SERVICE MANUAL
S8509R22GTF//
COMMERCIAL
MICROWAVE OVEN
R-22GT-F
R-22GV-F
MODELS
R-22GT-F
R-22GV-F
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R-22GT-F
TABLE OF CONTENTS
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICE TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ...................INSIDE FRONT COVER
BEFORE SERVICING ......................................................................................................INSIDE FRONT COVER
WARNING TO SERVICE PERSONEL .................................................................................................................. 1
MICROWAVE MEASUREMENT PROCEDURE ................................................................................................... 2
FOREWORD .......................................................................................................................................................... 3
PRODUCT SPECIFICATIONS .............................................................................................................................. 4
GENERAL INFORMATION................................................................................................................................... 4
OPERATION .......................................................................................................................................................... 6
TROUBLE SHOOTING GUIDE/ TEST PROCEDURE ........................................................................................ 10
TOUCH CONTROL PANEL ................................................................................................................................. 20
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................ 30
PICTORIAL DIAGRAM ........................................................................................................................................ 37
CONTROL PANEL CIRCUIT ...............................................................................................................................38
PRINTED WIRING BOARD .................................................................................................................................39
PARTS LIST ........................................................................................................................................................ 40
PACKING AND ACCESSORIES ......................................................................................................................... 43
In the interest of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
WARNING TO SERVICE PERSONNEL: Microwave ovens contain 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 Rectifier Assembly, High Voltage Harness etc..)
Page
SHARP CORPORATION
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-22GT-F
R-22GV-F
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 the Food and Drug Administration's
Center for Devices and Radiological Health immediately.
Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found
with emissions in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit
until the oven has been brought into compliance.
WARNING TO SERVICE PERSONNEL
Don't Touch !
Danger High Voltage
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with
following parts
fatal, electrical shock.
(Example)
High Voltage Capacitor, High Voltage Power Trans-
former, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
may result in a severe, possibly
R-22GT-F
R-22GV-F
Before Servicing
1. Disconnect the power supply cord, and then remove
outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
WARNING: RISK OF ELECTRIC SHOCK.
DISCHARGE THE TWO HIGH
VOLTAGE CAPACITORS BEFORE
SERVICING.
The high-voltage capacitors remain charged about 60
seconds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the highvoltage capacitors (that are the connecting lead of the
high-voltage rectifiers) against the chassis with the use of
an insulated screwdriver.
Whenever troubleshooting is performed the power supply
must be disconnected. It may, in some cases, be necessary
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 two high voltage capacitors.
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 two high voltage capacitors.
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.
After repairing
1. Reconnect all leads removed from components during
testing.
2. Reinstall the outer case (cabinet).
3. Reconnect the power supply cord after the outer 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 two minutes has elapsed (timer at zero)
carefully check that the water is now hot. If the water
remains cold carry out Before Servicing procedure and reexamine the connections to the component being tested.
When all service work is completed and the oven is fully
assembled, the microwave power output should be checked
and microwave leakage test should be carried out.
1
R-22GT-F
R-22GV-F
MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
should not exceed 1mW/cm2 at any point 5cm or more from the external surface of the oven, measured prior to acquisition
by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm2 at any point 5cm or more from the external
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/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.
The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage
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) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.
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) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal
has been breached (eg., around the switches, indicator, and vents).
While testing for leakage around the door pull the door away from the front of the oven as far as is permitted by the closed
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 primary interlock relay and secondary interlock switch do turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
2
SERVICE MANUAL
COMMERCIAL
MICROWAVE OVEN
PRODUCT DESCRIPTION
R-22GT-F
R-22GV-F
R-22GT-F/ R-22GV-F
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVEN, R-22GT-F and R-22GV-F.
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
Certain initial parts are intentionally not grounded and present
a risk of electrical shock only during servicing. Service
personnel - Do not contact the following parts while the
appliance is energized;
High Voltage Capacitor, Power Transformer, Magnetron, High
Voltage Rectifier Assembly, High Voltage Harness;
If provided, Vent Hood, Fan assembly, Cooling Fan Motor.
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST
All the parts marked “*” on parts list are used at voltages more than
250V.
Removal of the outer wrap gives access to voltage above 250V.
All the parts marked “∆” on parts list may cause undue microwave
exposure, by themselves, or when they are damaged, loosened
or removed.
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
3
R-22GT-F
Receptacle Box Cover
3-Pronged plug
(NEMA 5-20)
3-Pronged, Receptacle
(NEMA 5-20)
R-22GV-F
SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts 2.0 kW
Approx. 17.7 A
60 Hertz / Single phase, 3 wire grounded
Power Output 1200 watts (IEC Test Procedure) Operating frequency of 2450MHz
Case Dimensions Width 20-1/8" (510mm) Height 13-1/4" (335mm) Depth 18-1/2" (470mm)
Cooking Cavity Dimensions Width 13" (330mm) Height 7-1/8" (180mm) Depth 13" (330mm)
Control Complement Touch Control System
Digital Display
10 Number Pads
STOP/CLEAR pad
START pad
SELECTAPOWER pad (Power level: 0 to 100%, for R-22GT-F)
SELECTATIME pad
DOUBLE QUANTITY pad
EXPRESS DEFROST pad
Memory SET pad
Memory CHECK pad
SIGNAL pad
Weight Approx. 60 lbs/ 27 kg
Safety Standard UL/ C-UL/ FCC
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
NSF, Health Canada
GENERAL INFORMATION
GROUNDING INSTRUCTIONS
This appliance must be grounded. In the event of an electrical short circuit, grounding reduces the risk of electric shock by
providing an escape wire for the electric current. This appliance is equipped with a cord having a grounding wire with a
grounding plug. The plug must be plugged into an outlet that is properly installed and grounded.
WARNING: Improper use of the grounding plug can result in a risk of electric shock. The electrical requirements are 120
Volt, 60 Hz, AC only, and 20 Amp or more fused electrical supply. It is recommended that a separate circuit
serving only this appliance be provided. When installing this appliance, observe all applicable codes and
ordinances. If it is necessary to use an extension cord, use only a 3-wire extension cord that has a 3-blade
grounding plug and a 3-slot receptacle that will accept the plug on the appliance. The marked rating of the
extension cord should be AC 120 Volt 20 Amp.
4
OVEN DIAGRAM
R-22GT-F
R-22GV-F
10
9
12
11
1. Touch control panel
2. Door latch openings
3. Ceramic shelf
4. Splash cover
5. Oven light
6. Air intake filter
7. Air intake openings
8. Door seals and sealing surfaces
9. Door hinges
10.Oven door with see-through window
11.Door latches
12.Door handle
13.Service window for replacing the oven
light bulb.
14.Ventilation openings
15.Power supply cord
16.Mounting plate
17.Screw for mouning plate
Control Panel
18.DOUBLE QUANTITY pad
19.EXPRESS DEFROST pad
20.Ten number pads for time and memory
programming
21.SELECTATIME pad
22.STOP/CLEAR pad; touch to stop
operation of oven and clear remaining
heating time
23.SELECTAPOWER pad for setting
variable power level
24.START pad; touch to operate oven after
door is closed and time is set
25.SET pad for setting memory
26.CHECK pad for checking memory
27.SIGNAL pad for setting signal sound
5
3
4
2
16
17
1
13
15
14
678
18
DEFONNO.X2CHECK
DOUBLE
QUANTITY
EXPRESS
DEFROST
1
2
3
4
5
19
20
18
DEFONNO.X2CHECK
DOUBLE
QUANTITY
EXPRESS
DEFROST
11
1
12
2
13
3
14
4
15
5
16
6
19
20
6
17
7
7
18
8
8
9
19
9
20
0
0
21
25
SELECTA
STOP
TIME
CLEAR
SET CHECK SIGNAL
26
R-22GV-F R-22GT-F
START
22
24
27
21
23
25
SELECTATIME STOP/CLEAR
SELECTAPOWER
SET CHECK SIGNAL
START
26
22
24
27
5
R-22GT-F
R-22GV-F
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions during
oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and
secondary interlock switches (1), (2). (In this condition, the
monitor switches (1) & (2) contacts are opened.) When the
oven is plugged in, and the rated voltage is supplied to the
control unit, (figure O-1), the display will show " . ".
IDLE CONDITION
When the door is opened, the contacts of the door sensing
switch open, initiating the following:
1. A signal is input to the control unit energizing the coil of
shut-off relay (RY-1).
2. The shut-off relay (RY-1) contacts close completing
circuits to turn on the oven lamp, blower motor and stirrer
motors.
3. If the door remains open, 60 seconds later the control
unit de-energizes shut-off relay (RY-1) turning off the
oven lamp, blower motor and stirrer motors.
When the door is closed, the door sensing switch contacts
close. With the closing of the door sensing switch contacts,
an additional circuit is provided which will permit the operation of the oven when one of the touch pads is depressed.
Since the control is enabled through the door sensing
switch, the door must be closed before the touch pads will
be effective. When the door is closed, a full 60 second IDLE
condition is always provided for selecting and pressing the
desired touch pads. A 60 second IDLE condition will also
follow the end of each cook cycle.
COOKING CONDITION
When the door is closed from the open position and Memory
pad is touched the, following will occur:
1. The contacts of relays are closed and components
connected to the relays are turned on (For details, refer
to Figure O-3)
2. Rated voltage is supplied to the primary winding of the
power transformer and is converted to about 3.4 volts
output on the filament winding, and approximately 2030
volts on the high voltage winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a voltage
doubler circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feedbox, and then into the cavity where the food is placed to
be cooked.
5. Upon completion of the cooking time, the oven will revert
to the IDLE condition.
6. When the door is opened during a cook cycle, monitor
switches (1) & (2), door sensing switch, secondary
interlock switches (1), (2) and primary interlock relays
(1), (2) are activated with the following results. The
circuits to the high voltage components are de-energized,
and the digital read-out displays " . " and cooking is
cancelled (in the case of Memory cooking).
7. The monitor switch (1) is electrically monitoring the
operation of the secondary interlock switch (1) and
primary interlock relay (1), and monitor switch (2) is
electrically monitoring the operation of the secondary
interlock switch (2) and primary interlock relay (2), and
monitor switches (1), (2) are mechanically associated
with the door so that it will function in the following
sequence.
(1) When the door opens from a closed position, the contacts
of the primary interlock relays (1), (2) and secondary
interlock switches (1), (2) open. Then the monitor switch
contacts close.
(2) When the door is closed from the open position, the
monitor switches (1), (2) contacts first open, and then the
contacts of the secondary interlock switches (1), (2)
close.
If the secondary interlock switches (1), (2) and primary interlock
relays (1), (2) fail with their contacts closed when the door is
opened, the closing of the monitor switches (1), (2) contacts will
form a short circuit through the monitor fuse, secondary interlock switches (1), (2) and primary interlock relays (1), (2),
causing the monitor fuse to blow.
VARIABLE POWER COOKING FOR R22GT-F
Note: R-22VG-F has only 100% power level.
When Variable Cooking Power is programmed, the rated
voltage A.C. is supplied to the power transformer intermittently
through the contacts of relay (RY-2, RY-3). Relays RY-2 and
RY-3 are operated by the control unit within an interval second
time base. Microwave power operation is as follows:
POWER LEVEL ON TIME OFF TIME
100% 32 sec. 0 sec.
90% 30 sec. 2 sec.
80 % 26 sec. 6 sec.
70% 24 sec. 8 sec.
60% 22 sec. 10 sec.
50% 18 sec. 14 sec.
40% 16 sec. 16 sec.
30% 12 sec. 20 sec.
20% 8 sec. 24 sec.
10% 6 sec. 26 sec.
0% 0 sec. 32 sec.
Note: The ON/OFF time ratio does not exactly correspond
with the percentage of microwave power, because
approx. 2 seconds are needed for heating of the
magnetron filament.
6
R-22GT-F
(
)
(
)
R-22GV-F
TWO MAGNETRON OPERATION SYSTEM
Two magnetrons (1), (2) are equipped in order to get higher
microwave power output. The primary windings of the
power transformers (1), (2) are connected so that each
magnetron can be oscillated alternatively according to the
frequency of the power supply. Refer to the Figure B-1.
COMMERCIAL
FREQUENCY
(60HZ)
POWER OUTPUT
BY MAGNETRON 1
POWER OUTPUT
BY MAGNETRON 2
Figure B-1. Operation of Magnetron
OPERATION OF
MAGNETRON
120V
60 Hz
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED OR 1 MINUTE AFTER COOK OFF
2. " . " APPEARS ON DISPLAY
BLK
WHT
GRN
FUSE
NOISE
FILTER
20A
RED
RED
RED
A7
A7
TAB2
RY-1
BLK
BLK
WHT
RED
RED
TAB1
A1
BLK
WHT
A3
YEL
BLK
OVEN TEMP. FUSE
WHT
WHT
PRIMARY
INTERLOCK
RELAY (1)
BRN
BRN
PRIMARY
INTERLOCK
RELAY (2)
RY-3 RY-2
B2 B1
DOOR
SENSING
SWITCHES
SECONDARY
INTERLOCK
SWITCHES
B3
H1
H3
MAGNETRON
THERMISTOR
BLU
BLU
MONITOR
SWITCHES
WHT
OVEN
THERMISTOR
FUSE (1)
POWER
TRANSFORMER(1)
MAG.NETRON TEMP.
BLK
MAG.NETRON
TEMP. FUSE (2)
POWER
TRANSFORMER(2)
WHT
BLK
CAPACITOR (1)
AC 2100V
H.V.
RECTIFIER (1)
CAPACITOR (2)
AC 2100V
1
MAGNETRON
2
MAGNETRON
WHT
WHT
Figure O-1. Oven Schematic-OFF Condition
7
H.V.
RECTIFIER (2)
R-22GT-F
(
)
(
)
(
)
(
)
R-22GV-F
SCHEMATIC
NOTE: CONDITION OF OVEN
1. FOR 1MINUTE AFTER DOOR OPENED.
2. " . " APPEARS ON DISPLAY.
RED
RED
120V
60 Hz
BLK
GRN
FUSE
NOISE
FILTER
20A
RED
A7
A7
TAB2
RY-1
RED
RED
A1
TAB1
A3
PRIMARY
INTERLOCK
RELAY (1)
BRN
BRN
PRIMARY
INTERLOCK
RELAY (2)
RY-3 RY-2
B2 B1
SECONDARY
INTERLOCK
SWITCHES
B3
H1
H3
BLU
BLU
MONITOR
SWITCHES
WHT
FUSE (1)
POWER
TRANSFORMER(1)
MAG.NETRON TEMP.
BLK
MAG.NETRON
TEMP. FUSE (2)
POWER
TRANSFORMER(2)
WHT
BLK
CAPACITOR (1)
AC 2100V
H.V.
RECTIFIER (1)
CAPACITOR (2)
1
MAGNETRON
WHT
Figure O-2. Oven Schematic-IDLE Condition (208 V Condition)
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. SELECTATIME PAD TOUCHED.
3. COOKING TIME PROGRAMMED.
4. START PAD TOUCHED.
NOISE
FILTER
BLK
120V
60 Hz
GRN
FUSE
20A
RED
RED
WHT
RED
A7
BLK
TAB2
A7
RY-1
BLK
WHT
RED
RED
A1
BLK
WHT
TAB1
YEL
BLK
OVEN TEMP. FUSE
WHT
WHT
A3
DOOR
SENSING
SWITCHES
PRIMARY
INTERLOCK
RELAY (1)
BRN
BRN
PRIMARY
INTERLOCK
RELAY (2)
RY-3 RY-2
B2 B1
MAGNETRON
THERMISTOR
WHT
SECONDARY
INTERLOCK
SWITCHES
B3
H1
H3
OVEN
THERMISTOR
BLU
BLU
MONITOR
SWITCHES
WHT
FUSE (1)
POWER
TRANSFORMER(1)
MAG.NETRON TEMP.
BLK
MAG.NETRON
TEMP. FUSE (2)
POWER
TRANSFORMER(2)
WHT
BLK
AC 2100V
H.V.
RECTIFIER (2)
CAPACITOR (1)
AC 2100V
H.V.
RECTIFIER (1)
CAPACITOR (2)
2
MAGNETRON
1
MAGNETRON
WHT
YEL
WHT
BLK
BLK
WHT
BLK
WHT
BLK
OVEN TEMP. FUSE
WHT
WHT
DOOR
SENSING
SWITCHES
MAGNETRON
WHT
THERMISTOR
OVEN
THERMISTOR
Figure O-3. Schematic-Cooking Condition (208 V Condition)
8
AC 2100V
H.V.
RECTIFIER (2)
2
MAGNETRON
DESCRIPTION AND FUNCTION OF COMPONENTS
R-22GT-F
R-22GV-F
DOOR OPEN MECHANISM
1. The door release lever is pulled.
2. The upper latch head is lifted up by the linked door
release lever.
3. The latch lever is lifted up by the door release lever.
4. The joint lever is lifted up by the latch lever.
5. The lower latch head is lifted up by the joint lever.
6. Now both latch heads are lifted up, so they can be
released from the latch hook.
7. Now the door can be opened.
Door release
lever
Joint lever
Latch lever
Latch head
Latch head
Switch lever A
Monitor switch (2)
Monitor switch (1)
Latch hook
Switch lever B
Secondary interlock
switch (2)
Secondary interlock
switch (1)
Door sensing switch
Switch lever C
Figure D-1. Door Open Mechanism
DOOR SENSING SWITCH
The door sensing switch is activated by the latch head of the
door and switch lever C. When the door is opened, the
contacts of the switch open and interrupt the circuit to the
coils of the primary interlock relays (1), (2). The contacts of
the primary relays (1), (2) then open and interrupt the circuit
to the primary winding of the power transformers. At this
time, the contacts of relay RY1 close and the blower motor,
stirrer motors and oven lamps are energized for 1 minute.
SECONDARY INTERLOCK SWITCHES (1), (2)
The secondary interlock switches (1), (2) are activated by
the upper latch head of the door and switch lever B. When
the door is opened, the contacts of the switch open and
interrupt the circuit to the primary winding of the power
transformers (1), (2).
MONITOR SWITCHES (1), (2)
The monitor switches (1), (2) are mounted in the upper
position of the latch hook. The monitor switches are activated by the upper latch head of the door and switch lever
A. When the door is opened, the contacts of the monitor
switches close. Monitor switch (1) is intended to render the
oven inoperative by means of blowing the monitor fuse,
when the contacts of the primary interlock relay (1) and
secondary interlock switch (1) fail to open when the door is
opened. Monitor switch (2) is intended to render the oven
inoperative by means of blowing the monitor fuse, when the
contacts of the primary interlock relay (2) and secondary
interlock switch (2) fail to open when the door is opened.
Functions:
With the door shut, the contacts of the door sensing switch
and the secondary interlock switches (1), (2) are closed and
the contacts of the monitor switches (1), (2) are open.
1. When the door is opened, the contact of the door sensing
switch and secondary interlock switches (1), (2) are
opened first, then the contact of the monitor switches (1),
(2) are closed.
2. As the door goes to a closed position, the contacts of the
monitor switches (1), (2) are opened first, then the
contacts of the door sensing switch and the secondary
interlock switches (1), (2) close.
3. If the door is opened, and the contacts of the primary
interlock relay and secondary interlock switch of the
same circuit fail to open, the monitor fuse blows
simultaneously with closing of the monitor switch contacts
of that circuit (1 or 2).
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAYS (1), (2), SECONDARY INTERLOCK SWITCHES (1), (2) AND
MONITOR SWITCHES (1), (2) FOR PROPER
OPERATION. (REFER TO CHAPTER "TEST
PROCEDURE").
NOTE: MONITOR FUSE AND SWITCH ARE REPLACED
AS AN ASSEMBLY.
MAGNETRON TEMPERATURE FUSES (1), (2)
The temperature fuses (1), (2) located on the top of the
upper and lower waveguide, are designed to prevent damage to the magnetrons (1), (2). If an over heated condition
develops in the tube due to blower motor failure, obstructed
air ducts, dirty or blocked air intake, etc., the circuit to the
magnetrons are interrupted. Under normal operation, the
temperature fuses remains closed. However, when abnormally high temperatures are generated within the magnetron,
the temperature fuse will open at 302˚F (150˚C) causing the
microwave energy to stop. The defective temperature fuse
must be replaced with new rated one.
OVEN TEMPERATURE FUSE
The temperature fuse, located on the side of the exhaust
duct assembly, 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 temperature fuse will
open. Under normal operation, the oven temperature fuse
remains closed. However, when abnormally high temperatures are generated within the oven cavity, the oven temperature fuse will open at 248˚F (120˚C), causing the oven
to shut down. The defective temperature fuse must be
replaced with new rated one.
9
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OVEN THERMISTOR
The thermistor is a negative temperature coefficient type.
The temperature in the exhaust duct is detected through the
resistance of the thermistor.
If the temperature is high, the control panel will display “EE7”
and the oven will stop to avoid overheating and catching fire.
If the thermistor is open, the control panel will display "EE6"
and the oven will stop.
MAGNETRON THERMISTOR
The thermistor is a negative temperature coefficient type.
The air temperature around the upper magnetron is detected through the resistance of the thermistor.
If the temperature is high, the control panel will display
"EE17" and the oven will stop to protect the lower magnetron
against overheat.
BLOWER MOTOR
The blower motor drives a blade which draws external cool
air into the oven. This cool air is directed through the air
vanes surrounding the magnetrons and cools the
magnetrons. This air is channelled through the oven cavity
to remove steam and vapours given off from the heating
foods. It is then exhausted through the exhausting air vents
at the oven cavity.
STIRRER MOTOR
The upper and lower stirrer motors drive stirrer antennas to
stir the microwave radiation from the upper and lower
waveguides.
OVEN LAMP
The oven cavity light illuminates the interior of the oven so
that food being cooked can be examined visually through
the door window without having to open the door. The oven
lamp is on during the cooking cycle and idle condition.
NOISE FILTER
The noise filter prevents the radio frequency interference
that might flow back in the power circuit.
TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many
of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which
will be found in the "Test Procedure "section.
IMPORTANT: If the oven becomes inoperative because of a blown monitor fuse, check the monitor switches (1), (2),
primary interlock relays RY2, RY3, door sensing switch and secondary interlock switches (1), (2), before
replacing the monitor fuse. If monitor fuse is replaced, the monitor switch (1) and/or (2) must also be replaced.
Use part FFS-BA033WRKZ 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 two high voltage capacitors.
4. Disconnect the leads to the primaries of the two power transformers.
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 two high voltage capacitors.
4. Reconnect the 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.
10
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CK = Check / RST = Reset / RE = Replace
TEST PROCEDURE
POSSIBLE CAUSE AND
DEFECTIVE PARTS
C
O
N
D
I
T
I
O
N
Home fuse blows when power
C
cord is plugged into wall
O
receptacle.
N
O
D
Monitor fuse blows when power
F
I
cord is plugged into wall
F
T
receptacle.
I
O
" . " does not appear in display
N
when power cord is first plugged
PROBLEM
into wall receptacle.
Blower motor does not operate.
(Oven lamp and stirrer motors
go on for 1 minute after door is
opened.)
C
Blower motor, oven lamp and
O
stirrer motors do not go on for 1
N
I
minute after door is opened.
D
D
I
Blower motor and stirrer motors
L
T
E
go on but oven lamp do not light
I
for 1 minute after door is
O
N
opened.
Blower motor, oven lamp and
stirrer motors keep going on
after more than 1 minute when
door is opened and closed.
Blower motor, oven lamp and
stirrer motors do not go on in
cook cycle.
Oven goes into a cook cycle but
shuts down before and off
cooking cycle.
C
C
Oven does not go into cook
O
O
N
cycle when START pad is
O
D
touched.
K
I
I
Low or no power is produced
T
N
I
during cooking condition. (The
G
O
food is heated incompletely or
N
not heated at all.)
Extremely uneven heating is
produced in oven load (food).
Variable cooking does not
operates properly, except HIGH
power functions.
"EE1" Magnetron (1) failure.
"EE2" Magnetron (2) failure.
"EE3" Magnetron (1) and (2)
failure.
"EE6" Oven thermistor failure.
E
M
"EE7" Exhaust air temperature
R
O
R
is too high.
D
O
E
"EE8" Relay melt short.
R
"EE9" Maximum time is
exceeded.
"EE16" Magnetron thermistor is
open.
"EE17" Magnetron temperature
is too high.
ABCDEF FGH I ICKCK J KLMNNNOCKCKCKCKCK
MAGNETRON (1), (2)
POWER TRANSFORMER (1), (2)
H.V. RECTIFIER (1), (2)
HIGH VOLTAGE CAPACITOR (1), (2)
SECONDARY INTERLOCK SWITCH (1), (2)
PRIMARY INTERLOCK SYSTEM (1), (2)
DOOR SENSING SWITCH
MONITOR SWITCH (1), (2)
MONITOR FUSE
MAGNETRON TEMP. FUSE (1), (2)
OVEN TEMPERATURE FUSE
OVEN LAMP OR SOCKET
BLOWER MOTOR
OVEN THERMISTOR
MAGNETRON THERMISTOR
NOISE FILTER
TOUCH CONTROL PANEL
KEY UNIT
RELAY (RY-1)
RELAY (RY-2)
RELAY (RY-3)
OPEN FOIL PATERN ON P.W.B.
STIRRER MOTORS
AIR FLOW BLOCKED
LOOSE WIRING
SHORT IN POWER SUPPLY CORD
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(2)
(1)
(2)
(1)
(2)
RST RST
CKJ
NO POWER AT OUTLET
LOW POWER SUPPLY VOLTAGE
EXCEED MAX. HEATING TIME
NO LOAD OPERATION
11
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TEST PROCEDURES
PROCEDURE
LETTER
A MAGNETRON ASSEMBLY TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
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. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads
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
should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following
components or wiring: silicon rectifier, high voltage capacitor and power transformer. This test will require
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:
COMPONENT TEST
1. Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water with
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 100% POWER selecting more than 60 seconds
cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second hand 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. Subtract the cold water temperature from the hot water temperature. The normal result should be 36.5
to 67.9˚F(20.3 to 37.7˚C) rise in temperature. If the water temperatures are accurately measured and
tested for the required time period the test results will indicate if the magnetron tube has low power
output (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
temperature rise test indicates a power output well beyond the normal limits. The test is only accurate
if the power supply line voltage is 208/230 volts and the oven cavity is clean.
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 two high voltage capacitors.
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 106 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.
12
TEST PROCEDURES
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PROCEDURE
LETTER
8. Run the oven and check all functions.
(HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.)
C HIGH VOLTAGE RECTIFIER (1) AND/ OR (2) TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
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: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
D HIGH VOLTAGE CAPACITOR (1) AND/ OR (2) TEST
COMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
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.
E SECONDARY INTERLOCK SWITCH (1) AND/ OR (2) TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (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.
F 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 two high voltage capacitors.
4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal
13
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