Sharp R-21HT - Commercial Microwave Oven User manual

R-21HT
R-21HV
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..)
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 ..............................................................................................................................9
TEST PROCEDURE............................................................................................................................................10
TOUCH CONTROL PANEL .................................................................................................................................18
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................25
PICTORIAL DIAGRAM ........................................................................................................................................32
CONTROL PANEL CIRCUIT ..............................................................................................................................33
PRINTED WIRING BOARD .................................................................................................................................35
PARTS LIST ........................................................................................................................................................36
PACKING AND ACCESSORIES .........................................................................................................................41
S7814R21HTP//
R-21HT
R-21HV
LIGHT DUTY
COMMERCIAL
MICROWAVE OVENS
MODEL
SERVICEMANUAL
SHARP CORPORATION This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-21HV
1000W/ R-21HV
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X2
CHECK

R-21HT
R-21HV
PRECAUTIONSTO BE OBSERVED BEFORE AND
DURING SERVICINGTO AVOID POSSIBLE
EXPOSURETO 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 oven 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 the 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.

R-21HT
R-21HV
1
WARNINGTO 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 (thatis the connectinglead ofthe high-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Whenever troubleshooting is performed the power supply
mustbedisconnected.Itmayin,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. Reconnectthe power supplycord afterthe outer caseis
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 supplycord afterthe outer caseis
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 two minutes has elapsed (timer at zero)
carefully check that the water is now hot. If the water
remainscoldcarryoutBeforeServicingprocedureandre-
examine the connections to the component being tested.
When all service work is completed and the oven is fully
assembled,themicrowavepoweroutputshouldbechecked
and microwave leakage test should be carried out.
Don't Touch !
Danger High Voltage

R-21HT
R-21HV
2
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
bya purchaser, andthereafter (through theuseful life ofthe oven), 5mW/cm2at anypoint5cm ormorefrom theexternal
surface of the oven.
2) Safety interlock switches Primary interlock relay and door sensing switch shall prevent microwave radiation emission in
excess of the requirement as above mentioned, secondary interlock switch shall prevent microwave radiation emission
in excess of 5 mW/cm2at 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:
Surveyinstruments that complywith the requirementfor instrumentation as prescribed bythe performance standardfor
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 thisstandard load inthe oven is important notonly to protectthe oven, butalso to insure 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,
and that the secondary interlock switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.

R-21HT
R-21HV
3
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
LIGHT DUTY
COMMERCIAL
MICROWAVE OVEN
R-21HT/ R-21HV
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVENS, R-21HT, R-21HV.
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.
Alltheparts marked “∆”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

R-21HT
R-21HV
4
ITEM DESCRIPTION
Power Requirements 120 Volts
14 Amperes
60 Hertz / Single phase, 3 wire grounded
Power Output 1000 watts (IEC 705 Test Procedure)
Operating frequency of 2450MHz
Case Dimensions Width 20-1/2" (520mm)
Height 12-1/8" (309mm)
Depth 16" (406mm)
Cooking Cavity Dimensions Width 13-7/8" (353mm)
(1.0 Cubic Feet ) Height 8-1/8" (207mm)
Depth 14-5/8" (370mm)
Control Complement Touch Control System
Timer (0 - 99 min. 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
P-HI..................................................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
DOUBLE QUANTITY pad
EXPRESS DEFROST pad
Ten number pads
SELECTATIME pad
STOP/CLEAR pad
SELECATAPOWER pad [R-21HT only]
START pad, SET pad
CHECK pad, SIGNAL pad
Oven Cavity Light Yes
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J, NSF certified
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.

R-21HT
R-21HV
5
3-Pronged Plug Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
OVEN DIAGRAM
1. Back splash cover
2. Side splash cover
3. Oven light
4. Ceramic shelf
5. Control panel
6. Cavity face plate
7. Door latch openings
8. Door latches
9. Door hinges
10.Doorsealsandsealingsurfaces
11.Door handle
12.Oven door with see-through
window
13.Air ventilation cover and openings
,k.Power supply cord
15.Air intake openings
16.Outer case cabinet
Electrical Requirements
The electrical requirements are a 120 volt 60 Hz, AC only,
15 amp. or more protected electrical supply. It is recommended that a
separatecircuitservingonlythisappliance be provided.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 contact a qualified
electricianandhaveitreplacedwith a properlygrounded 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.orhigherratedcord.Donotdrapeoveracountertoportablewhere
it can be pulled on by children or tripped over accidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM
THIS PLUG.
114 13 912
11
76 5
15 16
10
3 2
4
8
1. Digital Readout
2. DOUBLE QUANTITY pad
3. EXPRESS DEFROST pad
4. Ten number pads for time
and memory programming
5. SELECTATIME pad
6. STOP/CLEAR pad; touch to
stop operation of oven and
clear remaining heating time
7. SELECATAPOWER pad for
setting variable power level
(R-21HT only)
8. STARTpad;touchtooperate
ovenafter door isclosed and
time is set
9. SET pad for setting memory
10.CHECK pad for checking
memory
11.SIGNALpadforsettingsignal
sound
DEF ON NO. X2 CHECK DEF ON NO. X2 CHECK
11
33
4
6
8
11
4
6
8
11
2
5
7
9
10
2
5
9
10
TOUCH CONTROL PANEL
R-21HT R-21HV

R-21HT
R-21HV
6
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
Thefollowingisadescriptionofcomponentfunctionsduring
oven operation.
OFF CONDITION
Closingthedooractivatesdoorsensingswitchandsecond-
ary 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 . .
COOKING CONDITION
Program desired cooking time by touching SELECTATIME
pad and the NUMBER pads. 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-2 power transformer
RY-3 oven lamp/antenna motor/fan motor
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.2 volts
A.C. output on the filament winding, and approximately
2150 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, monitor
switch,doorsensingswitch, secondary interlockswitch,
relay (RY3) and primary interlock relay (RY2) are
activated with the following results. The circuits to the
antenna motor, the cooling fan motor, and the high
voltage components are de-energized, the oven lamp
remains on, and the digital read-out displays the time
still remaining in the cook cycle when the door was
opened.
7. Themonitorswitchelectrically monitorstheoperationof
the secondary interlock switch and control relay (RY3)
and is mechanically associated with the door so that it
will function in the following sequence.
(1) Whenthedooropensfromtheclosedposition,theprimary
interlockrelay(RY2)andsecondaryinterlockswitchopen
their contacts. And contacts of the relay (RY3) remains
closed. Then the monitor switch contacts close.
(2)When the door is closed from the open position, the
monitor switch contacts open first. Then the contacts of
the secondary interlock switch and door sensing switch
close and contacts of the relay (RY3) open.
Ifthesecondaryinterlock switchandprimaryinterlock relay
(RY2)failwiththecontactsclosedwhenthedoorisopened,
the closing of the monitor switch contacts will form a short
circuitthroughthemonitorfuse,secondaryinterlockswitch,
relay (RY3) and primary interlock relay (RY2), causing the
monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING (R-21HT only)
When Variable Cooking Power is programmed, the 120
voltsA.C.issuppliedtothepowertransformerintermittently
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: 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.

R-21HT
R-21HV
7
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. SELECTATIME PAD TOUCHED.
3. COOKING TIME ENTERED.
4. START PAD TOUCHED.
Figure O-2 Oven Schematic-Microwave cooking Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. . APPEARED.
NOTE: Indicates components with potential above 250 V.
Figure O-1 Oven Schematic-OFF Condition
OL FM AM
OVEN 
LAMP FAN  MOTOR ANTENNA  MOTOR
AC120V
60 Hz
MONITOR
FUSE 20A
POWER
TRANSFORMER
CAPACITOR
0.94 µF
2400V
DOOR SENSING
SWITCH
SECONDARY
INTERLOCK SWITCH
CONTROL UNIT
THERMAL
CUT-OUT
125˚C (OVEN)
THERMAL
CUT-OUT
145˚C (MAG.)
PRIMARY INTERLOCK RELAY
CONTROL RELAY
MONITOR SWITCH
MAGNETRON
RECTIFIER
RY3 RY2
A3 A7
B1 B2
OL FM AM
OVEN 
LAMP FAN  MOTOR ANTENNA  MOTOR
AC120V
60 Hz
MONITOR
FUSE 20A
POWER
TRANSFORMER
CAPACITOR
0.94 µF
2400V
DOOR SENSING
SWITCH
SECONDARY
INTERLOCK SWITCH
CONTROL UNIT
THERMAL
CUT-OUT
125˚C (OVEN)
THERMAL
CUT-OUT
145˚C (MAG.)
PRIMARY INTERLOCK RELAY
CONTROL RELAY
MONITOR SWITCH
MAGNETRON
RECTIFIER
RY3 RY2
A3 A7
B1 B2

R-21HT
R-21HV
8
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by grasping the door handle, refer to
Figure D-1.
When the door handle is grasped, the handle lever is
pulled. And then the upper and lower latch heads are
moved upward by the handle lever, and they are released
from the latch hook. Now the door will open.
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the upper
positionofthelatchhookand the doorsensing switchinthe
primaryinterlock systemis mountedin thelower positionof
the latch hook. The secondary interlock switch is activated
by the latch switch lever A. The latch switch lever A is
activated by the upper latch head. The door sensing switch
is activated by the latch switch lever C. The latch switch
lever C is activated by the lower latch head. 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 primaryinterlock systemconsists of thedoor
sensing switch and primary interlock relay located on the
control circuit board.
MONITOR SWITCH
Themonitorswitchisactivated(thecontactsopened)bythe
latch switch lever B on the latch hook while the door is
closed. The latch switch lever B is activated by the lower
latch head. The switch is intended to render the oven
inoperative,bymeansofblowingthemonitorfuse,whenthe
contactsoftheprimaryinterlockrelay(RY2)andsecondary
interlock switch fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contacts
close (to the ON condition) due to their being normally
closed.Atthistimetheprimaryinterlockrelay(RY2)and
secondary interlock switch are in the OFF condition
(contactsopen)duetotheirbeingnormallyopencontact
switches.
2. Asthe door goes toaclosedposition,themonitorswitch
contacts are first opened and then the door sensing
switchandthesecondaryinterlockswitchcontactsclose.
(On opening the door, each of these switches operate
inversely.)
Latch Hook
Latch Switch
Lever A
Latch Switch
Lever B
Latch Switch
Lever C
Latch Head
Latch Head
Handle
Lever
Door
Handle
Latch
Lever Secondary
Interlock
Switch
Monitor
Switch
Door
Sensing
Switch
3. If the door is opened, and the primary interlock relay
(RY2) and secondary interlock switch contacts fail to
open,themonitorfuseblowssimultaneouslywithclosing
of the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAY (RY2), RE-
LAY (RY3) SECONDARY 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.
ANTENNA MOTOR
The antenna motor rotates the stirrer antenna located on
the bottom of the oven cavity, so that the food on the
ceramic shelf is cooked evenly during cooking. The an-
tenna motor may turn in either 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 food. It is then
exhausted through the exhausting air vents at the oven
cavity.
MONITOR FUSE
1. The monitor fuse blows when the contacts (COM-NO)
of the primary interlock relay (RY2) and secondary
interlock switch remain closed with the oven door open
and when 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.
THERMAL CUT-OUT 145˚C (MAGNETRON)
This thermal cut-out protects the magnetron against over-
heating. If the temperature goes up higher than 293˚F
(145˚C) because the fan motor is interrupted or the ventila-
tion openings are blocked, the thermal cut-out will open
and line voltages to the high voltage transformer will be cut
off and the operation of the magnetron will be stopped.
The thermal cut-out will not resume.
THERMAL CUT-OUT 125˚C (OVEN)
The thermal cut-out located on the top of the oven cavity is
designed to prevent damage to the oven if the food in the
oven catches fire due to over heating produced by im-
proper setting of the cooking time or failure of control unit.
Under normal operation, the oven thermal cut-out remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the oven thermal cut-out
will open at 257˚F(125˚C) causing the oven to shut down.
The thermal cut-out will not resume.

R-21HT
R-21HV
9
TROUBLESHOOTING GUIDE
Nevertouch anypart inthecircuitwithyourhandor anuninsulated toolwhile thepower supplyis connected.
Whentroubleshootingthemicrowaveoven, it ishelpfultofollowthe Sequence ofOperation inperformingthechecks.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 (RY3),
primary interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the
monitor fuse. If monitor fuse is replaced, the monitor switch must also be replaced. Use part FFS-
BA015WRK0 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. Ensurethattheleadsremain isolated fromothercomponentsandoven chassis byusing 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.

R-21HT
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10
TEST PROCEDURE
CONDITION PROBLEM
POSSIBLE CASE
AND 
DEFECTIVE PARTS
Home fuse or circuit breaker blows when
power cord is plugged into wall outlet.
Monitor fuse blows when power cord is
plugged into wall receptacle.
. does not appear in display when
power cord is first plugged into wall outlet.
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 antenna
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 extremely
uneven heating is produced in oven load
(food).
Oven does not cook properly when
programmed for Cooking Power 5 mode.
(Operates properly on Cooking Power 10
(HIGH) mode.)
"EE9" Maximum time is exceeded.
OFF
CONDITION
COOKING
CONDITION
ERROR MODE
MAGNETRON POWER TRANSFORMER H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE CAPACITOR THERMAL CUT-OUT SECONDARY INTERLOCK SWITCH PRIMARY INTERLOCK SYSTEM MONITOR SWITCH MONITOR FUSE TOUCH CONTROL PANEL KEY UNIT EXCEED MAX. HEATING TIME RELAY (RY3) FOIL PATTERN ON P.W.B. LOW VOLTAGE WRONG OPERATION DIRTY OVEN CAVITY SHORTED IN POWER CORD OVEN LAMP OR SOCKET COOLING FAN MOTOR ANTENNA MOTOR
SHORT OR OPENED WIRING
A B C D E F F G H I J K L CK RE RE RERE RE CK CK CK
CK = Check / RE = Replace
A MAGNETRON 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 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).

R-21HT
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11
B POWER 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 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.
(HIGHVOLTAGESAREPRESENT ATTHEHIGHVOLTAGE TERMINAL, SODONOTATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
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 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.Thenormalresultshouldbe34.7
to64.6˚F(19.3to35.9˚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
rise 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.
C HIGH 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,

R-21HT
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12
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. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads
and check for a 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.
D HIGH VOLTAGE CAPACITOR TEST
E THERMAL CUT-OUT TEST 125˚C (OVEN)
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. 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).
Anopen thermalcut-outindicates overheatingof the oven,exchange the thermalcut-out and check
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.
THERMAL CUT-OUT TEST 145˚C (MAGNETRON)
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. A continuity check across the thermal cut-out terminals should indicate a closed circuit. If the
temperature of the magnetron reaches approximately 293˚F(145˚C), the thermal cut-out opens. An
open thermal cut-out indicates overheating of the magnetron. Check for restricted air flow to the
magnetron, especially the cooling fan 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.
CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERA-
TURE, REPLACE THERMAL CUT-OUT.
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 to use an ohmmeter that will supplya forwardbias voltage ofmore than6.3 volts.
FSECONDARY INTERLOCK SWITCH TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.

R-21HT
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13
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. Before performing this test, make sure that the secondary interlock switch and the primary interlock
relayareoperatingproperly,accordingtotheaboveSwitchTestProcedure.Disconnectthewirelead
fromthe monitor switch(COM) terminal. Checkthe monitor switch operation byusing the ohmmeter
asfollows.Whenthedoorisopen,themetershouldindicateaclosedcircuit.Whenthemonitorswitch
actuatoris pushed bya screw driverthrough the lower latch holeon the frontplate of theoven 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. 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.
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 secondary 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.
PRIMARY 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. 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: If the door sensing switch contacts fail in the open position and the door is closed, the cooling
fan, antenna and oven light will be activated by RY3.
PRIMARY INTERLOCK RELAY (RY1)
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 two (2) wire leads from the male tab terminals of the Primary Interlock Relay. Check the
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.
G MONITOR SWITCH TEST
SCREW 
DRIVER
MONITOR 
SWITCH
OHMMETER
WHT/ WHT

R-21HT
R-21HV
14
H BLOWN 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. Discharge high voltage capacitor.
4. If the monitor fuse is blown when the door is opened, check the primary interlock relay, secondary
interlockswitchandmonitorswitchaccordingtothe"TESTPROCEDURE"forthoseswitchesbefore
replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK
RELAY,SECONDARYINTERLOCKSWITCH,DOORSENSINGSWITCHANDMONITOR
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-BA015WRK0, even
ifthe monitorswitch operatesnormally. Themonitor fuseand monitor switch 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.
I TOUCH CONTROL PANEL ASSEMBLY 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
and ohmmeter.
In this service manual, the touch control panel assembly is divided into two units, Control Unit and Key
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.
6) After that procedure, re-connect the power supply cord.
1. Key Unit.
NOTE ;
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) Check key unit ribbon connection before replacement.
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.
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.
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).

R-21HT
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15
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
7) Reconnect the power supply cord after the outer case is installed.
8) Run the oven and check all functions.
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 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.
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. If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable
is making good contact, verify that the door sensing switch (stop switch) operates properly; that is
the 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 unit and make sure the door sensing switch is closed (either close the door or short the
door sensing switch connecter). Use the Key unit matrix indicated on the control panel schematic
and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making
momentary contact. 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.
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.
R-21HT R-21HV
J KEY UNIT TEST
5
6
3
4
1
2
7
8
9
0
SELECTA
TIME STOP/ CLEAR
START SET
CHECK
SIGNAL
DOUBLE
QUANTITY
EXPRESS
DEFROST
G12
G11
G10
G 9
G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8
5
6
3
4
1
11131519
12141620
17
18
2
7
8
9
0
SELECTA
TIME
SELECTA
POWER
STOP/
CLEAR
START SET
CHECK
SIGNAL
DOUBLE
QUANTITY
EXPRESS
DEFROST
G12
G11
G10
G 9
G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8

R-21HT
R-21HV
16
K RELAY 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 high voltage capacitor.
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 Pin Numbers. 3 and 7 of the connector (A) 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
RY2 Approx. 12.0V D.C. Power transformer
RY3 Approx. 12.0V D.C. Oven lamp / Antenna motor / Cooling fan motor
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.
L 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.
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) 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) Make a visual inspection of the varistor.
Checkforburneddamageandexamine
the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance which is
approximately 270Ω±10%). If any
abnormalconditionisdetected,replace
the defective parts.
(17)
a
b
cd
(CT1)
(J1)
(J7)
(TB1)
12
P
VRS1
(VRS2)
POWER
7

R-21HT
R-21HV
17
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. Follow the troubleshooting guide given below, if indicator does not light up after above check and
repairs 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
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
1The rated AC voltage is not present to power Check supply voltage and oven power cord.
terminal of CPU connector (CN-A).
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) 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.
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST

R-21HT
R-21HV
18
This model has 20 Memory pads.
When the oven is shipped, Memory pad 1 to 10 are
set as follows: fig.1.
Memory No. Cook Time Output Power
1 10 sec. 100%
2 20 sec. 100%
3 30 sec. 100%
4 45 sec. 100%
5 1 min. 100%
6 1 min. 15 sec. 100%
7 1 min. 30 sec. 100%
8 2 min. 100%
9 2 min. 30 sec. 100%
0 3 min. 100%
(fig. 1)
This model has a double quantity pad. When the oven
is shipped, Magnification "1.8" is preset in the double
quantity pad.
This model has an express defrost pad. When the
oven is shipped, express defrost is set as follows:
fig.2.
1 STAGE 2 STAGE 3 STAGE
FORMULA P = 0.2T P = 0.15T P = 0.65T
POWER 60 % 40 % 20 %
T : Total cooling time (fig. 2)
When 1/2 total cooking time is passed, the signal will
sound and "CHECK" indicator will flash.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units
as shown in the touch control panel circuit.
(1) Control Unit
(2) Key Unit
The principal functions of these units and the signals
communicated among them are explained below.
1. Control Unit
Signal of key touch and oven function control are all
processed by one microcomputer.
1) Power Supply Circuit
This circuit changes output voltage at the secondary
side of the low voltage (T1) transformer to voltages
required at each part by full wave rectifying circuit,
constant voltage circuit, etc..
2) ACL Circuit
This is an Auto-clear Circuit, i.e., a reset circuit, which
enables IC1 to be activated from initial state.
3) Power SYNC Signal Generating Circuit
This is a circuit for generating power SYNC signal by
virtue of the secondary side output of transformer T1.
This signal is used for a basic frequency to time
processing and so on.
4) Clock Circuit
This is a circuit for controlling clock frequency required
for operating IC1.
5) IC1 (Main Processor)
This is a one-chip microcomputer, responsible for
controlling the entire control unit.
6) IC2 (Memory Processor)
This is a memory IC, responsible for memory function.
7) IC3
This is a IC for driving light emitting diode.
8) Display Circuit
This is a circuit for driving light emitting diode by IC1
output.
9) Key Input Circuit
This is a circuit for transmitting key input information
to IC1.
10) Sound-body Driving Circuit
This is a circuit for driving sound body by IC1 output.
11) Relay Driving Circuit
This is a circuit for driving output relay by IC1 output.
12) Door Sensing Switch Circuit
This is a circuit for driving IC1 to detect door opening/
closing.
2. Key Unit
The key unit is composed of a matrix circuit in which
when a key it touched, one of signals P30--P34
generated by the LSI, is passed through the key and
returned to the LSI as one of signals P24--P27.