LG MH-1144DP Service Manual
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LG MH-1144DP Service Manual

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삼
삼
흥
흥
정
정
판
판
MICROWAVE OVEN
SERVICE MANUAL
MODEL: MH-1144DP
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S5177
Website http://biz.lgservice.com
March, 2005
Printed in Korea

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  • Page 1 삼 삼 흥 흥 정 정 판 판 Website http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MH-1144DP CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. March, 2005 P/NO : 3828W5S5177 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 MH-1144DP Power Requirement 120 Volts AC 60 Hz Microwave 1400W Grill 1000W Single phase, 3 wire grounded Power Output 1000 Watts full microwave power (IEC60705) Microwave Frequency 2450 MHz Magnetron 2M246 - 050GF Timer 0 ~ 99 min. 99 sec...

  • 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 GROUNDING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with For personal safety, this appliance must be fully a soft, damp cloth. Check for damage such as grounded at all times.

  • Page 7: Operating Instructions

    OPERATING INSTRUCTIONS FEATURES Grill Rack Rotating Ring CONTROL PANEL 1. INDICATORS 2. LATIN MENU 3. OPTION 4. NUMBER: Used to set for time of day, cooking time, power level or defrost weight. 5. AUTO DEFROST: Used to select the desired auto weight defrost programmed with weight pad.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE The following is a description of component functions during oven operation. 7. AUTO WEIGHT DEFROST COOKING 1. SETTING THE CLOCK AUTO DESCONG NUMBER OF PAUSA/BORRAR NUMBER PAUSA/BORRAR RELOJ NUMBER RELOJ POR PESO WEIGHT ex.) To set 4:30, touch number key [4],[3], and [0]. NOTE: 1) This is a 12 hour clock.

  • Page 9: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 10: Circuit Description

    CIRCUIT DESCRIPTION GENERAL DETAILS power of microwave oven as POWER LEVEL. (refer to page 1-1) • The low voltage transformer supplies the necessary voltage to the micom controller when power cord is WHEN THE DOOR IS OPENED DURING plugged in. COOKING •...

  • Page 11: Service Information

    SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY MEASURING INSTRUMENTS NECESSARY TOOLS Tools normally used for TV servicing are sufficient. • TESTER (VOLTS-DC, AC, Ohmmeter) Standard tools are listed below. • Microwave survey meter - Holaday HI-1500 • Diagonal 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) a load of (1000 ±...
  • Page 14 D. PCB ASSEMBLY REMOVAL Remove choke cover 1) Remove the control panel assembly from the cavity. (Refer to control panel assembly removal on previous page.) 2) Remove screws which hold the PCB SUB ASSEMBLY to the control panel. 3) Disconnect the flat cable from the PCB SUB ASSEMBLY and take off the PCB SUB ASSEMBLY.
  • Page 15 F. MAGNETRON REMOVAL G. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable and rotating ring. 1) Disconnect the leadwire 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. magnetron and the waveguide.
  • Page 16 H. HIGH VOLTAGE TRANSFORMER K. INTERLOCK SYSTEM REMOVAL 1) INTERLOCK MECHANISM The door lock mechanism is a device which has 1) Discharge the high voltage capacitor. been specially designed to eliminate completely 2) Disconnect the leadwire from magnetron, high voltage microwave activity when the door is opened during transformer, and capacitor.

  • 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-62 OR VP-532A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH A.

  • 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...
  • Page 20 COMPONENTS TEST PROCEDURE RESULTS HEATER ELEMENT Measure the resistance. Normal: (Wire leads removed.) (Multi-meter scale:RX1) Gill heater Approx.15 Ω (at 20-30 Normal: Measure the resistance with 500V-100M more than 1.0M Ω Ohm insulation resistance meter. NOTE: Make sure heater is fully cooled when tested. THERMOSTAT 0°C~Approx 110°C Over 180°C...
  • Page 21 COMPONENTS TEST PROCEDURE RESULTS RELAY 2 Check for continuity of relay 2 with an POWER ohm-meter. LEVEL (Remove wire leads from relay 2 and operate the unit.) 4 sec 18 sec 6 sec 16 sec 8 sec 14 sec 10 sec 12 sec 12 sec 10 sec...

  • 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 Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. monitor switch. primary, monitor of monitor secondary switch (with...
  • 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 Replace Defective Check continuity 1.Setting time No continuity. secondary switch. secondary switch. of secondary does not count switch (with...
  • 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 Defective PCB Replace PCB Disconnect the No continuity. assembly. oscillation. assembly. wire leads from relay 2 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 Defective P.C.B. Replace P.C.B. Output is full when Disconnect the Abnormal. assembly. assembly. you set lower wire leads from power level.

  • Page 28: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION...
  • Page 29 #EV# DOOR PARTS 15006A 13581A 13552A 13536A 13213A 14890A 13720D 14026A 14970A...
  • Page 30 #EV# CONTROL PANEL PARTS 24781M 23572A 268711 WTP018 23506A 24510L 24970A 250201...
  • Page 31 #EV# OVEN CAVITY PARTS WNH001 33808A WTT021 33112U 44360A 34810H 34810H 33052M WTT010 35026G 33390G 34370T 35300A 36549S 35889A WTP013...
  • Page 32 #EV# LATCH BOARD PARTS WSZ085 466001 43500A 466003 466001...
  • Page 33 #EV# INTERIOR PARTS 568771 WSZ002 56411A 50FZZA 349301 56930V 55006F WTT028 56549F 54974S WEB001 55900A WTT037 WSZ002 349302 WSZ002 56324A 50CZZH 56851D WEB001 WSZ002 56912B 948501 54810C WTT028 55262A...
  • Page 34 #EV# BASE PLATE PARTS 56170D 63303A 63302A 948502 647781 WTT030 WSZ002 WTT021...

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