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• DO NOT operate on a 2-wire extension cord during

repair and use.

• NEVER TOUCH any oven components or wiring during

operation.

• BEFORE TOUCHING any parts of the oven, always

remove the power plug from the outlet.

• For about 30 seconds after the oven stops, an electric

charge remains in the high voltage capacitor. When
replacing or checking, you must discharge the high
voltage capacitor by shorting across the two terminals
with an insulated screwdriver.

• 

Remove your watches whenever working close to or

replacing the Magnetron.

• DO NOT touch any parts of the control panel circuit. A

resulting static electric discharge may damage this
P.C.B.

• NEVER operate the oven with no load.
• NEVER injure the door seal and front plate of the oven

cavity.

• NEVER put iron tools on the magnetron.
• NEVER put anything into the latch hole and the

interlock switches area.

• Proper operation of the microwave oven requires that

the magnetron be assembled to the waveguide and
cavity. Never operate the magnetron unless it is
properly installed.

• Be sure that the magnetron gasket is properly

installed around the dome of the tube whenever
installing the magnetron.

2-1

CAUTIONS

Unlike other appliances, the microwave oven is
high-voltage and high-current equipment.
Though it is free from danger in ordinary use,
extreme care should be taken during repair.

THE OVEN IS TO BE SERVICED ONLY
BY PROPERLY QUALIFIED SERVICE
PERSONNEL.

MICROWAVE RADIATION

Personnel should not be exposed to the
microwave energy which may radiate from the
magnetron or other microwave generating
device if it is improperly used or connection.
All input and output microwave connections,
waveguide, flange, and gasket must be secure
never operate the device without a microwave
energy absorbing load attached.
Never look into an open waveguide or antenna
while the device is energized.

Gasket

ANTENNA

COOLING FIN

MAGNETRON
CHASSIS GROUND

FILAMENT
TERMINALS

MAGNETRON

Summary of Contents for 767. 8703000

Page 1: ...Department 731A Toronto BASIC SERVICE MANUAL MODEL 767 8703000 767 8803000 767 8903000 767 8903400 767 8903900 APRIL 2000 FOR MICROWAVE OVEN TECHNICAL FLASH T F 22 432 R ...

Page 2: ...rlock 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 ...

Page 3: ...SCRIPTION 4 3 SERVICE INFORMATION 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 DISASSEMBLY AND ADJUSTMENT 5 3 INTERLOCK CONTINUITY TEST 5 7 COMPONENT TEST PROCEDURE 5 8 TROUBLE SHOOTING 5 11 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 SCHEMATIC DIAGRAM OF P C B 8 1 PRINTED CIRCUIT BOARD 8 2 P C B PARTS LIST 9 1 CONTENTS ...

Page 4: ...tification Rectification Voltage Doubler Half Wave Door Sealing Choke Cover and Choke System Safety Devices Thermostat Open at 90 c 5 c Open at 75 c 5 c Fuse 20A Primary Interlock Switch Secondary Interlock Switch Interlock Monitor Switch Magnetron 2M246 High Voltage Capacitor Capacitor 1 0 µF 2 1 KV AC High Voltage Diode Doide 350 mA 9 0 KV Cavity Lamp 125 V 20 W Tray Tempered Safety Glass Overal...

Page 5: ... operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity Never operate the magnetron unless it is properly installed Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron 2 1 CAUTIONS Unlike other appliances the microwave oven is high voltage and high current equipment Though it is free fro...

Page 6: ...ical parts of the unit Do not install the oven next to a conventional surface unit or above a conventional wall oven 5 Use microwave oven in an ambient temperature less than 104 F 40 C 6 Place the microwave oven on a sturdy and flat surface at least 10 cm 4 inches from the wall 7 Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent interference GROUNDING INSTRUCTI...

Page 7: ...the cooking time LESS Pressing LESS will subtract 10 seconds of cooking time 11 QUICK DEFROST 12 EXPRESS DEFROST 13 NUMBER 14 TIME 15 POWER 16 STOP CLEAR 17 START This feature allows oven to begin functioning OPERATING INSTRUCTIONS Oven Front Plate Window Door Screen Door Seal Display Window Control Panel Door Open Button Safety Door Lock System Turntable Rotating Ring 10 NOTE A beep sounds when a...

Page 8: ...M MICROWAVE RADIATION FIRE E LECTRICAL SHOCK AND HAZARDS WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER S SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM NOTICE SINCE THIS IS BASIC SCHEMATIC DIAGRAM THE VALUES OF COMPONENTS AND SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT ...

Page 9: ...ximately 2100 volts AC is generated in the secondary of the high voltage transformer which is increased by the action of the high voltage diode and charging of the high voltage capacitor The negative 4 000 Volts DC is applied to the filament of the magnetron WHEN THE OVEN IS SET AT ANY LEVEL EXCEPT MAXIMUM The micom controller controls the ON OFF time of relay 2 by the applied signal to vary the a...

Page 10: ...ich is graduated to 600 cc and place the beaker on the center of the turntable Set the energy leakage monitor to 2 450 MHz and use it following the manufacturer s recommended test procedure to assure correct result When measuring the leakage always use the 2 inch 5cm spacer supplied with the probe Operate the oven at its maximum output Measure the microwave radiation using and electromagnetic radi...

Page 11: ...e test probe must be removed no faster than 1 inch sec 2 5 cm sec along the shaded area otherwise a false reading may result The test probe must be held with the grip portion of the handle A false reading may result if the operator s hand is between the handle and the probe When testing near a corner of the door keep the probe perpendicular to the surface making sure the probe horizontally along t...

Page 12: ...s 5 K The microwave power output P in watts is calculated from the following formula 4187 x T T is measured while the microwave generator is operating at full power Magnetron filament heat up time is not included about 3 sec The water is stirred to equalize temperature throughout the vessel prior to measuring the final water temperature Stirring devices and measuring instruments are selected in or...

Page 13: ...TE 1 After replacing the door be sure to check that the primary switch monitor switch and secondary switch operate normally 2 After replacing the door check for microwave energy leakage with a survey meter Microwave energy must be below the limit of 4 mW cm with a 275 ml water load 3 When mounting the door assembly to the oven assembly be sure to adjust the door assembly parallel to the chassis Al...

Page 14: ... the waveguide and the magnetron H HIGH VOLTAGE TRANSFORMER REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from magnetron high voltage transformer and capacitor 3 Remove the screw holding the high voltage transformer to the base plate I FAN MOTOR ASSEMBLY REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from fan motor noise filter and high voltage ...

Page 15: ... tight Make sure the primary monitor and secondary switches operate properly by following the continuity test procedure 5 6 PRIMARY SWITCH ADJUSTMENT DIRECTION MONITOR SWITCH SECONDARY SWITCH K REMOVING THE TURNTABLE MOTOR 1 Remove the glass turntable 2 Remove the rotating ring assʼy by hand 3 Remove the turntable motor cover The turntable base cover is easily removed by pinching the six parts wit...

Page 16: ...losed meter should indicate an closed circuit When the secondary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch C MONITOR SWITCH TEST Disconnect the wire lead from the monitor switch Connect the ohmmeter leads to the common COM and normally closed NC terminals of the switch The meter should indicate closed circuit in the door open...

Page 17: ...ULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Secondary winding Filament winding 2 Measure the resistance Ohm meter scale Rx1000 Primary winding to ground Filament winding to ground 1 Measure the resistance Ohm meter scale Rx1 Filament terminal 2 Measure the resistance Ohm meter scale Rx1000 Fila...

Page 18: ... Terminal to case Measure the continuity Forward Ohm meter scale Rx10000 Measure the continuity Reverse Ohm meter scale Rx10000 Normal Momentarily indicates several ohms and then gradually returns to infinite Normal Infinite Normal Continuity Abnormal Infinite Normal Infinite Abnormal Continuity NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be ...

Page 19: ...OR 1 Disconnect sensor connector from micom computer board 2 Measure resistance terminal to terminal ohm meter scale R X 1000 Normal Approximately BK RD 5 1 Kohm RD WH 2 1 Kohm BK WH 2 1 Kohm Abnormal Infinite or several Sensor cooking condition 1 Oven should be plugged in at least 5 minutes before sensor cooking 2 Room temperature should not exceed 95 F 3 Be sure the exterior of the cooking conta...

Page 20: ... panel to discharge any static charge built up in your body Micom model only CONDITION Microwave oven does not work Inserting many plugs into one outlet and using them at the same time blown fuse or breaker Microwave oven plug is not inserted tightly Output power is too low Low AC input voltage Food temperature is too low Using metallic ware and allowing it to touch the oven wall Sparks occur Inco...

Page 21: ... does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished 5 12 TROUBLE 1 The following visual conditions indicate a probable defective control circuit CONDITION CHECK RESULT CAUSE REMEDY 1 No input can be programmed Continuity No continuity Defective PCB assembly Loose connection Replace PCB assembly Connect them tightly Check the conn ection b...

Page 22: ...of primary switch with door opened Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit Replace fuse Continuity Malfunction of secondary switch Replace fuse primary monitor secondary switches and RELAY RY2 of P C B Assembly No continuity Check continuity of secondary switch with door opened 2 Fuse does not blow No continuity Continuity ...

Page 23: ...ws all figures set but oven does not start cooking while desired program times are set and START pad is touched TROUBLE 4 Oven seems to be operating but little heat is produced in oven load NOTE Simple test of power output conducted by heating one liter water for one min if available Minimum 8 5 C temperature rise is normal condition CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 ...

Page 24: ... relay 2 and check continuity relay 2 Operate the unit Abnormal Defective high voltage capacitor Replace high voltage capacitor Normal Check high vol tage capacitor Abnormal Defective high voltage diode Replace high voltage diode Normal Check high vol tage diode Abnormal Defective magnetron Replace magnetron Check magnetron TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run...

Page 25: ...PARTS LATCH BOARD PARTS CONTROL PANEL PARTS BASE PLATE PARTS SENSOR PARTS 6 1 EXPLODED VIEW INTRODUCTION EV MODEL 767 8703000 767 8803000 767 8903000 767 8903400 767 8903900 MODEL 767 8703000 767 8803000 767 8903000 767 8903400 767 8903900 ...

Page 26: ...A 13213A 13352A 13581A 14970A 14026A 13536A 13552A 13213A 13352A 13581A 13720D 14970A 14026A 15006A 13536A 13720D 13551A for 89034 only DOOR PARTS EV MODEL 767 89034 767 89030 767 89039 MODEL 767 87030 767 88030 ...

Page 27: ... 24781M 26638A 23572A 23550D 24510L 24970A 250201 268711 WTP018 24781M 23550D 24510L 24970A 23551B 268711 WTP018 23551A CONTROL PANEL PARTS EV MODEL 767 87030 767 88030 767 89030 767 89039 MODEL 767 89034 ...

Page 28: ...3052M 340511 36549S WTP013 33390G WTT010 WTT020 WTT021 33112U 35889A 36549S 33052A WTP013 33390G WTT010 WSZ185 33112U 35889A OVEN CAVITY PARTS EV MODEL 767 87030 767 89030 767 89034 767 89039 MODEL 767 88030 ...

Page 29: ...6 5 55262A WTT028 43500A 466003 466001 466001 43501A WSZ085 56912B LATCH BOARD PARTS EV ...

Page 30: ...02 WSZ002 WSZ002 WSZ002 WSZ002 WSZ002 56411A 56930V 56201A 56549F 54974S WTT037 55900A 54810C WTT037 50CZZH 56851D 50FZZA 56324A 56201B For model 767 89034 767 89030 767 89039 767 87030 35012A 34930W INTERIOR PARTS EV ...

Page 31: ...6 7 948503 63302R 56170D WSZ002 WTT021 WTT021 63302L 65006B 65006B 63303L 63303R BASE PLATE PARTS EV ...

Page 32: ...6 8 WTT021 54974T 56501A WTP002 SENSOR PARTS EV ...

Page 33: ...8 1 SCHEMATIC DIAGRAM OF P C B ...

Page 34: ...8 2 PRINTED CIRCUIT BOARD ...

Page 35: ...P NO 3828W5S1535 Printed in Korea ...

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