LG MS-1947C Service Manual
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LG MS-1947C Service Manual

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MICROWAVE OVEN

SERVICE MANUAL
MODEL: MS-1947C
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
May, 2007
Printed in Korea
P/NO : MFL31039005

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  • Page 1: Microwave Oven

    Website http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MS-1947C CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. May, 2007 Printed in Korea P/NO : MFL31039005...

  • 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 MS-1947C Power Requirement 230~240 V / 50 Hz 1200 Watts Single phase, 3 wire grounded Power Output 800 Watts full microwave power (IEC60705) Microwave Frequency 2450 MHz Magnetron 2M214 - 240GP 10 sec. ~ 99 min. 50 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 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 CONTROL PANEL 1. AUTO COOK: Used to cook the foods listed by one touch. 2. AUTO DEFROST: Used to select the auto weight defrost. 3. POWER: Used to select microwave power level for cooking, grill and combi. 4.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE 6. AUTO DEFROST COOKING The following is a description of component functions during oven operation. NUMBER OF AUTO STOP WEIGHT START 1. SETTING THE CLOCK DEFROST (kg) STOP CLOCK NUMBER CLOCK 7. CHILD LOCK This oven has a CHILD LOCK feature TO SET CHILD LOCK NOTE: 1) This is a 24 hour clock.

  • 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 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 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 ±...

  • Page 14: Diode Removal

    D. DOOR GROSS ASSEMBLY REMOVAL E. HIGH VOLTAGE TRANSFORMER REMOVAL 1) Open the door. 2) Pull out the door protector very carefully with a flat- 1) Discharge the high voltage capacitor. blade screwdriver. 2) Disconnect the leadwire from magnetron, high voltage CAUTION : Be careful not to damage door seal plate transformer, and capacitor.
  • Page 15 H. AIR DUCT ASSEMBLY / REMOVAL J. REMOVING THE TURNTABLE MOTOR 1) Disconnect the leadwire from lamp, A.C Relay and 1) Remove the turntable. monitor resistor and magnetron. 2) Remove the turntable shaft VERY CAREFULLY 3) Lay the unit down on its back. 2) Remove the screw to the magnetron cavity.
  • Page 16 K. PCB ASSEMBLY REMOVAL L. INTERLOCK SYSTEM 1) Remove the control panel assembly from the 1) INTERLOCK MECHANISM cavity. (Refer to control panel assembly removal The door lock mechanism is a device which has on previous page.) been specially designed to eliminate 2) Remove screws which hold the PCB SUB ASS’Y to microwave activity when the door is opened during the control panel.

  • 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 FAN MOTOR Measure the resistance. Normal: (Wire leads removed) (Ohm-meter scale: R x 100) A ~ B A ~ C 40 ~ 60Ω 300~500Ω Abnormal: ∞ or several Ω Normal: Approx. 100~200 Ω Measure the resistance. TURNTABLE Abnormal: ∞...

  • 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. assembly oscillation. wire leads from 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

    #EV# EXPLODED VIEW INTRODUCTION MODEL: MS-1947C OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 29 #EV# DOOR PARTS 13581A 13552A 13536A 13213A 14890A 13720D 14026A 14970A...
  • Page 30 #EV# CONTROL PANEL PARTS 24781M 268711 23572A WTT021 23506A...
  • Page 31 #EV# OVEN CAVITY PARTS 33112U WTT021 WTT010 33390G 33052A 36549S 35889A WTP013...
  • Page 32 #EV# LATCH BOARD PARTS WSZ085 466001 43500A 43501A 466003 44510A 466001...
  • Page 33 #EV# INTERIOR PARTS WSZ062 56411A 56930V WSZ002 56324A 50FZZA 56201A WTT028 WTT037 56549F 55900A 54974S WSZ002 56851D WSZ002 50CZZH 56912B 54810C 56901A WTT028 948501 568771 55262A...
  • Page 34 #EV# BASE PLATE PARTS 56170D 63303A 63302A 65006B WTT021 WSZ002...

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