Sharp R-1480, R-1482, R-1481 User Manual
SER VICE MANU AL
S3807R1480X//
OVER THE RANGE
MICROWAVE OVEN
R-1480
R-1481
R-1482
MODELS
R-1480
R-1481
1 Coffee/tea
CUSTOM HELP
2 Roll/muffin, fresh
BREAKFAST
3 Roll/muffin, frozen
4 Hot cereal
5 Scrambled eggs
1 Dinner plate
SNACKS &
POPCORN
2 Pasta/casserole
3 Frozen entree
REHEAT
4 Frozen snack
5 Pizza, slice
1 Baked potatoes
COMPU DEFROST
2 Fresh vegetables
COMPU COOK
3 Frozen vegetables
4 Rice
5 Ground meat
12345
67890
POWER
KITCHEN TIMER
LEVEL
MINUTE
CLOCK
PLUS
TURNTABLE
STOP
ON/OFF
START
CLEAR
TOUCH ON
WORK
NIGHT
LIGHT
FAN
LIGHT
HI/LO
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..)
TABLE OF CONTENTS
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 ............................................................................................................................11
TEST PROCEDURE............................................................................................................................................12
TOUCH CONTROL PANEL ASSEMBLY ............................................................................................................21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................26
PICTORIAL DIAGRAM ........................................................................................................................................34
CONTROL PANEL CIRCUIT ...............................................................................................................................35
PRINTED WIRING BOARD .................................................................................................................................36
PARTS LIST ........................................................................................................................................................37
PACKING AND ACCESSORIES .........................................................................................................................42
R-1482
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-1480
R-1481
R-1482
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 releasing 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 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
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
Don't Touch !
Danger High Voltage
R-1480
R-1481
R-1482
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
seconds after the oven has been switched off. Wait for 60
seconds and then short-circuit the connection of the highvoltage capacitor (that is the connecting lead of the highvoltage rectifier) 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 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, 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.
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.
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MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
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 secondary interlock switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
2
SERVICE MANUAL
R-1480
R-1481
R-1482
OVER THE RANGE
MICROWAVE OVEN
R-1480 / R-1481 / R-1482
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP OVER THE RANGE MICROWAVE OVEN, R-1480, R-1481,
R-1482.
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 not any other visible damage with the oven.
PRODUCT DESCRIPTION
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
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.
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
PARTS LIST
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PRODUCT SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts / 14.3 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output 950 watts (IEC-705 TEST PROCEDURE)
Operating frequency of 2450MHz
Convection Power Output 1700 watts
Case Dimensions Width 29-15/16"
Height 16-3/8"
Depth 15- 1/4" (Not including the door handle)
Cooking Cavity Dimensions Width 20-1/4"
Height 8-3/16"
1.4 Cubic Feet Depth 14-1/2"
Hood lamp 2 bulbs, 30W x 2, Incandescent light bulbs
Hood fan Approx. 300 C.F.M.
Control Complement Touch Control System
Clock ( 1:00 - 12:59 )
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
CUSTOM HELP pad, BREAKFAST pad, POPCORN pad,
SNACKS & REHEAT pad, COMPU DEFROST pad, COMPU COOK pad,
Number selection pads, POWER LEVEL pad, KITCHEN TIMER / CLOCK pad
MINUTE PLUS pad, TURNTABLE ON / OFF pad, START / TOUCH ON pad
WORK LIGHT pad, NIGHT LIGHT pad, FAN HI / LO pad
Oven Cavity Light 30W x 1 Incandescent light bulb
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
Weight Approx. 55 lbs.
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.
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R-1481
R-1482
Electrical Requirements
The oven is equipped with a 3-prong grounding plug. DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE
GROUNDING PIN FROM THE PLUG.
The power supply cord and plug must be connected to a separate 120 Volt AC, 60 Hz, 15 Amp. or more branch circuit, using
a grounded receptacle. The receptacle should be located inside the cabinet directly above the Microwave Oven/Hood
system mounting location.
3-Pronged Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
OVEN DIAGRAM
9
9
1
3
5
2
4
6
12
13
1. Oven door with see-through window.
2. Door hinges.
3. Stirrer cover.
4. Turntable motor shaft.
5. Oven lamp.
It will light when oven is operating or door is open.
6. Door latches.
The oven will not operate unless the door is securely closed.
7. Auto-Touch control panel.
8
7
14
10
11
8. Time display: Digital display, 99 minutes 99 seconds.
9. Ventilation openings.
10.Light Cover.
11.Grease filters.
12.Removable turntable.
The turntable will rotate clockwise or counterclockwise.
Only remove for cleaning.
13.Removable turntable support.
14. Power supply cord
5
R-1480
R-1481
R-1482
CONTROL PANEL
MIX CONV COOK LBS KG
CUSTOM HELP
POPCORN
COMPU DEFROST
TURNTABLE
BREAKFAST
SNACKS &
REHEAT
COMPU COOK
OFF HELP
1 Coffee/tea
2 Roll/muffin, fresh
3 Roll/muffin, frozen
4 Hot cereal
5 Scrambled eggs
1 Dinner plate
2 Pasta/casserole
3 Frozen entree
4 Frozen snack
5 Pizza, slice
1 Baked potatoes
2 Fresh vegetables
3 Frozen vegetables
4 Rice
5 Ground meat
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67890
POWER
LEVEL
KITCHEN TIMER
CLOCK
MINUTE
PLUS
TURNTABLE
ON/OFF
WORK
LIGHT
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 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 , , ,
,, , ,
and .
STOP
CLEAR
NIGHT
LIGHT
START
TOUCH ON
FAN
HI/LO
To set any program or set the clock, you must first touch
the STOP/CLEAR pad. The display will clear, and " : "
will appear .
COOKING CONDITION
Program desired cooking time touching 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)
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RELAY CONNECTED COMPONENTS
RY1 Oven lamp / Fan motor / Stirrer motor
RY2 Power transformer
RY3 Turntable motor
RY4 Hood fan motor
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.3 volts
A.C. output on the filament winding, and approximately
2000 volts A.C. 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 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, door sensing switch, secondary interlock switch
and primary interlock relay are activated with the following
results. The circuits to the stirrer motor, the cooling fan
motor, the turntable motor, and the high voltage
components are de-energized, and the digital read-out
displays the time still remaining in the cook cycle when
the door was opened.
7. The monitor switch is electrically monitoring the operation
of the secondary interlock switch and primary interlock
relay (RY2) and is mechanically associated with the door
so that it will function in the following sequence.
(1) When the door opens from a closed position, the
primary interlock relay and secondary interlock switch
open their contacts, and then the monitor switch
contacts close.
(2) When the door is closed from the open position, the
monitor switch contacts first open, and then the
contacts of the secondary interlock switch and door
sensing switch close.
If the secondary interlock switch and primary interlock relay
(RY2) fail with their contacts closed when the door is
opened, the closing of the monitor switch contacts will form
a short circuit through the monitor fuse, secondary interlock
switch and primary interlock relay (RY2), causing the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
volts A.C. is supplied to the power transformer intermittently
through the contacts of relay (RY2) which is operated by the
control unit within an interval second time base. Microwave
power 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.
COMPU COOK
COMPU COOK will automatically compute the microwave
power and cooking time. Set the desired program by touching one of the COMPU COOK pad, and number pad to
select menu. Enter the weight or quantity by touching the
Number pads. When the START pad is touched, the following operations occur:
1. The COOK indicator will light.
2. The cooking time will appear on the display and start
counting down to zero. The cooking time is adjusted
automatically according to the weight of the food.
3. The shut-off relays (RY1, RY2 and RY3) are energized,
turning on the oven lamp, turntable motor, cooling fan
motor and convection motor. The power supply voltage
is applied to the heating element.
4. Now, the oven is in the microwave cooking mode.
COMPU DEFROST COOKING
The COMPU DEFROST key is a special function key to
defrost meats and poultry faster and better. COMPU DEFROST automatically defrosts roast beef, etc.. Touch the
COMPU COOK pad and number pad to select menu and
enter the food weight by touching the number pads. When
the START pad is touched, the oven will cook according to
the special cooking sequence.
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VENTILATION METHODS HOT AIR EXHAUST
1. VERTICAL VENTING
For this venting method, hot air rising from the
conventional range below is drawn in by the hood fan
motor through the grease filters at the right and left sides
of the base cover, up through the right and left sides of
the oven cavity, then discharged vertically at rear center
top of the oven, into the customer's vent system.
_: AIR FLOW
TO DUCT
HOOD FAN MOTOR
HOOD
INTAKE
DUCT
GREASE
FILTER
2. HORIZONTAL VENTING
The air handing is the same as VERTICAL VENTING
except that the final air discharge is directed horizontally
out from the top rear of the oven into the customer's vent
system.
TO DUCT
_: AIR FLOW
HOOD FAN MOTOR
HOOD
INTAKE
DUCT
GREASE
FILTER
3. RE-CIRCULATION (INSIDE VENTING)
The air handing is the same as VERTICAL VENTING
except that the final air discharge is directed horizontally
through the upper front of the oven into the kitchen. IN
this case, the accessory charcoal filter RK-230 must be
provided to filter the air before it leaves the oven.
_: AIR FLOW
HOOD FAN MOTOR
HOOD EXHAUST
LOUVER
HOOD
INTAKE
DUCT
CHARCOAL
FILTER
TO DUCT
8
CAVITY
THERMAL CUT-OUT
MAGNETRON
TEMPERATURE FUSE
R-1480
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R-1482
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. CLOCK APPEARS ON DISPLAY
FUSE
20A
120 V AC.
60 Hz
BLKWHT
GRN
GND
HOOD FAN
THERMAL
CUT OUT
B7
B5
B3
B1
HOOD
MOTOR
CAVITY
THERMAL CUT-OUT
CONTROL UNIT
RY4
RY5
High
N.C.
Low
HOOD
CAPACITOR
A1 A3 B9 A7 A5 N.O.
HOOD
LAMP
SSR
RY3 RY1
TTM
HL HL
TURNTABLE
MOTOR
FAN
MOTOR
SECONDARY
INTERLOCK
SWITCH
Figure O-1. Oven Schematic-Off Condition
MAGNETRON
TEMPERATURE FUSE
COM. N.O.
OVEN LAMP
FM
COM.
OL
PRIMARY
INTERLOCK
RELAY
RY2
STM
STIRRER
MOTOR
E1
E2
DOOR
SENSING
SWITCH
POWER
TRANSFORMER
MAGNETRON
MONITOR
SWITCH
HIGH VOLTAGE
CAPACITOR
0.94µF
HIGH VOLTAGE
RECTIFIER
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. COOKING TIME PROGRAMMED
3. VARIABLE COOKING CONTROL "HIGH"
4. "START" PAD TOUCHED
FUSE
20A
120 V AC.
60 Hz
BLKWHT
GRN
GND
HOOD FAN
THERMAL
CUT OUT
CONTROL UNIT
B7
B5
B3
B1
HOOD
MOTOR
RY4
RY5
High
N.C.
Low
HOOD
CAPACITOR
A1 A3 B9 A7 A5 N.O.
HOOD
LAMP
SSR
HL HL
Figure O-2. Oven Schematic-Cooking Condition
RY3 RY1
TTM
TURNTABLE
MOTOR
FAN
MOTOR
SECONDARY
INTERLOCK
SWITCH
COM. N.O.
OVEN LAMP
FM
COM.
OL
PRIMARY
INTERLOCK
RELAY
RY2
STM
STIRRER
MOTOR
E1
E2
DOOR
SENSING
SWITCH
MONITOR
SWITCH
POWER
TRANSFORMER
HIGH VOLTAGE
CAPACITOR
0.94µF
HIGH VOLTAGE
RECTIFIER
MAGNETRON
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DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pulling the door handle, refer to the
Figure D-1.
Latch
Hook
Latch
Heads
Door
Door
Sensing
Switch
Monitor
Fuse
Monitor
Switch
Secondary
Interlock
Switch
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the lower
position of the latch hook and the door sensing switch in the
primary interlock system is mounted in the upper position of
the latch hook. They are activated by the latch heads on the
door. When the door is opened, the switches interrupt the
circuit to all components. A cook cycle cannot take place
until the door is firmly closed thereby activating both interlock switches. The primary interlock system consists of the
door sensing switch and primary interlock relay located on
the control circuit board.
MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the
latch head on the door while the door is closed. The switch
is intended to render the oven inoperative by means of
blowing the monitor fuse when the contacts of the primary
interlock relay (RY2) and secondary interlock switch fail to
open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the primary interlock relay (RY2) and
secondary interlock switch are in the OFF condition
(contacts open) due to their being normally open contact
switches. And the contacts of relay (RY1) are in the ON
condition (contacts close).
2. As the door goes to a closed position, the monitor switch
contacts are first opened and then the door sensing
switch and the secondary interlock switch contacts close.
(On opening the door, each of these switches operate
inversely.)
3. If the door is opened, and the primary interlock relay
(RY2) and secondary interlock switch contacts fail to
open, the monitor fuse blows simultaneously with closing
of the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK RELAY (RY2), SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION.
(REFER TO CHAPTER "TEST PROCEDURE").
NOTE: MONITOR FUSE AND SWITCH ARE REPLACED
AS AN ASSEMBLY
TEMPERATURE FUSE (MG)
The temperature fuse located near the waveguide is
designed to prevent damage to the magnetron if an over
heated condition develops in the tube due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the temperature fuse remains
closed. However, the temperature fuse will open at 302˚F
(150˚C) causing the oven to shut down.
THERMAL CUT-OUT (HOOD )
This thermal cut-out located on the right base plate. It is
designed to automatically turn on the hood fan motor
whenever the hot air rising from the conventional range
below causes the temperature at the thermal cut-out to rise
to 140˚F (60˚C) or higher, thus removing this hot air from
around microwave oven. When the temperature around the
thermal cut-out drops to 113˚F (45˚C) or lower, the thermal
cut-out shuts off the hood fan motor.
THERMAL CUT-OUT (CAVITY )
This thermal cut-out is located on the top of the oven cavity.
It is designed to prevent damage to the oven unit if the food
in the oven catches fire due to overheating produced by
improper setting of cooking time or failure of control unit.
Under normal operation, the thermal cut-out remains closed.
However, the thermal cut-out will open at 293˚F (145˚C)
causing the oven to shut down.
TURNTABLE MOTOR
The turntable motor rotates the turntable located on the
bottom of the oven cavity, so that the foods on the turntable
cook evenly during cooking. Turntable will turn in either
direction. The turntable motor can be turned off by touching
TURNTABLE ON/OFF pad.
COOLING FAN MOTOR
The cooling fan motor drives a blade which draws external
cool air. This cool air is directed through the air vanes
surrounding the magnetron and cools the magnetron. This air
is channelled through the oven cavity to remove steam and
vapors given off from the heating foods. It is then exhausted
through the exhausting air vents at the oven cavity.
HOOD FAN MOTOR
The hood fan motor is a two-speed, single-phase, double
pole induction type, requiring a hood fan capacitor. It is
located outside the upper rear part of the oven cavity, is to
remove, from around the oven, hot air rising from the
conventional electric or gas range over which it is installed.
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This air is then expelled either vertically or horizontally
through the customer supplied duct system, or discharged
back into the kitchen.
HOOD LAMP
The hood lamps are mounted at the hood lamp angle on the
base cover. The hood lamps can be turned off and on by
touching the WORK LIGHT pad or the NIGHT LIGHT pad.
STIRRER MOTOR
The stirrer motor drives the stirrer fan to stir the microwave
And also the brightness can be varied to high or low by
touching the WORK LIGHT pad or the NIGHT LIGHT pad.
radiation from the waveguide.
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 switch, relay (RY1)
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-BA016/
KiT 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. 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. Reconnect the power supply cord after the outer case is installed.
7. Run the oven and check all functions.
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CK LOW VOLTAGE
CK NO POWER AT OUTLET
RE SHORTED IN POWER CORD
CK OPENED OR SHORTED WIRING
CK HOOD MOTOR CAPACITOR
RE HOOD LAMP OR SOCKET
CK TURNTABLE OFF CONDITION
RE STIRRER MOTOR
RE TURNTABLE MOTOR
RE FAN MOTOR
RE OVEN LAMP OR SOCKET
P FOIL PATERN ON P.W.B.
O COMPU DEFROST
N RELAY (RY-5)
N RELAY (RY-4)
N RELAY (RY-3)
N RELAY (RY-2)
N RELAY (RY-1)
M KEY UNIT
L CONTROL UNIT
K HOOD FAN MOTOR
J HOOD HERMAL CUT-OUT
I MONITOR FUSE
H MONITOR SWITCH
G
PRIMARY INTERLOCK SYSTEM
F SECONDARY INTERLOCK SWITCH
E
TEMPERATURE FUSE OR THERMAL CUT-OUT
D HIGH VOLTAGE CAPACITOR
C H.V. RECTIFIER
B POWER TRANSFORMER
A MAGNETRON
CK = Check / RE = Replace
POSSIBLE CASE AND
DEFECTIVE PARTS
TEST PROCEDURE
PROBLEM
Home fuse blows when power cord is plugged into wall receptacle.
Monitor fuse blows when power cord is plugged into wall receptacle.
Display does not illuminate when power cord is first plugged into wall
receptacle.
CONDITION
Display does not operate properly when STOP/CLEAR key is touched.
(The time of day should appear on the display with beep sound during
normal condition.)
Hood fan motor operates when power cord is first plugged into wall
receptacle.
Oven lamp does not light with door is opened.
OFF
CONDITION
Temperature of oven base seems more than 140˚F (60˚C) because of
operation of the range below. But hood fan motor does not turn on
automatically. (Normally, food fan motor should be operating at low
speed.)
Hood lights do not turn on when WORK LIGHT pad or NIGHT LIGHT pad
is pressed.
Hood fan motor does not rotate at all with touched FAN HI/LO pad.
Speed of the hood fan motor does not change when the FAN HI/LO pad is
touched for this function.
Oven lamp does not light in cook cycle. (But it does light when door is
opened.)
IDLE
CONDITION
Fan motor does not operate. (Oven lamp and turntable motor 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.)
Turntable motor does not operate (Oven lamp lights and fan motor
operate.)
Oven goes into a cook cycle but extremely uneven heating is produced in
COOKING
CONDITION
MICROWAVE
oven load (food).
Variable cooking does not operate properly except Cooking Power 10 (P-
HI) mode.
Stirrer motor does not operate. (Other parts operate.)
Oven goes into COMPU DEFROST but food is not defrosted well.
Function of COMPU DEFROST does not operate properly.
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