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C. TROUBLE SHOOTING

WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF THE
FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE MICROWAVE
OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL.

CAUTIONS

1. Check grounding before checking for trouble.
2. Be careful of the high voltage circuit.
3. Discharge the high voltage capacitor.
4. When checking the continuity of the switches or the high voltage transformer, disconnect one lead wire from these

parts and then check continuity with the AC plug removed. Otherwise it may result in a false reading or damage to
your meter.

5. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel.

Always touch yourself to ground while working on this panel to discharge any static charge built up in your body.
(Micom model only)

-26-

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.

Inconsistent intensity of
microwave by their
characteristics.

1. Use plastic wrap or lid.
2. Stir once or twice while

cooking soup, cocoa or
milk, etc.

Uneven cooking.

Ceramic ware trimmed in
gold or silver powder is used.

Avoid using other electrical
appliances when you use the
microwave oven.

Insert microwave oven plug
securely.

Use the microwave oven at
adequate line voltage.

This may not be a defect.
It is possible that the food
should be cooked for a
longer time period.

Do not use metallic ware for
cooking except that noted in
the cooking guide.

Do not use any type of
cookware with metallic
trimming.

CAUSE

REMEDY

Summary of Contents for 721.66312500

Page 1: ...DIVISION 20 BASIC FIELD MANUAL FOR MICROWAVE OVEN MODEL 721 66312500 721 66319500 July 2005 MODEL 721 66312 721 66319...

Page 2: ...per 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 repaired or adj...

Page 3: ...ustment Procedures 3 2 Precautions on Installation 5 3 General Precautions in Use 5 4 Trial Operation 5 5 Specifications 6 6 Overall Circuit Diagram 7 8 7 Operating Procedures 9 11 8 Procedure for Mea...

Page 4: ...step 3 and follow all steps in order ADJUST THE LATCH AND SWITCH CLOSING 3 Loosen the two screws holding the plastic latch board as shown 4 With the oven door closed tightly move the latch board upwar...

Page 5: ...4 LATCH BOARD MONITOR INTERLOCK SWITCH PRIMARY INTERLOCK SWITCH SECONDARY INTERLOCK SWITCH LATCH LATCH BOARD 0 1 64 0 1 64 A B DOOR LATCH Figure 1 a Figure 1 b...

Page 6: ...avity light comes on The unit will begin cooking and the display window will show the time counting down by seconds E After about 5 minutes make sure the primary interlock switch the secondary interlo...

Page 7: ...nterlock Switch Interlock Monitor Magnetron 2M246 050GF High Voltage Capacitor Capacitor 0 95 F 2 1KV Ac High Voltage Diode 350mA 9 0KV Cavity Lamp 125V 20W Timer Digital up to 99 mm 99 sec in each co...

Page 8: ...OTECTION FROM MICROWAVE RADIATION FIRE ELECTRICAL 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 T...

Page 9: ...8 B MATRIX CIRCUIT FOR TOUCH KEY BOARD Figure 4...

Page 10: ...7 OPERATING PROCEDURES A OVEN CONTROL PANEL NOTE A beep sounds when you touch a key on the control panel to indicate that you have entered a setting 9 Figure 5...

Page 11: ...time power level quantities or weights 5 COOK TIME Touch this pad to set a cooking time 6 CLOCK Touch this pad to enter the time of day 7 STOP CLEAR Touch this pad to stop the oven or clear entries a...

Page 12: ...ing time 4 Touch POWER 5 Touch number for cooking power level 6 Touch START 6 MULTI STAGE COOKING 1 Touch STOP CLEAR 2 Touch COOK TIME 3 Touch numbers for cooking time 4 Touch POWER 5 Touch number for...

Page 13: ...q And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NOTE The standard is 5mW cm sq while in the customer s home 1mW cm sq stated here is ma...

Page 14: ...information on the service invoice 2 Should the microwave energy leakage not be more than 1mW cm sq after determining that all parts are in good condition functioning properly and genuine replacement...

Page 15: ...s 8 1 Remove three screws from the rear section 2 Remove one screw from the side section 3 Push the outer case back about 1 inch 3cm 4 Lift the case from the set B REMOVING POWER AND CONTROL CIRCUIT B...

Page 16: ...e normally 2 After replacing the door check for microwave energy leakage with a survey meter Microwave energy must be below the limit of 5 mW cm sq with a 275 ml water load 3 When mounting the door as...

Page 17: ...eter around the magnetron Microwave energy must be below the limit of 5 mW cm2 With a 275 ml water load Make sure that gasket is rigidly attached to the magnetron To prevent microwave leakage tighten...

Page 18: ...e the two screws holding the fan motor assembly to the suction guide ass y G HIGH VOLTAGE TRANSFORMER REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the wire lead from the magnetron the h...

Page 19: ...CHANISM The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting...

Page 20: ...6 FA 63 OR VP 533A OF FOR SECONDARY SWITCH B SECONDARY INTERLOCK SWITCH TEST Disconnect the wire lead from the secondary switch Connect the ohmmeter leads to the common COM and normally open NO termin...

Page 21: ...VEN HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Select the scale on the meter Primary winding Secondary winding Filament winding 2 Measure the res...

Page 22: ...items as illustrated in figures Terminal to terminal Terminal to case Check for continuity of relay 2 with an ohm meter Remove wire leads from relay 2 and operate the unit POWER LEVEL 1 2 3 4 5 6 7 8...

Page 23: ...2 This has the positive side of the battery connected to the cathode of the diode 3 The diode should be forward biased therefore a voltage reading of approximately 4 7 VDC to 6 4 VDC will be read dep...

Page 24: ...WITH 20 AMPERE FUSE NOTES If the fuse is blown by an improper switch operation replace the defective switches and the fuse at the same time After replacing the defective switches with new ones make su...

Page 25: ...ector of I O CON from the circuit board Does the unit still operate Replace the circuit board NO YES NO PROBLEM B FAN motor and oven lamp turn on When the door is closed and START key is touched GOOD...

Page 26: ...ormal relay continuously operates 3 The buzzer does not sound or continues to sound NOTE A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON 4 Some segmen...

Page 27: ...charge any static charge built up in your body Micom model only 26 CONDITION Microwave oven does not work Inserting many plugs into one outlet and using them at the same time blown fuse or breaker Mic...

Page 28: ...me while counting down 9 Display counts down too fast while cooking 10 Each indicator light does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finish...

Page 29: ...No continuity Normal Defective high voltage capacitor Replace high voltage capacitor Fuse blows again Defective high volt age transformer Replace high volt age transformer Malfunction of the monitor s...

Page 30: ...Replace oven lamp Loose connection Connect them tightly CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 of rating voltage Normal Normal Abnormal Abnormal Measure the output power Disco...

Page 31: ...capacitor Replace high voltage capacitor Check high vol tage capacitor Abnormal Defective magnetron Replace magnetron Check magnetron TROUBLE 5 No microwave oscillation even though oven lamp and fan m...

Page 32: ...31 DOOR PARTS CONTROL PANEL PARTS BASE PLATE PARTS OVEN CAVITY PARTS LATCH BOARD PARTS INTERIOR PARTS SENSOR PARTS EV EXPLODED VIEW INTRODUCTION Model 721 66312500 721 66319500...

Page 33: ...32 1001 1000 1004 1002 1006 1007 1005 1003 EV DOOR PARTS...

Page 34: ...33 2000 2002 2006 W106 2004 2381 EV CONTROL PANEL PARTS...

Page 35: ...34 3034 3003 W105 3009 3002 3008 3001 W103 W118 W107 For model 721 66312 For model 721 66319 EV OVEN CAVITY PARTS...

Page 36: ...35 W102 4003 5015 4002 4002 4000 EV LATCH BOARD PARTS...

Page 37: ...36 5001 W101 5010 5041 5014 5016 3006 W102 5003 5012 W110 5000 5040 W101 5002 W208 5018 W109 W101 W208 5007 5009 EV INTERIOR PARTS...

Page 38: ...37 W101 W108 6007 5008 6000 6001 EV BASE PLATE PARTS...

Page 39: ...P NO 3828W5S5264 Printed in Korea...

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