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LG MB-392AA Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL : MB-392AA
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

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Summary of Contents for LG MB-392AA

  • Page 1 MICROWAVE OVEN SERVICE MANUAL MODEL : MB-392AA CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

  • Page 2: Service Information

    SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. • TESTER(VOLTS-DC, AC., Ohmmeter) Standard tools are listed below. • Microwave survey meter • Diagonal pliers - Holaday HI-1500 • Long nose pliers HI-1501 •...

  • Page 3: Measurement With Outer Case Removed

    MEASUREMENT WITH OUTER CASE NOTES WHEN MEASURING REMOVED • Do not exceed meter full scale deflection. • The test probe must be removed no faster than • When you replace the magnetron, measure for 1 inch/sec (2.5 cm/sec) along the shaded area, microwave energy leakage before the outer case is otherwise a false reading may result.

  • Page 4: Measurement Of Microwave Power Output

    MEASUREMENT OF MICROWAVE POWER OUTPUT • Microwave power output measurement is made with • The microwave power output P in watts is calculated the microwave oven supplied at its rated voltage and from the following formula : operated at its maximum microwave power setting with 4187 X (∆T) + 0.88 X (T ) X M a load of (1000±5) g of potable water.

  • Page 5: Fan Motor Assembly Removal

    D. DOOR GROSS ASSEMBLY REMOVAL E. HIGH VOLTAGE TRANSFORMER 1) Open the door. REMOVAL 2) Remove the choke cover cap very carefully with a 1) Discharge the high voltage capacitor. flat-blade screwdriver. 2) Disconnect the leadwire from magnetron, high voltage CAUTION : Be careful not to damage door seal plate transformer, and capacitor.

  • Page 6: Magnetron Removal

    H. AIR DUCT ASSEMBLY REMOVAL J. REMOVING THE TURNTABLE MOTOR 1) Disconnect the leadwire from lamp. 1) Remove the turntable. 2) Remove the Rotating Ring. 2) Remove the mounting screw to Latch Board. 3) Lay the unit down on its back. 4) Remove the turntable motor cover.
  • Page 7 K. TIMER MOTOR REMOVAL L. INTERLOCK SYSTEM 1) Remove the control panel assembly from the 1) INTERLOCK MECHANISM cavity. The door lock mechanism is a device which has 2) Remove screws which hold the timer motor to the been specially designed to eliminate completely control panel.

  • Page 8: Interlock Continuity Test

    INTERLOCK CONTINUITY TEST WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS. TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-62 OR VP-532A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH B.

  • Page 9: Component Test Procedure

    COMPONENT TEST PROCEDURE CAUTIONS 1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.
  • Page 10 COMPONENTS TEST PROCEDURE RESULTS Antenna Gasket Chassis Filament NOTE: When testing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. HIGH VOLTAGE Measure the resistance. Normal: Momentarily indicates CAPACITOR (Ohm-meter scale: Rx1000) several ohms, and then...
  • Page 11 COMPONENTS TEST PROCEDURE RESULTS FUSE Check for continuity of the fuse with an Normal Abnormal multi-meter. NOTE: If the fuse is blown, check the primary, the secondary, and the monitor switches, H.V.D. and H.V.C. before replacing the fuse. If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time.
  • Page 12 COMPONENTS TEST PROCEDURE RESULTS TIMER MOTOR Check for continuity of timer motor with an Turn On Turn Off (Wire leads removed) ohm-meter. (Remove wire leads from timer motor) Grill Microwave Approx. 22 KΩ Note : A is timer ON, OFF switch.

  • Page 13: Troubleshooting

    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.
  • Page 14 (TROUBLE 1) Oven lamp does not turn on when the timer knob is pushed with door closed. CONDITION CHECK RESULT CAUSE REMEDY Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. monitor switch. primary, monitor of monitor and secondary switch (with switches.
  • Page 15 CONDITION CHECK RESULT CAUSE REMEDY No continuity. Check the Malfunction of the replace. continuity of the timer switch. timer switch contacts. Check the No continuity. continuity of the Faulty thermostat. replace. thermostat. (TROUBLE 3) Output power is low. CONDITION CHECK RESULT CAUSE REMEDY...
  • Page 16 (TROUBLE 5) Oven does not cook at all even though turntable rotates. CONDITION CHECK RESULT CAUSE REMEDY No microwave Replace the power Malfunction of the Check the No continuity. oscillation. control switch. power control power control switch. switch(cooking state). Continuity. Check the Abnormal or burn Defective monitor...

  • Page 17: Microwave Radiation

    CAUTIONS Unlike other appliances, the microwave oven is MICROWAVE RADIATION high-voltage and high-current equipment. Personnel should not be exposed to the Though it is free from danger in ordinary use, microwave energy which may radiate from the extreme care should be taken during repair. magnetron or other microwave generating device if it is improperly used or connection.

  • Page 18: Installations

    INSTALLATIONS BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. INSTALLING EARTHING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with This microwave oven is designed to be used in a fully a soft, damp cloth. Check for damage such as earthed condition.

  • Page 19: Exploded View

    EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...

  • Page 20: Door Parts

    DOOR PARTS 13581A 15006A 13536A 13552A 13213A 13720D 13352A 14026A 14970A...

  • Page 21: Control Panel Parts

    CONTROL PANEL PARTS 23572A 249402 26549T WTP015 249401 969201 24781T...

  • Page 22: Oven Cavity Parts

    OVEN CAVITY PARTS WTT021 33112U WTT021 35264A 33550H WNZ015 33052M 340511 35026G 33390G 35300S 34960A 35889A 34036W 36549S WTP013...

  • Page 23: Latch Board Parts

    LATCH BOARD PARTS WSZ085 466001 43501A 43500A 466003 44510A 466002...

  • Page 24: Interior Parts

    INTERIOR PARTS 568771 WSZ062 56411A 56930V 56930G 50FZZA WTT028 56201A 56549F 54974S WSZ002 55900A WTT037 56851D 56912B WSZ002 50CZZH 56851C 55262A WTT028 54810C 56324A WSZ002 56201B...

  • Page 25: Base Plate Parts

    BASE PLATE PARTS 56170D 63302A 63303A WTT021 65006B WSZ002...

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