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LG LTM9020W Service Manual
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LG LTM9020W Service Manual

LG LTM9020W Service Manual

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See also: Owner's Manual , Owner's Manual & Cooking Guide

MICROWAVE OVEN

SERVICE MANUAL
MODEL : LTM9020W/LTM9020B
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.
http://www.lgservice.com

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Summary of Contents for LG LTM9020W

  • Page 1: Microwave Oven

    MICROWAVE OVEN SERVICE MANUAL MODEL : LTM9020W/LTM9020B CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

  • Page 2: Warning To Service Technicians

    CAUTION WARNING TO SERVICE TECHNICIANS 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;...

  • Page 3: Table Of Contents

    FOREWORD Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing yourself to the Microwave Energy normally contained within the oven cavity. MECHANICAL SERVICE INFORMATION TABLE OF CONTENTS 1. Adjustment Procedures ............................3 2.

  • Page 4: Adjustment Procedures

    1. ADJUSTMENT PROCEDURES ADJUST THE LATCH AND SWITCH CLOSING To avoid possible exposure to microwave energy (3) Loosen the two screws holding the plastic latch board as leakage, adjust the door latches and interlock switches, shown. using the following procedure. (4) With the oven door closed tightly, move the latch board ONLY AUTHORIZED SERVICE PERSONNEL upward toward the top of the oven and/or away from the...
  • Page 5 Latch Board Secondary Interlock Switch Interlock Monitor Switch Primary Interlock Switch Figure 1-a LATCH 0-1/64" LATCH BOARD Figure 1-b 0-1/64"...

  • Page 6: Precautions On Installation

    2. PRECAUTIONS ON INSTALLATION 4. TRIAL OPERATION (Figure 2) After installation, the following sequences and results A. Plug the power supply cord into a 120 V AC, 60 Hz, should be checked carefully. single-phase power source with a capacity of at least 20 Microwave Oven amperes.

  • Page 7: Features And Specifications

    5. FEATURES AND SPECIFICATIONS Toaster Microwave Oven A. The safety systems incorporated in this toaster are: A. The safety systems incorporated in this oven are: (1) Toaster door switch (1) Primary interlock switch (2) Toaster thermostat (2) Secondary interlock switch (Note : This thermostat located on the air tunnel will (3) Interlock monitor switch open and stop the unit from operation only if...
  • Page 8 SPECIFICATIONS Rated Power Consumption ..........1350W Output Microwave oven ............900W (*IEC 60705 Rating standard) Adjustable 100W through 900W, 10 steps Toaster ..............800W Frequency ..............2,450 MHz ± 50 MHz Power Supply ...............120V ±12V AC, 60Hz Rated Current...............11.5 Amp. Magnetron & Heater Cooling........Forced Air Cooling Microwave Stirring............Turntable Rectification..............Rectification Voltage Doubler Half-Wave Door Sealing ..............Choke System...

  • Page 9: Overall Circuit Diagram

    6. OVERALL CIRCUIT DIAGRAM A. SCHEMATIC DIAGRAM Figure 3...
  • Page 10 B. MATRIX CIRCUIT FOR TOUCH KEY BOARD Figure 4...

  • Page 11: Operating Procedures

    7. OPERATING PROCEDURES A. OVEN CONTROL PANEL MICROWAVE CONTROL AREA 1. DISPLAY. The Display includes a clock and indicators that tell you time of day, cooking time settings, and cooking functions selected. 2. STOP/CLEAR. Touch this pad to stop the oven or clear entries. 3.
  • Page 12 B. EASY USE TABLE (7) MULTI-STAGE COOKING 1. Touch STOP/CLEAR. MICROWAVE OVEN 2. Touch COOK TIME. (1) KITCHEN TIMER 3. Touch number for cooking time. 1. Touch STOP/CLEAR. 4. Touch POWER. 2. Touch KITCHEN TIMER. 5. Touch number for cooking power level. 3.

  • Page 13: Procedure For Measuring Microwave Energy Leakage

    8. PROCEDURE FOR MEASURING MICROWAVE ENERGY LEAKAGE B. MEASURING MICROWAVE ENERGY LEAKAGE A. CAUTIONS (1) Pour 275 15cc of 20 5°C water in a beaker which is (1) Be sure to check a microwave emission prior to servicing ± ± graduated to 600 cc, and place the beaker in the center the oven if the oven is operative prior to servicing.
  • Page 14 D. MEASUREMENT WITH A FULLY ASSEMBLED OVEN G. POWER OUTPUT MEASUREMENT (1) Fill the test beaker with 59 ˚F(15 ˚C) ~ 75 ˚F(24 ˚C) 1 liter tap (1) After all components, including the outer panels, are water. fully assembled, measure for microwave energy (2) Stir the water in the beaker with thermometer ( ˚F or ˚C) and leakage around the door viewing window, the exhaust measure temperature as T1.

  • Page 15: Disassembly Instructions

    9. DISASSEMBLY INSTRUCTIONS IMPORTANT NOTES: UNIT MUST BE DISCONNECTED FROM ELECTRICAL Remove screw OUTLET WHEN MAKING REPAIRS, RE-PLACEMENTS, ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT securing LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE screw CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED. THE CAPACITOR SHOULD BE DISCHARGED BY USING INSULATED WIRE - I.E.
  • Page 16 C. DOOR GROSS ASSEMBLY REMOVAL Remove choke cover cap (1) Open the door. (2) Remove the choke cover cap very carefully with a flat-blade screwdriver. CAUTION : Be careful not to damage door seal plate by screwdriver. (3) Lift up and push the door. NOTE: 1.
  • Page 17 D. MAGNETRON REMOVAL (Figure 10) E. REMOVING THE TURNTABLE MOTOR (Figure 11) 1) Remove the turntable and rotating ring. (1) Disconnect the wire lead from the magnetron. 2) Lay the unit down on its back. (2) Carefully remove the mounting screws holding the 3) Remove the turntable motor cover.
  • Page 18 F. HIGH VOLTAGE TRANSFORMER REMOVAL I. INTERLOCK SYSTEM 1) Discharge the high voltage capacitor. 1) INTERLOCK MECHANISM 2) Disconnect the leadwire from magnetron, high voltage The door lock mechanism is a device which has been transformer, and capacitor. specially designed to eliminate completely microwave 3) Remove the screw holding the high voltage transformer to activity when the door is opened during cooking and thus the baseplate.

  • Page 19: Interlock Continuity Test

    10. 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 OR V-5230Q FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-62, VP-532A-OF OR V-5220Q FOR MONITOR SWITCH TYPE NO.

  • Page 20: Test And Checkout Procedures, And Troubleshooting

    11. TEST AND CHECKOUT PROCEDURES, AND TROUBLESHOOTING 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 21 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 1. Check DC 9V battery before performing Normal: Approximately 9V CAPACITOR tests.
  • Page 22 COMPONENTS TEST PROCEDURE RESULTS H.V.Diode (rectifer) STEP 1. Test the diode to see if it is shorted. Procedure: 1. Select the Ω scale on the meter. 2. Place the meter leads across the diode as pictured in Figure 14-a. The reading should be “40MΩ,”...

  • Page 23: Test Procedure

    COMPONENTS TEST PROCEDURE RESULTS RELAY 2 1. Measure continuity. POWER 2. Remove the lead wires and operate oven (Power Relay) LEVEL at power level 1 through power level 10. 4 sec 18 sec 6 sec 16 sec 8 sec 14 sec 10 sec 12 sec 12 sec...

  • Page 24: Checkout Procedures

    B. CHECKOUT PROCEDURES (1) CHECKOUT PROCEDURES FOR FUSE BLOWING CAUTION: REPLACE BLOWN FUSE WITH 15 AMPERE FUSE. PROBLEMS CAUSES Fuse blows immediately after Improper operation of the primary interlock, the door is closed. secondary interlock switches and/or the interlock monitor switch. Fuse blows immediately after the door is opened.
  • Page 25 (2) CHECKOUT PROCEDURES FOR RELAY Microwave Oven Toaster - PROBLEM (A) - - PROBLEM (A) - FAN motor and oven lamp turn on without touching FAN motor and indicator light turn on without touching START key when the door is closed. START key when the door is closed.
  • Page 26 (3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD The following symptoms indicate a defective circuit board. (1) The start function fails to operate but the high (4) Some segments of one or more digits do not light up, or voltage Systems, the interlock switches, the door they continue to light up, or segments light when they sensing and the relay check good.

  • Page 27: Troubleshooting

    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 TOASTER AND MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL. CAUTIONS 1.
  • Page 28 (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 29 (TROUBLE 2) Microwave oven does not operate at all, Display window does not display any figures, and no input is accepted. CONDITION CHECK RESULT CAUSE REMEDY Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. monitor switch. primary, monitor of monitor switches, and switch (with...
  • Page 30 (TROUBLE 3) Display shows all figures set, but microwave 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 No continuity. secondary switch. secondary switch.
  • Page 31 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY No microwave Defective PCB Replace PCB Disconnect the No continuity. oscillation. assembly. assembly. wire leads from relay 2 and check continuity Continuity.
  • Page 32 (TROUBLE 6) When toaster operates, strange code can be seen on the display and stop with beep sound. CONDITION CHECK RESULT CAUSE REMEDY Check continuity Defective 1. “F-1” code. No continuity. Replace thermistor of thermistor. thermistor Continuity. Replace toaster Check the No continuity.

  • Page 33: Exploded View

    EXPLODED VIEW INTRODUCTION LATCH BOARD PARTS OVEN CAVITY PARTS INTERIOR PARTS DOOR PARTS BASE PLATE PARTS TOASTER PARTS -32-...

  • Page 34: Door Parts

    DOOR PARTS 13552A 15006A 13581A 13536A 13213A 14890A 14026A 14970A WTP004 268712 13581S 13720D 23506A -33-...

  • Page 35: Oven Cavity Parts

    OVEN CAVITY PARTS WSZ185 33112U 33052A WTT010 WTT020 33390G 34370T 36549S 35889A WTP013 -34-...

  • Page 36: Latch Board Parts

    LATCH BOARD PARTS 43501A WSZ085 56912B 466001 466003 43500A 55262A 466001 44510A -35-...
  • Page 37 OVEN INTERIOR PARTS 568771 WSZ002 56411A 50FZZA 55006F 56930V WTT024 WTT028 56549F 54974S 268711 WSZ002 55900A WTT037 50CZZH WSZ002 56324A 56851D WSZ002 54810C WTT028 -36-...

  • Page 38: Base Plate Parts

    BASE PLATE PARTS 56170D 63302A 63303A 65006A 647781 WTT021 WTT028 WSZ002 WTT021 -37-...
  • Page 39 TOASTER PARTS 753003 739301 749702 753002 753001 75993M 768771 73808A WTT021 76322A 75026C 75264A 749321 76930V 74970A 739302 WTT028 749322 73550A 74970A 73446A 74830A WTT028 74830A 73300A 75026G WTT021 768711 73550L 749701 73550D 466001 74510L 73390M 73550H 73740A 73572A 73720D 73213A 73552A -38-...

  • Page 40: Replacement Parts List

    SCHEMATIC DIAGRAM OF P.C.B. -43-...

  • Page 41: Printed Circuit Board

    PRINTED CIRCUIT BOARD -44-...
  • Page 42 -45-...
  • Page 43 Apr., 2003 P/NO : 3828W5S3279 Printed in Korea...

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