingprocedureandre-
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 Voltage

2
R-370EK
R-370ES
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(throughtheusefullifeoftheoven),5mW/cm2atanypoint5cmormorefrom the external
surface of the oven.
2) Safety interlock switches
Primary interlock 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. Preparation for testing:
Before beginning the actual measurement of leakage, proceed as follows:
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±5˚C (68˚F) in the center of the oven cavity.
The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.)
and made of an electrically nonconductive material such as glass or plastic.
Theplacing of thisstandardloadin the ovenisimportant not only toprotectthe oven, butalsotoinsure that anyleakage
is measured accurately.
4) Set the cooking control on Full Power Cooking Mode.
5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed,
replace it with 275 ml of cool water.
C. Leakage test:
Closed-door leakage test (microwave measurement)
1) Grasptheprobeofthesurveyinstrumentandholditperpendiculartothegapbetweenthedoorandthebodyoftheoven.
2) Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication on
the meter.
3) Checkforleakageatthedoorscreen,sheetmetalseamsandotheraccessiblepositionswherethecontinuityofthemetal
has been breached (eg., around the switches, indicator, and vents).
Whiletestingforleakagearoundthedoorpullthedoorawayfromthefrontoftheovenasfarasispermittedbytheclosed
latch assembly.
4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm2.
NOTE: After servicing, record data on service invoice and microwave leakage report.

3
R-370EK
R-370ES
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
MICROWAVE OVEN
R-370EK/ R-370ES
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVEN, R-370EK, R-370ES.
It is recommended that service personnel carefully study the entire
text of this manual so that they will be qualified to render satisfactory
customer service.
Check the interlock switches and the door seal carefully. Special
attention should be given to avoid electrical shock and microwave
radiation hazard.
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
Certaininitialpartsareintentionallynotgroundedandpresent
a risk of electrical shock only during servicing. Service
personnel - Do not contact the following parts while the
appliance is energized;
HighVoltageCapacitor,PowerTransformer,Magnetron,High
Voltage Rectifier Assembly, High Voltage Harness;
If provided, Vent Hood, Fan assembly, Cooling Fan Motor.
Allthepartsmarked“*”onpartslistareusedatvoltagesmorethan
250V.
Removal of the outer wrap gives access to voltage above 250V.
Allthepartsmarked“∆”onpartslistmaycauseunduemicrowave
exposure, by themselves, or when they are damaged, loosened
or removed.
PRODUCT DESCRIPTION
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST

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R-370EK
R-370ES
ITEM DESCRIPTION
Power Requirements 120 Volts / 13.5 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output 1000 watts (IEC TEST PROCEDURE)
Operating frequency of 2450MHz
Case Dimensions Width 17-1/4"
Height 13-3/8"
Depth 18-3/8"
Cooking Cavity Dimensions Width 13-3/4"
Height 7-1/4"
1.4 Cubic Feet Depth 16-1/2"
Control Complement Touch Control System
Clock ( 1:00 - 12:59 )
Timer (0 - 99 min. 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
HIGH................................................Full power throughout the cooking time
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 power throughout the cooking time
SENSOR COOKING pads , INSTANT ACTION pads
COMPU DEFROST pads, Number selection pads
CUSTOM HELP PAD, POWER LEVEL pad,
KITCHEN TIMER/CLOCK pad
STOP/CLEAR pad, MINUTE PLUS /START pad
Oven Cavity Light Yes
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
SPECIFICATION
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.
In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the
electric current.
WARNING: Improper use of the grounding plug can result in a risk of electric shock.
Electrical Requirements
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.
Where a two-pronged wall-receptacle is encountered, it is the personal responsibility and obligation of the customer to

5
R-370EK
R-370ES
contact a qualified electrician and have it replaced with a properly
grounded three-pronged wall receptacle or have a grounding adapter
properly grounded and polarized. If the extension cord must be used, it
should be a 3-wire, 15 amp. or higher rated cord. Do not drape over a
countertopor table whereit can bepulledon by childrenortripped over
accidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR RE-
MOVE THE ROUND GROUNDING PRONG FROM THIS
PLUG.
3-Pronged Plug Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
OVEN DIAGRAM
1. Door handle
Pull to open door.
2. Auto-Touch control panel
3. Display: 99 minutes, 99 seconds
4. Oven door with see-through window
5. Safety door latch
The oven will not operate unless the door is
securely closed.
6. Door hinges
7. Door seals and sealing surface
8. Turntable motor shaft
9. Removable turntable support
Carefullyplacetheturntablesupportinthecenter
of the oven floor.
10.Removable turntable
Place the turntable on the turntable support
cecurely. The turntable will rotate clockwise or
counterclockwise. Only remove for cleaning.
11.Ventilation openings (Rear)
12.Oven light
It will light when oven is operating or door is
opened.
13.Wave guide cover: DO NOT REMOVE.
NOTE:
The directed features are disabled after three minutes when the oven is not in use. These features are
automatically enabled when the door is opened and closed or the STOP/ CLEAR pad is pressed.
TOUCH CONTROL PANEL
;;
;;
;;
;;
11 12
7
5
3
2
1
9
4
813
6
10
Beverage
Popcorn Rice
Compu
Defrost
Kitchen Timer
Clock
Frozen
Entree
Fish
Seafood
Chicken
Breast
Reheat
Sensor
Baked
Potatoes
Ground
Meat
Fresh
Vegetables
Frozen
Vegetables
Rolls &
Muffins
Custom
Help
Power
Level
STOP
Clear
Minute Plus
START
12345
67890
COOK SENSOR LBS DEF HELP

6
R-370EK
R-370ES
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
Thefollowingisadescriptionofcomponentfunctionsduring
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
primary interlock switch. (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (Figure O-1).
1. The display will show "SHARP SIMPLY THE BEST
PRESS CLEAR AND PRESS CLOCK".To set any
programorsettheclock,youmustfirsttouchtheSTOP/
CLEARpad.Thedisplaywillclear,and" : "willappear.
COOKING CONDITION
Program desired cooking time by touching the NUMBER
pads. Program the power level by touching the POWER
LEVEL 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 3.4 volts
A.C. output on the filament winding, and approximately
2300 volts A.C. on the high voltage winding.
3. The filament winding voltage heats the magnetron
filamentandtheH.V.windingvoltageissenttoavoltage
doubler 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. When the door is opened during a cook cycle, the
monitor switch, door sensing switch, primary interlock
switch,relay (RY1) andsecondary interlock relay(RY2)
areactivatedwiththefollowingresults.Thecircuitstothe
turntable motor, the cooling fan motors, and the high
voltage components are de-energized, the oven lamp
remainson,andthedigitalread-outdisplaysthetimestill
remaining in the cook cycle when the door was opened.
7. Themonitorswitchelectricallymonitorsthe operationof
the primary interlock switch and secondary interlock
relay(RY2)andismechanicallyassociatedwiththedoor
so that it will function in the following sequence.
(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 and secondaryinterlockrelay
(RY2)failwiththecontactsclosedwhenthedoorisopened,
the closing of the monitor switch contacts will form a short
circuit through the monitor fuse, primary interlock switch,
relay (RY1) and secondary interlock relay (RY2), causing
the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
voltsA.C.issuppliedtothepowertransformerintermittently
throughthecontactsofrelay(RY2)whichisoperatedbythe
controlunitwithina32secondtimebase.Microwavepower
operation is as follows:
VARI-MODE DISPLAY ON TIME OFF TIME
100% HIGH 32 sec. 0 sec.
approx. 90% power P-90 30 sec. 2 sec.
approx. 80% power P-80 26 sec. 6 sec.
approx. 70% power P-70 24 sec. 8 sec.
approx. 60% power P-60 22 sec. 10 sec.
approx. 50% power P-50 18 sec. 14 sec.
approx. 40% power P-40 16 sec. 16 sec.
approx. 30% power P-30 12 sec. 20 sec.
approx. 20% power P-20 8 sec. 24 sec.
approx. 10% power P-10 6 sec. 26 sec.
0% power P-0 0 sec. 32 sec.
Note: The ON/OFF time ratio does not correspond with
the percentage of microwave power, because
approx. 2 seconds are needed for heating of the
magnetron filament.
POWER OUTPUT REDUCTION
Iftheovenissetformorethan30minutesat80,90or100%
power level, after the first 30 minutes the power level will
automatically adjust itself to 70% power to avoid overcook-
ing.
SENSOR COOKING CONDITION
Using the SENSOR function, the food is cooked without
figuringtime,powerlevelorquantity.Whentheovensenses
enough steam from the food, it relays the information to its
microprocessor which will calculate the remaining cooking
timeandpowerlevelneededforbestresults.Whenthefood

7
R-370EK
R-370ES
is cooked, water vapor is developed. The sensor “senses”
the vapor and its resistance increases gradually. When the
resistance reaches the value set according to the menu,
supplementary cooking is started. The time of supplemen-
tary cooking is determined by experiment with each food
category and inputted into the LSI.
An example of how sensor works: (POTATOES)
1. Potates at room temperature. Vapor is emitted very
slowly.
2. Heat Potates. Moisture and humidity is emitted rapidly.
You can smell the aroma as it cooks.
3. Sensor detects moisture and humidity and calculates
cooking time and variable power.
Cooking Sequence.
1. Operatetheoveninsensorcookingmodebyreferringto
the operation manual.
NOTE: The oven should not be operated on SENSOR
immediately after plugging in the unit. Wait two
minutes before cooking on SENSOR.
2. Thecoilofshut-offrelay(RY-1)isenergized,theturntable
motor, oven lamp and cooling fan motors are turned on,
but the power transformer is not turned on.
3. After about 16 seconds, the cook relay (RY-2) is
energized. The power transformer is turned on,
microwaveenergyisproducedandfirststageisstarted.
The 16 seconds is the cooling time required to remove
any vapor from the oven cavity and sensor.
NOTE: Duringthisfirststage,donotopenthedoorortouch
STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food,thedisplayswitchesovertotheremainingcooking
time and the timer counts down to zero.
At this time, the door may be opened to stir, turn, or
season food.
5. Whenthetimer reaches zero,anaudiblesignalsounds.
The shut-off relay and cook relay are de-energized and
the power transformer, oven lamp, etc. are turned off.
6. OpeningthedoorortouchingtheSTOP/CLEARpad,the
timeofdaywillreappearon the displayandtheovenwill
revert to an OFF condition.
MICROWAVE
MICROWAVE
AH SENSOR

8
R-370EK
R-370ES
Figure O-1. Oven Schematic-Off Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. CLOCK APPEARS ON DISPLAY
120V AC
60 Hz
OVEN
LAMP
AH SENSOR
OVEN LAMP
RELAY TURN-
TABLE
MOTOR FAN
MOTOR
POWER
TRANSFORMER
MONITOR SWITCH
RECTIFIER MAGNETRON
PRIMARY
INTERLOCK
SWITCH
TTM
OL FM
FAN
MOTOR
FM
MONITOR
FUSE 20A
N.O.
N.O.
COM.
COM.
DOOR
SENSING
SWITCH
(RY1)
(RY2)
CONTROL UNIT
SECONDARY
INTERLOCK
RELAY
OVEN THERMAL
CUT-OUT MG. THERMAL CUT-OUT
GRN B2 B1
CAPACITOR
0.94µF
AC 2200V
F1
F3 F2
NOTE: " " indicates components with potential above 250V.
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. COOKING TIME PROGRAMMED
3. VARIABLE COOKING CONTROL "P-HI" (100%)
4. "START" PAD TOUCHED
Figure O-2. Oven Schematic-Cooking Condition
120V AC
60 Hz
OVEN
LAMP
OVEN LAMP
RELAY TURN-
TABLE
MOTOR FAN
MOTOR
POWER
TRANSFORMER
MONITOR SWITCH
RECTIFIER MAGNETRON
PRIMARY
INTERLOCK
SWITCH
TTM
OL FM
FAN
MOTOR
FM
MONITOR
FUSE 20A
N.O.
N.O.
COM.
COM.
DOOR
SENSING
SWITCH
(RY1)
(RY2)
CONTROL UNIT
SECONDARY
INTERLOCK
RELAY
OVEN THERMAL
CUT-OUT MG. THERMAL CUT-OUT
GRN B2 B1
CAPACITOR
0.94µF
AC 2200V
F1
F3 F2
AH SENSOR
NOTE: " " indicates components with potential above 250V.

9
R-370EK
R-370ES
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pulling the door. Refer to the Figure
D-1.
Figure D-1. Door Open Mechanism
DOOR SENSING AND PRIMARY INTERLOCK
SWITCHES
Theprimaryinterlockswitchismountedinthelowerposition
of the latch hook and the door sensing switch in the
secondaryinterlocksystemismountedintheupperposition
of the latch hook. They are activated by the latch heads on
the door. When the door is opened, the switches interrupt
the power to all high voltage components. A cook cycle
cannot take place until the door is firmly closed thereby
activating both interlock switches. The secondary interlock
system consists of the door sensing switch and secondary
interlock relay located on 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 monitor fuse, when the contacts of the second-
ary interlock relay (RY2) and primary interlock switch fail to
open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the secondary interlock relay (RY2)
and primary interlock switch are in the OFF condition
(contactsopen)duetotheirbeingnormallyopencontact
switches.
2. Asthedoorgoestoaclosedposition,themonitorswitch
contacts are first opened and then the door sensing
switch and the primary interlock switch contacts close.
(On opening the door, each of these switches operate
inversely.)
3. If the door is opened, and the secondary interlock relay
(RY2)and primary interlock switchcontactsfailtoopen,
themonitorfuseblowssimultaneouslywithclosingofthe
monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
SECONDARY INTERLOCK RELAY (RY2),
RELAY (RY1), PRIMARY INTERLOCK
SWITCH AND MONITOR SWITCH FOR
PROPER OPERATION. (REFER TO CHAP-
TER "TEST PROCEDURE").
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
TURNTABLE MOTOR
The turntable motor rotates the turntable located on the
bottomof the oven cavity,sothatthe foods ontheturntable
cookevenlyduringcooking.Theturntablemayturnineither
direction.
COOLING FAN MOTOR
The cooling fan motor drives a blade which draws external
cool air. This cool air is directed through the air vanes
surrounding the magnetron and cools the magnetron. This
air is channelled through the oven cavity to remove steam
and vapors given off from the heating foods. It is then
exhausted through the exhausting air vents at the oven
cavity.
MONITOR FUSE
1. Themonitorfuseblowswhenthecontacts(COM-NO)of
thesecondaryinterlockrelay(RY2)andprimaryinterlock
switchremainclosedwiththeoven door openandwhen
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.
OVEN THERMAL CUT-OUT
Thethermalcut-out,locatedonthetopoftheovencavity,is
designed to prevent damage to the oven by fire. If the food
load is overcooked, by either error in cook time or defect in
the control unit, the thermal cut-out will open.
Under normal operation, the oven thermal cut-out remains
closed. However, when abnormally high temperatures are
reachedwithintheovencavity,theoventhermalcut-outwill
open at 257˚F(125˚C), causing the oven to shut down.
MAGNETRON THERMAL CUT-OUT
Thethermalcut-outlocatednearthemagnetronisdesigned
to prevent damage to the magnetron if an over heated
condition develops in the tube due to cooling fan failure,
obstructed air guide, dirty or blocked air intake, etc.
Undernormaloperation,thethermalcut-outremainsclosed.
However,whenabnormallyhightemperatures are reached
within the magnetron, the thermal cut-out will open at
257˚F(125˚C) causing the oven to shut down.
Latch Hook
Door Sensing
Switch
Latch
Heads
Door
Monitor Switch
Primary
Interlock Switch

10
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TROUBLESHOOTING GUIDE
Nevertouchanypartin the circuitwithyourhandoranuninsulatedtoolwhile the power supplyisconnected.
Whentroubleshootingthemicrowave oven,itishelpfultofollowthe SequenceofOperationinperformingthechecks. Many
ofthepossiblecausesoftroublewillrequirethataspecifictestbeperformed.Thesetestsaregivenaprocedureletterwhich
will be found in the "Test Procedure "section.
IMPORTANT: If the oven becomes inoperative because of a blown monitor fuse, check the monitor switch, relay (RY1)
secondary interlock relay (RY2), door sensing switch and primary interlock switch before replacing the
monitor fuse. If the monitor fuse is replaced, the monitor switch must also be replaced. Use part FFS-
BA023WRK0 as an assembly.
IMPORTANT: Whenever troubleshooting is performed with the power supply cord disconnected. It may, in some cases,
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. Ensurethattheleads remainisolatedfromothercomponentsand ovenchassisbyusinginsulationtape.
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 all leads removed from components during testing.
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.

11
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Home fuse or circuit breaker blows
when power cord is plugged into wall
receptacle.
Monitor fuse blows when power cord
is plugged into wall receptacle.
Any letters or 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.
(Buzzer should sound and ":" or time
of day should appear in display.)
Ovenlampdoesnotlightwhendooris
opened.
Ovenlampdoesnotgooutwhendoor
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
Oven seems to be operating but little
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 ex-
tremely uneven heating is produced
in oven load (food).
Oven does not cook properly when
programmedforCookingPowerP-50
mode. (Operates properly on Cook-
ing Power HIGH (100%) mode.)
Oven goes into COMPU DEFROST
but food is not defrosted well.
AH sensor does not end during sen-
sor cooking condition. (Oven does
not shut off after a cup of water is
boiling by sensor cooking.)
Oven stops at 16 sec. after starting.
OFF
CONDITION
PROBLEM
CONDITION
SHORT IN POWER CORD
SHORT OR OPENED WIRING
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
THERMAL CUT-OUT
SECONDARY INTERLOCK SYSTEM
PRIMARY INTERLOCK SWITCH
MONITOR SWITCH
MONITOR FUSE
OVEN LAMP
COOLING FAN MOTOR
TURNTABLE MOTOR
CONTROL UNIT
WRONG OPERATION
LOW VOLTAGE
DIRTY OVEN CAVITY
KEY UNIT
RELAY (RY1)
COMPU DEFROST
FOIL PATTERN ON PWB.
AH SENSOR
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
RE RE ABCDEFFGH RERE CK I CK CKCK JKLMN
COOKING
CONDITION
CK = Check / RE = Replace
SENSOR
COOKING
CONDITION

12
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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 the 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 85 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.
AMAGNETRON ASSEMBLY TEST
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 the high voltage capacitor.
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
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (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
a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through
the water until the temperature stabilizes. Record the temperature of the water.
2. Place the cup of water in the oven. Operate oven at POWER P-HI(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.Thenormalresultshouldbe30.7
to57.1˚F(17.1to31.7˚C)riseintemperature.Ifthewatertemperaturesareaccuratelymeasuredand
tested for the required time period the test results will indicate if the magnetron tube has low power
output (low rise in water temperature) which would extend cooking time or high power output (high
risein water temperature)which would reducecookingtime. Because cookingtime can beadjusted
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.

13
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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 the high voltage capacitor.
4. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads
and check for short or open between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate
continuity for a short time and should indicate an open circuit once the capacitor is charged. If the
above is not the case, check the capacitor with an ohmmeter 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
EOVEN THERMAL CUT-OUT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge the high voltage capacitor, wait for 60 seconds.
4. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 257˚F(125˚C).
An open thermal cut-out indicates overheating of the oven, exchange the oven thermal cut-out and
checkinsideofovencavityandforimpropersettingofcookingtimeoroperationofcontrolunit.Check
forrestrictedairflowthroughtheventholesoftheovencavity,especiallythecoolingfanandairguide.
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.
MAGNETRON THERMAL CUT-OUT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge the high voltage capacitor, wait for 60 seconds.
4. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the magnetron reaches approximately 257˚F(125˚C). An open thermal cut-out
indicatesoverheatingofthemagnetron.Checkforrestrictedairflowtothemagnetron,especiallythe
cooling fan air guide.
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 the 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:Besureto use anohmmeterthatwill supply aforwardbiasvoltage of more than6.3volts.
(HIGHVOLTAGESAREPRESENTATTHEHIGHVOLTAGE TERMINAL, SO DONOTATTEMPTTO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)

14
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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. To discharge the high voltage capacitor, wait for 60 seconds.
4. Before performing this test, make sure that the primary interlock switch and the secondary interlock
relayareoperatingproperly,accordingtotheaboveSwitchTestProcedure.Disconnectthewirelead
fromthe monitor switch(COM)terminal.Check the monitorswitchoperationby using theohmmeter
asfollows.Whenthedoorisopen,themetershouldindicateaclosedcircuit.Whenthemonitorswitch
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.
CAUTION: IFTHETHERMALCUT-OUTINDICATESANOPENCIRCUITATROOMTEMPERATURE,
REPLACE THERMAL CUT-OUT.
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge the high voltage capacitor, wait for 60 seconds.
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.
SECONDARY INTERLOCK SYSTEM TEST
DOOR SENSING SWITCH
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge the high voltage capacitor, wait for 60 seconds.
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: If the door sensing switch contacts fail in the open position and the door is closed, the cooling
fan, turntable and oven light will be activated by RY1.
SECONDARY INTERLOCK RELAY (RY2)
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. To discharge the high voltage capacitor, wait for 60 seconds.
4. Disconnect two (2) wire leads from the male tab terminals of the Secondary interlock relay. Check
the state of the relay contacts using a ohmmeter. The relay contacts should be open. If the relay
contacts 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.
FPRIMARY INTERLOCK SWITCH TEST
GMONITOR SWITCH TEST

15
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HBLOWN MONITOR FUSE TEST
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. To discharge the high voltage capacitor, wait for 60 seconds.
4. If the monitor fuse is blown when the door is opened, check the secondary interlock relay, primary
interlockswitchandmonitorswitchaccordingtothe"TESTPROCEDURE"forthoseswitchesbefore
replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE SECONDARY INTER-
LOCK RELAY, PRIMARY INTERLOCK SWITCH, DOOR SENSING SWITCH AND MONI-
TOR SWITCH FOR PROPER OPERATION.
If the monitor fuse is blown by improper switch operation, the monitor fuse and monitor switch must
be replaced with "monitor fuse and monitor switch assembly" part number FFS-BA023WRK0, even
ifthemonitor switch operates normally.Themonitorfuseandmonitorswitch assembly is comprised
of a 20 ampere fuse and 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.
The control unit consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike
conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and
ohmmeter. In this service manual, the control panel unit is divided into three units, CPU Unit, Key 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) To discharge high voltage capacitor, wait for 60 seconds.
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.
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.
ICONTROL UNIT TEST
actuatoris pushed byascrewdriver through thelowerlatch hole on thefrontplate of theovencavity
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. 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.
Primary
Interlock Switch
Monitor Switch
Screw Driver
Ohmmeter
RED WHT

16
R-370EK
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If the Key unit is defective, replace the key unit.
2. Control Unit
The following symptoms indicate a defective control unit. Before replacing the control unit, perform
the 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 and/or replacement is completed,
1) Disconnect the power supply cord, and then remove outer case.
2) To discharge the high voltage capacitor, wait for 60 seconds.
3) Re-install all removed parts.
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
JKEY UNIT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. To discharge the high voltage capacitor, wait for 60 seconds.
3. If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable
ismakinggoodcontact,verifythatthedoorsensingswitch(stopswitch)operatesproperly;thatisthe
contacts are closed when the door is closed and open when the door is open. If the door sensing
switch (stop switch) is good, disconnect the flat ribbon cable that connects the key unit to the control
unitandmake sure the doorsensingswitchisclosed (either close thedoororshortthedoor sensing
switch connecter). Use the Key unit matrix indicated on the control panel schematic and place a
jumperwirebetweenthepinsthatcorrespondtotheSTOP/CLEARpadmakingmomentarycontact.
If the control unit responds by clearing with a beep the key unit is faulty and must be replaced. If the
control unit does not respond, it is faulty and must be replaced. If a specific pad does not respond,
the above method may be used (after clearing the control unit) to determine if the control unit or key
pad is at fault.
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.
G 8
G 7 G 6 G 5 G 4 G 3 G 2 G 1
G 9G10G11
8
1
3
2
6
7
4
5
9
0
Rice
Power
Level
Fresh
Vegetables
Frozen
Vegetables
Kitchen Timer
Clock
Rolls &
Muffins
Frozen
Entrees
Fish
Seafood STOP
Clear
Compu
Defrost Baked
Potatoes
Popcorn
Chicken
Breast
Ground
Meat Reheat
Sensor
Custom
Help
Beverage
Minute Plus
START

17
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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 " COMPU DEFROST " pad once.
(3) Touch " COMPU DEFROST " pad twice.
(4) Touch the Number pad " 5 " and then touch the " START " pad.
(5) The oven is in Compu Defrost cooking condition.
(6) The oven will operate as follows.
MENU 1ST STAGE 2ND STAGE
Steaks/Chops LEVEL TIME LEVEL TIME
0.5lb 60% 40sec. 40% 40sec.
(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. To discharge the high voltage capacitor, wait for 60 seconds.
4. Disconnect the leads to the primary of the power transformer.
5. Ensurethattheseleadsremainisolatedfromothercomponentsandovenchassisbyusinginsulation
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......... Checkdiodewhichisconnectedtotherelaycoil.Ifdiodeisgood,
control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 Approx. 24.0V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 Approx. 23.0V D.C. Power transformer
8. Disconnect the power supply cord, and then remove outer case.
9. Open the door and block it open.
10.To discharge the high voltage capacitor. wait for 60 seconds.
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
MFOIL 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.
1. Foil pattern check and repairs.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) To discharge the high voltage capacitor, wait for 60 seconds.
4) Follow the troubleshooting guide given below for repair.
KRELAY TEST

18
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TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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) Makeavisualinspectionofthevaristor.Check
for burned damage and examine the
transformer with a tester for the presence of
layer short-circuit (check the primary coil
resistance which is approximately 212Ω±
10%). If any abnormal condition is detected,
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. Followthetroubleshootingguide givenbelow,iftheindicatordoes notlightupafterabovecheck and
repairs are finished.
1) Disconnect the power supply cord, and then remove outer case.
2) Open the door and block it open.
3) To discharge the high voltage capacitor, wait for 60 seconds.
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) Follow the troubleshooting guide given below for repair.
STEPS OCCURRENCE CAUSE OR CORRECTION
The rated AC voltage is not present between
1 the normal open terminal of the relay RY1 and Check supply voltage and oven power cord.
the normal open terminal of the relay RY2.
2The 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) To discharge the high voltage capacitor, wait for 60 seconds.
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.
NAH SENSOR TEST
Checking the initial sensor cooking condition
WARNING : The oven should be fully assembled before following procedure.
(1) The oven should be plugged in at least two minutes before sensor cooking.
(2) Room temperature should not exceed 95˚F (35˚C).
(3) The unit should not be installed in any area where heat and steam are generated. The unit should
not be installed, for example, next to a conventional surface unit. Refer to the “INSTALLATION
INSTRUCTIONS” of the operation manual.
(4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To
permit adequate ventilation, be sure to install so as not to block these vents. There should be some
space for air circulation.
CN - A ad
cb
(J1)
P
1
RY1
RY2
T1
VRS1
12