SHARP R-1405, R1406 Service Manual

SERVICE MANUAL
S92M198R1405E
OVER THE RANGE
MICROWAVE OVEN
R-1405 R-1406
MODELS
R-1405 R-1406
R-1405
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 the 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
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 .........................................................................................................................................................7
TROUBLESHOOTING GUIDE .............................................................................................................................11
TEST PROCEDURE ............................................................................................................................................13
TOUCH CONTROL PANEL ASSEMBLY .............................................................................................................22
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................................26
PICTORIAL DIAGRAM ........................................................................................................................................34
POWER UNIT CIRCUIT.......................................................................................................................................35
LSI UNIT CIRCUIT...............................................................................................................................................36
PRINTED WIRING BOARD .................................................................................................................................37
PARTS LIST........................................................................................................................................................38
PACKING AND ACCESSORIES .........................................................................................................................40
SHARP CORPORATION
This document has been published to be used for after sales service only. The contents are subject to change without notice.
1
R-1405 R-1406
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPO­SURE TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open. (b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other
microwave source, and make repairs as necessary: (1) interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation
and transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be
performed on each oven prior to release to the owner.
BEFORE SERVICING
Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement Procedure outlined in this service manual. If microwave emissions level is in excess of the specified limit, contact SHARP ELECTRONICS CORPORATION immediately @1-800-237-4277.
If the unit operates with the door open, service person should 1) tell the user not to operate the oven and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's Center for Devices and Radiological Health immediately.
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.
2
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-1405 R-1406
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 re- examine 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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R-1405 R-1406
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 switch shall prevent microwave radiation emission in excess of the requirement as above mentioned, secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface of the oven.
B. Preparation for testing: Before beginning the actual measurement of leakage, proceed as follows:
1) Make sure that the actual instrument is operating normally as specified in its instruction booklet. Important:
Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.
2) Place the oven tray in the oven cavity.
3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5½C (68½F) 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 switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
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SERVICE MANUAL
OVER THE RANGE
MICROWAVE OVEN
PRODUCT DESCRIPTION
R-1405 R-1406
R-1405/ R-1406
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-1405 and R-
1406. 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.
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 “Д 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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R-1405 R-1406
PRODUCT SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts / 13.5 Amperes
60 Hertz Single phase, 3 wire grounded
Power Output 950 watts (IEC TEST PROCEDURE)
Operating frequency of 2450MHz
Case Dimensions Width 29-15/16"
Height 15- 9/16" Depth 16-1/4"
Cooking Cavity Dimensions Width 17-1/2"
Height 14-15/16"
1.5 Cubic Feet Depth 9-7/8" Hood lamp 2 bulbs, 20W 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
KEEP WARM pad, POPCORN pad, HOT WATER pad REHEAT CENTER pads, COOK CENTER pads DEFROST CENTER pads, Number selection pads POWER LEVEL pad, TIMER / CLOCK pad LIGHT button, FAN button, STOP/CLEAR button, START/ MINUTE PLUS button,
Oven Cavity Light 20W 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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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 dedicated line, 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
R-1405 R-1406
OVEN DIAGRAM
1
2
6
1. Oven door with see-through window.
2. Door hinges.
3. Waveguide 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. One touch door open button.
8. Auto Touch control panel
9. Time display: Digital display, 99 minutes 99 seconds.
10
9
5
8
4
13
3
14
7
15
10
10
12
11
10.Ventilation openings.
11.Light Cover.
12.Grease filters.
13.Removable turntable. The turntable will rotate clockwise or counterclockwise. Only remove for cleaning.
14.Removable turntable support.
15. Power supply cord
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R-1405 R-1406
CONTROL PANEL
NOTE: Some one-touch cooking features such as "MINUTE PLUS" are disabled after three minutes when the oven is not
used. These features are automatically enabled when the door is opened and closed or STOP/CLEAR button is pressed.
6
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
R-1405 R-1406
The following is a description of component functions during oven operation.
OFF CONDITION
Closing the door activates the door sensing switch and primary interlock switch. (In this condition, the monitor switch contacts are opened.) When oven is plugged in, 120 volts A.C. is supplied to the control unit. (Figure O-1).
1. The display will show flashing "88 : 88". To set any program or set the clock, you must first touch the STOP/CLEAR button. The display will clear, and " : " will appear .
COOKING CONDITION
Program desired cooking time touching the NUMBER pads. When the START button is touched, the following operations occur:
1. The contacts of relays are closed and components connected to the relays are turned on as follows. (For details, refer to Figure O-2)
RELAY CONNECTED COMPONENTS RY 1 Oven lamp / Fan motor / Turntable motor RY2 Power transformer RY3, RY4 Hood fan motor RY5, RY6 Hood lamp
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, primary interlock switch, relay (RY1) and secondary interlock relay (RY2) are activated with the following results. The circuits to the cooling fan motor, the turntable 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. The monitor switch is electrically monitoring the operation of the primary interlock switch and secondary 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
secondary interlock relay (RY2) and primary interlock switch open their contacts. And contacts of the relay (RY1) remains closed. 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 primary interlock switch and door sensing switch close. And contacts of the relay (RY1)
open. If the primary interlock switch and secondary 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, primary interlock switch, relay (RY1) and secondary interlock relay (RY2), causing the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120 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. 3 seconds are needed for heating of the magnetron filament.
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R-1405 R-1406
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.
To Duct
Hood Fan Motor
Hood Intake Duct R
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.
Hood Fan Motor
Hood Intake Duct R
To Duct
To 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-240 must be provided to filter the air before it leaves the oven.
Hood Fan Motor
Hood Exhaust Louver
Hood Intake Duct R
Charcoal Filter
8
FUSE 20A
120VAC 60Hz
ORG
RED
BLK
BLK
GRN
GND
WHT
BLU
NOTE: " " indicates components with potential above 250V.
CAVITY THERMAL CUTOUT
PPL
PPL
ORG
HOOD FAN THERMAL CUT OUT
BLU
YLW
BLK
RED
HOOD MOTOR
A5
B3
BLK
WHT
HOOD CAPACITOR
RED
RED
A1
RY4
A3
BRN
HL
YLW
WHT
MAGNETRON TEMPERATURE FUSE
CONTROL UNIT
RY5
B1
N.O.
BRN
HL
WHT
HOOD LAMP
WHT
OVEN LAMP RELAY
(RY1)
COM.
GRY
GRY
WHT
GRY
RED BLK
N.O.
ORG
BRN
ORG
OVEN LAMP
GRY
PRIMARY INTERLOCK SWITCH
BLK
ORG
(RY2)
SECONDARY INTERLOCK RELAY
TTM
WHT WHT
BRN
TURN TABLE MOTOR
WHT
COM.
RED ORG
RED
E2
E1
AH SENSOR
F1
F2
F3
RED
FMOL
WHT
DOOR SENSING SWITCH
FAN MOTOR
MONITOR SWITCH
WHT
WHT
WHT
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
POWER TRANSFORMER
RED
RED
WHT
HIGH VOLTAGE CAPACITOR xx uF
MAGNETRON
R-1405 R-1406
FUSE 20A
120VAC 60Hz
BLK
ORG
RED
BLK
GRN
GND
WHT
BLU
CAVITY THERMAL CUTOUT
PPL
PPL
ORG
HOOD FAN THERMAL CUT OUT
BLU
YLW
BLK
RED
BLK
HOOD MOTOR
WHT
A5
B3
RED
RY4
HOOD CAPACITOR
A1
RED
YLW
Figure O-1. Oven Schematic-Off Condition
MAGNETRON TEMPERATURE FUSE
CONTROL UNIT
RY5
B1
A3
BRN
BRN
HL
HOOD LAMP
WHT
HL
WHT
OVEN LAMP RELAY
N.O.
GRY
GRY
WHT
WHT
(RY1)
COM.
GRY
RED BLK
N.O.
ORG
BRN
ORG
OVEN LAMP
GRY
PRIMARY INTERLOCK SWITCH
BLK
ORG
(RY2)
SECONDARY INTERLOCK RELAY
TTM
WHT WHT
COM.
BRN
TURN TABLE MOTOR
WHT
RED
ORG
RED
E2
DOOR SENSING SWITCH
E1
AH SENSOR
F1
F2
F3
RED
FMOL
WHT
FAN MOTOR
MONITOR SWITCH
WHT
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. COOKING TIME PROGRAMMED.
3. VARIABLE COOKING CONTROL "HIGH".
4. "START" BUTTON PRESSED.
POWER TRANSFORMER
RED
MAGNETRON
RED
HIGH VOLTAGE
WHT
CAPACITOR xx uF
WHT
WHT
Figure O-2. Oven Schematic-Cooking Condition
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R-1405 R-1406
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the control panel, refer to the Figure D-1. When the open button is pushed, the open button pushes up the open lever, and then the open lever pushes up the latch head. The latch heads are moved upward and released from latch hook. Now the door will open.
Latch heads
Latch hook
Door sensing
Door
Open lever
switch
Monitor switch
Primary interlock switch
Figure D-1. Door Open Mechanism
DOOR SENSING AND PRIMARY INTERLOCK SWITCHES
The primary interlock switch is mounted in the lower posi­tion of the latch hook and the door sensing switch in the secondary 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 secondary interlock system con­sists of the door sensing switch and secondary 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 secondary interlock relay (RY2) and primary interlock switch fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact close (to the ON condition) due to their being normally closed. At this time the secondary interlock relay (RY2) and primary interlock switch are in the OFF condition (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 primary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)
3. If the door is opened, and the secondary interlock relay (RY2) and primary interlock 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, SECONDARY INTERLOCK RELAY (RY2), RELAY (RY1), PRIMARY 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 on the fan duct assembly 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 302½F (150½C) causing the oven to shut down.
NOTE: This is a fuse. It does not reset.
THERMAL CUT-OUT (HOOD )
This thermal cut-out located on the right base plate flange (turntable motor side). 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 140½F (60½C) or higher, thus removing this hot air from around microwave oven. When the temperature around the thermal cut-out drops to 113½F (45½C) or lower, the thermal cut-out shuts off the hood fan motor.
THERMAL CUT-OUT (CAVITY )
This thermal cut-out is located on the bottom 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 293½F (145½C) causing the oven to shut down. The defective thermal cut-out must be replaced with a new one.
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
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R-1405 R-1406
vapors given off from the heating foods. It is then exhausted
supplied duct system, or discharged back into the kitchen.
through the exhausting air vents at the oven cavity.
HOOD LAMP
HOOD FAN MOTOR
The hood fan motor is a one-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. This air is then expelled either vertically or horizontally through the customer
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 LIGHT button.
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)
secondary interlock relay (RY2), door sensing switch and primary 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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TEST PROCEDURE
D HIGH VOLTAGE CAPACITOR
C H.V. RECTIFIER
B POWER TRANSFORMER
A MAGNETRON
POSSIBLE CASE AND
DEFECTIVE PARTS
E
F PRIMARY INTERLOCK SWITCH
G
SECONDARY INTERLOCK SYSTEM
TEMPERATURE FUSE OR THERMAL CUT-OUT
J HOOD HERMAL CUT-OUT
I MONITOR FUSE
H MONITOR SWITCH
M KEY UNIT
L CONTROL UNIT
K HOOD FAN MOTOR
N RELAY (RY-2)
N RELAY (RY-1)
N RELAY (RY-3)
O DEFROST CENTER
N RELAYS (RY-5), (TY6)
N RELAY (RY-4)
P FOIL PATERN ON P.W.B.
RE SHORT IN POWER CORD
CK OPENED OR SHORTED WIRING
CK HOOD MOTOR CAPACITOR
RE HOOD LAMP OR SOCKET
RE TURNTABLE MOTOR
RE FAN MOTOR
RE OVEN LAMP OR SOCKET
R-1405
R-1406
CK LOW VOLTAGE
CK NO POWER AT OUTLET
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CONDITION
OFF
CONDITION
IDLE
CONDITION
MICROWAVE
COOKING CONDITION
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. Display does not operate properly when STOP/CLEAR button is touched.
(The time of day should appear on the display with beep sound during normal condition.)
Oven lamp does not light with door is opened. Hood fan motor operates when power cord is first plugged into wall
receptacle. Temperature of oven base seems more than 140ûF (60ûC) 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 LIGHT button is pressed.
Hood fan motor does not rotate at all with touched FAN button.
Oven lamp does not light in cook cycle. (But it does light when door is opened.)
Fan motor does not operate. (Oven lamp and turntable motor operate.) Turntable motor does not operate (Oven lamp lights and fan motor
operate.) Oven does not go into cook cycle when START button 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). Variable cooking does not operate properly except Cooking Power 10 (P-
HI) mode. Function of DEFROST CENTER does not operate properly. Oven goes into DEFROST CENTER but food is not defrosted well.
CK = Check / RE = Replace
TEST PROCEDURES
R-1405 R-1406
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 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. 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:
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 POWER 10(HIGH) 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 29.2 to 54.2½F(16.2 to 30.1½C) 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 120 volts and the oven cavity is clean.
COMPONENT TEST
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 83 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.
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