LG MB-393T Service Manual
  1. Manuals
  2. Brands
  3. LG Manuals
  4. Microwave Oven
  5. MB-393T
  6. Service manual
LG MB-393T Service Manual

LG MB-393T Service Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
MICROWAVE OVEN
SERVICE MANUAL
MODEL : MB-393T
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

Advertisement

Table of Contents
loading

Related Manuals for LG MB-393T

Summary of Contents for LG MB-393T

  • Page 1 MICROWAVE OVEN SERVICE MANUAL MODEL : MB-393T 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 MB-393T Power Requirement 230 Volts AC 50 Hz Single phase, 3 wire grounded Microwave 1,200W Grill 1,100W Combi 2,250W Power Output 800 Watts full microwave power (IEC705) Microwave Frequency 2,450 MHz Magnetron 2M214 - 39F, 2M218J, 2M254J Timer 60 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 Turntable Grill Rack Rotating Ring CONTROL PANEL Watt 1. POWER CONTROL KNOB: Used in selected the desired power level for cooking. 2. TIMER KNOB: Used to set the cooking time. 3.

  • Page 8: Operating Sequence

    OPERATING SEQUENCE GRILL COOKING MICROWAVE COOKING 1. Open the oven door, place the food on the rack in 1. Open the oven door, place the food on the the oven, and close the oven door. turntable in the oven, and close the oven door. 2.

  • Page 9: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 10: Circuit Description

    CIRCUIT DESCRIPTION • As the door is closed, the contact of MONITOR WHEN THE DOOR IS OPENED DURING SWITCH opens. This switch creates the short circuit to COOKING blow fuse during operation under abnormal condition. • Both primary switch and secondary switch open to cut (ie, should the contacts of primary and secondary off the primary winding voltage to the high voltage switch fail to open the circuit)

  • 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) + 0.88 X (T ) X M a load of (1000±5) g of potable water.
  • Page 14 D. DOOR GROSS ASSEMBLY REMOVAL E. HIGH VOLTAGE TRANSFORMER 1) Open the door. REMOVAL 2) Remove the choke cover cap very carefully with a 1) Discharge the high voltage capacitor. flat-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. 1) Remove the turntable. 2) Remove the Rotating Ring. 2) Remove the mounting screw to Latch Board. 3) Lay the unit down on its back. 4) Remove the turntable motor cover.
  • Page 16 K. TIMER MOTOR REMOVAL L. INTERLOCK SYSTEM 1) Remove the control panel assembly from the 1) INTERLOCK MECHANISM cavity. The door lock mechanism is a device which has 2) Remove screws which hold the timer motor to the been specially designed to eliminate completely 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 TIMER MOTOR Check for continuity of timer motor with an Turn On Turn Off (Wire leads removed) ohm-meter. (Remove wire leads from timer motor) Approx. 22 KΩ Grill Switch Microwave Switch Note : A is timer ON, OFF switch.

  • 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) Oven lamp does not turn on when the timer knob is pushed with door closed. CONDITION CHECK RESULT CAUSE REMEDY Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. monitor switch. primary, monitor of monitor and secondary switch (with switches.
  • Page 24 CONDITION CHECK RESULT CAUSE REMEDY No continuity. Check the Malfunction of the replace. continuity of the timer switch. timer switch contacts. Check the No continuity. continuity of the Faulty thermostat. replace. thermostat. (TROUBLE 3) Output power is low. CONDITION CHECK RESULT CAUSE REMEDY...
  • Page 25 (TROUBLE 5) Oven does not cook at all even though turntable rotates. CONDITION CHECK RESULT CAUSE REMEDY No microwave Replace the power Malfunction of the Check the No continuity. oscillation. control switch. power control power control switch. switch(cooking state). Continuity. Defective monitor Check the Abnormal or burn...

  • Page 26: Exploded View

    EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 27 DOOR PARTS !#&) !## ) !#!$) ! !) !!# ) !% , " $) "'%) !$#)
  • Page 28 CONTROL PANEL PARTS 24781T 26549T 249401 23572A WTP004 249402...
  • Page 29 OVEN CAVITY PARTS WTT021 33112U WTT021 35264A 33550H WNZ015 33052M 340511 35026G 35300S 33390G 34990A 35889A 36549S WTP013...
  • Page 30 LATCH BOARD PARTS WSZ085 466001 43501A 43500A 466003 44510A 466001...
  • Page 31 INTERIOR PARTS 568771 WSZ062 56411A 56930V 56930G 34930W 50FZZA WTT028 56201A 56549F 54974S WSZ002 55900A WTT037 56912B WSZ002 50CZZH 56851C 55262A WTT028 54810C 56324A WSZ002...
  • Page 32 BASE PLATE PARTS 56170D 63302A 63303A 948501 WTT021 65006B WSZ002...

Table of Contents