LG MD-0942GT Service Manual
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LG MD-0942GT Service Manual

LG MD-0942GT Service Manual

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Website: http://biz.lgservice.com
MICROWAVE OVEN
SERVICE MANUAL
MODEL: MD-0942GT
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S2388
July., 2002
Printed in Korea

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  • Page 1 Website: http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MD-0942GT CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. P/NO : 3828W5S2388 July., 2002 Printed in Korea...

  • Page 2: Safety Precautions

    SAFETY PRECAUTIONS This device is to be serviced only by properly qualified service personnel. Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to excessive microwave energy. PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY...

  • Page 3: Table Of Contents

    CONTENTS (Page) SAFETY PRECAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Inside front cover SPECIFICATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-1 CAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-1 INSTALLATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-1...

  • Page 4: Specifications

    SPECIFICATIONS ITEM DESCRIPTION MODEL MD-0942GT Power Requirement 120 Volts AC 60 Hz Single phase, 3 wire grounded Microwave 1,250W Toast 550W Power Output 900 Watts full microwave power (IEC60705) Microwave Frequency 2,450 MHz Magnetron 2M214 - 39F Timer 0 ~ 90 min.

  • Page 5: Cautions

    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 6: 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 7: Operating Instructions

    OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal Control Panel Toast Safety Door Lock System Turntable Rotating Ring CONTROL PANEL 1. COOK TIME: Used to cook food for a desired time. 2. CLOCK: Used to set the time of day. 3.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE The following is a description of component functions 7. AUTO WEIGHT DEFROST during oven operation. Desired Parar/ Desired defrost Inicio 1. SETTING THE CLOCK Borrar cooking time category Parar/ Inicio Reloj Set the hour 8. AUTO COOK Borrar Desired Desired Parar/...

  • Page 9: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 10: Circuit Description

    CIRCUIT DESCRIPTION power of microwave oven as POWER LEVEL. GENERAL DETAILS (refer to page 1-1) • The low voltage transformer supplies the necessary • One complete cycle of relay 3 is 22 seconds. voltage to the micom controller when power cord is plugged in.

  • Page 11: 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 12 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 13: 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) + 0.55 X (T ) X M a load of (1000±5) g of potable water.
  • Page 14 D. DOOR GROSS ASSEMBLY REMOVAL F. FAN MOTOR ASSEMBLY REMOVAL 1) Open the door. 1) Discharge the high voltage capacitor. 2) Remove the choke cover very carefully with a flat- 2) Disconnect the leadwire from fan motor, noise filter blade screwdriver. and high voltage capacitor.
  • Page 15 H. AIR DUCT ASSEMBLY REMOVAL J. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable. 1) Disconnect the leadwire from lamp and MGT 2) Remove the turntable shaft VERY CAREFULLY thermostat. with a slotted screwdriver. 2) Remove the mounting screw to the magnetron. 3) Lay the unit down on its back.
  • Page 16 K. PCB ASSEMBLY REMOVAL 1) Remove the control panel assembly from the cavity. (Refer to control panel assembly removal Latch Board on previous page.) 2) Remove screws which hold the PCB SUB ASS’Y to the control panel. 3) Disconnect the flat cable from the PCB SUB Primary Interlock Switch ASS’Y and take off the PCB SUB ASS’Y.

  • Page 17: 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-61 OR VP-531A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH B.

  • Page 18: 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 19 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 20 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 21 COMPONENTS TEST PROCEDURE RESULTS Disconnect the 8 pin Check for P.C.B. connector. Cooking Start connector from P.C.B. (Refer to schemetic diagram) Cooking Start RELAY 3, RELAY 4 Relay 4 OF P.C.B. (Wire leads removed.) Note: Relay Relay 1 Relay 1: Turntable motor Oven lamp Relay 2: Fan motor Relay 3: Microwave...

  • Page 22: Trouble Shooting

    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 23 (TROUBLE 1) The following visual conditions indicate a probable defective control circuit. 1. Incomplete segments. • Segment missing. • Partial segment missing. • Digit flickering (NOTE: Slight flickering is normal.) 2. Colon does not turn on or blink. 3. A distinct change in the brightness of one or more numbers in display. 4.
  • Page 24 (TROUBLE 2) Oven does not operate at all ; Display window does not display any figures and no input is accepted. CONDITION CHECK RESULT CAUSE REMEDY Replace primary Malfunction of the Check continuity 1. Fuse blows. Continuity. and monitor monitor switch. of monitor switches.
  • Page 25 (TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired program times are set and START pad is touched. CONDITION CHECK RESULT CAUSE REMEDY Defective Replace Check continuity 1.Setting time does No continuity. secondary switch. secondary switch.
  • Page 26 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY No microwave Disconnect the Defective P.C.B Replace P.C.B No continuity. oscillation. wire leads from assembly assembly relay 3 and check continuity Continuity.
  • Page 27 (TROUBLE 6) Oven does not cook properly when programmed for the set power level (Operates properly on HIGH) CONDITION CHECK RESULT CAUSE REMEDY Output is full when Defective P.C.B. Replace P.C.B. Disconnect the Abnormal. you set lower assembly. assembly. wire leads from power level.

  • Page 28: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION CONTROL PANEL PARTS LATCH BOARD PARTS OVEN CAVITY PARTS INTERIOR PARTS DOOR PARTS BASE PLATE PARTS TOAST PARTS...
  • Page 29 #EV# DOOR PARTS 13581A 15006A 13536A 13213A 13552A 14026A 14970A 13352A 13720D 13650A...
  • Page 30 #EV# CONTROL PANEL PARTS WTP004 268712 13352A 23506A...
  • Page 31 #EV# OVEN CAVITY PARTS 966  !! 7 !!# ) 966  '"&#! !!!'/ !"!$9 !"!%6 !$#"'5 !#&&') 962!
  • Page 32 #EV# LATCH BOARD PARTS 43501A WSZ085 56912B 466001 WTT028 43500A 55262A 466003 466001 44510A...
  • Page 33 #EV# INTERIOR PARTS 568771 WSZ002 56411A 50FZZA 56930V WTP004 55006F 56549F WTT028 54974S 268711 WSZ002 55900A WTT037 56851D 56324A 50CZZH WSZ002 WSZ002 54810C WTT028...
  • Page 34 #EV# BASE PLATE PARTS 56170D 63302A 63303A 65006A 647781 WSZ002 WSZ002 WTT028 WTT021...
  • Page 35 #EV# TOAST PARTS 76930V 75993M 73572A 73550D 73352A 73740A 743501 73552A 73390M 73213A 73550H 73720D...

  • Page 36: Schematic Diagram Of P.c.b

    SCHEMATIC DIAGRAM OF P.C.B...

  • Page 37: Printed Circuit Board

    PRINTED CIRCUIT BOARD KEY P.C.B. MAIN P.C.B.

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