LG MS-72NA Service Manual
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LG MS-72NA Service Manual

LG MS-72NA Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL: MS-72NA
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : 3828W5S1787
Website: http://biz.lgservice.com
NOM
061
Printed in Korea
NYCE
April, 2001

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  • Page 1 Website: http://biz.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MS-72NA CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. NYCE P/NO : 3828W5S1787 April, 2001 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 MS-72NA MODEL 120 Volts AC 60 Hz Power Requirement 1,050 Watts (9,3A) Single phase, 3 wire grounded Power Output 700 Watts full microwave power (IEC60705) Microwave Frequency 2,450 MHz Magnetron 2M213-09 Timer 0 ~ 60 min. Outside Dimensions...

  • 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 Oven Front Plate Window Door Screen Door Seal Timer Knob Control Panel Door Open Button Safety Door Lock System Turntable Rotating Ring OPERATION CHECK After unpacking this appliance, examine the new 2. Place the glass tray inside the oven cavity. oven for evidence of shipping damage.

  • Page 8: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 9: Circuit Description

    CIRCUIT DESCRIPTION • A high voltage of approximately 2100 volts AC is generated in the secondary of the high voltage GENERAL DETAILS transformer which is increased by the action of the high voltage diode and charging of the high voltage •...

  • Page 10: 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 11 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 12: 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 13 D. TIMER MOTOR REMOVAL Remove choke cover cap 1) Remove the control panel assembly from the cavity. (Refer to control panel assembly removal on previous page.) 2) Remove screws which hold the timer motor to the control panel. 3) Removed the timer knob. 4) Remove the door open button.
  • Page 14 F. HIGH VOLTAGE TRANSFORMER I. AIR DUCT ASSEMBLY REMOVAL REMOVAL 1) Disconnect the leadwire from lamp. 2) Remove the mounting screw to Latch Board. 1) Discharge the high voltage capacitor. 2) Disconnect the leadwire from magnetron, high voltage transformer, and capacitor. J.
  • Page 15 K. REMOVING THE TURNTABLE MOTOR L. INTERLOCK SYSTEM 1) Remove the turntable. 1) INTERLOCK MECHANISM 2) Remove the turntable shaft VERY CAREFULLY The door lock mechanism is a device which has with a slotted screwdriver. been specially designed to eliminate completely 3) Lay the unit down on its back.

  • Page 16: 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 17: 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 18 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 19 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 Relay 1 10 sec 12 sec 12 sec...

  • Page 20: 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 21 (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 Check continuity Replace fuse, 1. Fuse blows. Continuity. monitor switch. of monitor primary, monitor, switch (with secondary...
  • Page 22 (TROUBLE 2) Oven seems to be operating but little heat is produced in oven load. CONDITION CHECK RESULT CAUSE REMEDY Lower than 90% of Decrease in power Suggest customer Output is low Check the rating voltage. source voltage contact local power source with load.
  • Page 23 (TROUBLE 3) No microwave oscillation even though oven lamp and fan motor run. CONDITION CHECK RESULT CAUSE REMEDY No microwave Defective timer Replace timer Check the timer No continuity. oscillation. motor. motor. switch of timer motor.(cooking state) Continuity. Check high vol- Defective high Replace high Abnormal...

  • Page 24: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION OUTER CASE INTERIOR BASE PLATE DOOR LATCH BOARD CONTROL PANEL...
  • Page 25 #EV# DOOR PARTS 13581A 13552A 13536A 13213A 13352A 13720D 14026A 14970A...
  • Page 26 #EV# CONTROL PANEL PARTS 24781T 26549T 249401 23572A WTT021 24510L 24970A 250201...
  • Page 27 #EV# OVEN CAVITY PARTS 33112U WTT021 948502 33052A 33390G 34960A 35889A 36549S WTP013...
  • Page 28 #EV# SUCTION GUIDE PARTS 56912B 55262A 43501A 43500A 466001 466003 WTT028 466001 WSZ085...
  • Page 29 #EV# INTERIOR PARTS WSZ062 568771 56411A 56930V 50FZZA WTT028 55006F 56549F 54974S 55900A WTT037 WSZ002 34930W 56324A WSZ002...
  • Page 30 #EV# BASE PLATE PARTS 56170D 54810C WSZ002 63302A 50CZZH 63303A 56851D WTT021 948501 65006B WSZ002 65006B...

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