LG MH-657PL Service Manual
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LG MH-657PL Service Manual

LG MH-657PL Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL: MH-657PL
CAUTION
BEFORE SERVICING THE UNIT, READ
THE SAFETY PRECAUTIONS IN THIS MANUAL.

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Summary of Contents for LG MH-657PL

  • Page 1 MICROWAVE OVEN SERVICE MANUAL MODEL: MH-657PL CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

  • 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-657PL Power Requirement 230 Volts AC 50 Hz Single phase, 3 wire grounded Microwave 1,300W Gril 1,250W Combination 2,500W Power Output 900 Watts full microwave power (IEC60705) Microwave Frequency 2,450 MHz Magnetron 2M214 - 39F Timer 0 ~ 99 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 Safety Door Lock System Cook Tray Turntable Rotating Ring CONTROL PANEL 1. INDICATORS 2. DIAL AUTO COOK: Used to cook the foods listed by one touch. LESS/MORE: Used to change cooking time. WEIGHT: Used to select the desired weight.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE 8. CHILD LOCK The following is a description of component functions during oven operation. This oven has a CHILD LOCK feature • TO SET CHILD LOCK 1. CANCEL FUNCTION • Touch the Stop Touch the pad whenever you need to STOP •...

  • 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 2 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) 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-62 OR VP-532A-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 2, RELAY 3 Relay 3 OF P.C.B. (Wire leads removed.) Note: Relay Relay 1 Relay 1: Fan motor Turntable motor Oven lamp Relay 2: 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 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 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

    EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 29 DOOR PARTS 15006A 13581A 13552A 13213A 14890A 13720D 14026A WTP004 14970A 136502 136501...
  • Page 30 CONTROL PANEL PARTS 24781S WTP004 268711 268712 23572A 249401 23806C 26638A 250201...
  • Page 31 OVEN CAVITY PARTS WTT021 33808A WTT021 33112U 948501 WTT028 WSZ094 33052M WTT020 33035A 343501 35300S 344702 33390G 34810A 466003 34370T 348102 36549H 348102 344701 35889A 368771 36549S 346810 WTP013...
  • Page 32 LATCH BOARD PARTS WSZ085 43501A 466001 466003 44510A 466001 43500A...
  • Page 33 INTERIOR PARTS 33550H 34810H 568771 34930W WTT021 343502 50FZZA WSZ002 WTT021 56411A WTP004 WTT037 56201A 54975G 56549F 56322V WTT028 55900A 54974S WSZ002 WSZ002 50CZZH 56324A WSZ002 56851D 56912B 54810C 56930M WSZ002 WTT028 948504 55262A...
  • Page 34 BASE PLATE PARTS 56170D 63302A WTT021 647781 948503 WTT030 WSZ002 WTT021 63303A...

  • Page 35: Replacement Parts List

    REPLACEMENT PARTS LIST LOC. PART NO. DESCRIPTION ALTER VENDOR 13213A 3213W1A032L DOOR FRAME ASSY 13552A 3552W1A042A CHOKE COVER 13581A 3581W1A291B DOOR ASSEMBLY 136501 3650W2A029E HANDLE,[DOOR HANDLE] 136502 3650W2A030A HANDLE,[DOOR HANDLE] 13720D 3720W0D154H PANEL,[DOOR] 14026A 4026W2A015A LATCH 14890A 4890W1A006V GLASS 14970A 4970WRA001C SPRING 15006A...
  • Page 36 LOC. PART NO. DESCRIPTION ALTER VENDOR 56170D 6170W1D029C TRANSFORMER,HIGH VOLTAGE 56201A 6201W2A021E FILTER ASSEMBLY(CIRC) 56324A 2B71732B MAGNETRON 56411A 6411W1A001G POWER CORD ASSY 56549F 6549W1F005A MOTOR(CIRC),FAN 6549W1F007A 56851D 6851W1A001A CABLE ASSEMBLY 568771 6877W1A341A HARNESS 56912B 6912W3B002D LAMP,DRAWING 56930M 6930WRT003B THERMOSTAT 6930WRT004B 56930V 6930W1A001F THERMOSTAT...

  • Page 37: Schematic Diagram Of P.c.b

    SCHEMATIC DIAGRAM OF P.C.B...

  • Page 38: Printed Circuit Board

    PRINTED CIRCUIT BOARD...

  • Page 39: P.c.b. Parts List

    P.C.B. PARTS LIST LOC. PART NO DESCRPTION SPECIFICATION ALTER VEND BLED 0DLZW5A009D LED OASIS TOA-B11CEYG-B2-D BK YELLOW-GREEN 1 BZ1 6908W3YA01A BUZZER GPB-B-26B2 SUNJIN 1ES(EXTERNAL) NONE C01 0CK1040H518 CAPACITOR,FIXED CERAMIC(High dielectric) 0.1UF D 25V 10% B(Y5P) TA26 C02 0CE6871H618 CAPACITOR,FIXED ELECTROLYTIC 680000000PF SM,SA 25V 20% FL TP 5 C03 0CE6871H618 CAPACITOR,FIXED ELECTROLYTIC 680000000PF SM,SA 25V 20% FL TP 5...
  • Page 40 LOC. PART NO DESCRPTION SPECIFICATION ALTER VEND Q110 0TR127009AA TRANSISTOR,BIPOLARS KTA1270-Y (KTA562TM) TP KEC - - Q111 0TR127009AA TRANSISTOR,BIPOLARS KTA1270-Y (KTA562TM) TP KEC - - Q112 0TR127009AA TRANSISTOR,BIPOLARS KTA1270-Y (KTA562TM) TP KEC - - Q113 0TR127009AA TRANSISTOR,BIPOLARS KTA1270-Y (KTA562TM) TP KEC - - Q20 0TR107009AD TRANSISTOR,BIPOLARS KRC 107M TP KEC - - Q31 0TR105009AB TRANSISTOR,BIPOLARS...
  • Page 41 RY3 6920W2D010A RELAY OJ-SS-112LM ORIGNAL DC12V 16.7mA 720 Ohm RY4 6920W5A012B RELAY G5G-1A-DT1-LG(1.5MS) OMRON DC12V 4.7mA 1 6920W5A012A RY5 6920W5A012A RELAY G5G-1A-DT1-LG OMRON DC12V 41.7mA 250V 16 SW1 3Q60020A SWITCH,TACT SKHV10910 G/S ALPS NONE NONE UL. CSA SW10 3Q60020A SWITCH,TACT SKHV10910 G/S ALPS NONE NONE UL.
  • Page 42 August, 2001 P/NO : 3828W5S1990 Printed in Korea...

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