LG MAB745W 01 Service Manual

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MICROWAVE OVEN

SERVICE MANUAL
MODEL: MAB745W
MAB745B
CAUTION
BEFORE SERVICING THE UNIT,READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
May, 2004
P/NO : 3828W5S3839
Printed in Korea

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Summary of Contents for LG MAB745W 01

  • Page 1: Microwave Oven

    Website http://us.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MAB745W MAB745B CAUTION BEFORE SERVICING THE UNIT,READ THE SAFETY PRECAUTIONS IN THIS MANUAL. May, 2004 P/NO : 3828W5S3839 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 MAB745W / MAB745B Power Requirement 120 Volts AC 60 Hz 950 Watts (9.0A) Single phase, 3 wire grounded Power Output 700 Watts full microwave power (IEC60705) Microwave Frequency 2450 MHz Magnetron 2M214-39F Timer 0 ~ 9 min. 99 sec. 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 For personal safety,this appliance must be fully 1. Empty the microwave oven and clean inside it with grounded at all times. a soft, damp cloth. Check for damage such as misaligned door, damage around the door or dents In the event of an electrical short circuit, grounding inside the cavity or on the exterior.
  • Page 7: Operating Instructions

    OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal Display Window Control Panel Safety Door Lock System Turntable Roller rest CONTROL PANEL 1. INDICATORS 2. ONE TOUCH CONTROL: Used to cook the foods listed by one touch. 3. AUTO DEFROST: Used to select the desired auto weight defrost programmed with weight pad.
  • Page 8: Operating Sequence

    OPERATING SEQUENCE 6.MULTI-STAGE COOKING The following is a description of component functions during oven operation. 1ST STAGE 1. SETTING THE CLOCK STOP/CLEAR TIME NUMBER POWER STOP/CLEAR CLOCK NUMBER CLOCK NUMBER ex.) To set 4:30,touch number key [4 ],[3 ], and [0 ]. 2ND STAGE NOTE: 1) This is a 12 hour clock.
  • Page 9: Schematic Diagram (I)

    SCHEMATIC DIAGRAM (I) *Check the Rating Model No.
  • Page 10: Schematic Diagram (Ii)

    SCHEMATIC DIAGRAM (II) *Check the Rating Model No. (ADD Noise filter)
  • Page 11: Circuit Description

    CIRCUIT DESCRIPTION • A high voltage of approximately 2100 volts AC is GENERAL DETAILS generated in the secondary of the high voltage • The low voltage transformer supplies the necessary transformer which is increased by the action of the high voltage to the micom controller when power cord is voltage diode and charging of the high voltage plugged in.
  • Page 12: 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) • Microwave survey meter Standard tools are listed below. - Holaday HI-1500 • Diagonal pliers HI-1501 •...
  • Page 13 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 14: 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 a load of (1000±5) g of potable water.
  • Page 15: Diode Removal

    D. DOOR GROSS ASSEMBLY REMOVAL E. HIGH VOLTAGE TRANSFORMER REMOVAL 1) Open the door. 2) Remove the choke cover 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 16 H. AIR DUCT ASSEMBLY REMOVAL J. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable. 1) Disconnect the leadwire from lamp. 2) Remove the turntable shaft VERY CAREFULLY 2) Remove the mounting screw to Latch Board. with a slotted screwdriver. 3) Lay the unit down on its back. I.
  • Page 17 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 completely 2) Remove screws which hold the PCB SUB ASS’Y to microwave activity when the door is opened during the control panel.
  • Page 18: 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 19: 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 20 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 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 Defective Replace 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. oscillation. assembly assembly wire leads from relay 2 and check continuity Continuity.
  • Page 27: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION OVEN CAVITY PARTS INTERIOR PARTS BASE PLATE PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 28: Door Parts

    #EV# DOOR PARTS 13581A 13536A 13552A 13213A 13352A 13720D 14026A 14970A...
  • Page 29: Controller Parts

    #EV# CONTROLLER PARTS 24781M 268711 23572A WTT028 23506A...
  • Page 30: Oven Cavity Parts

    #EV# OVEN CAVITY PARTS 33112U WSZ185 33052A For model WTT010 MAB745W For model WTT020 MAB745B 33390G 35889A 36549S WTP013...
  • Page 31: Latch Board Parts

    #EV# LATCH BOARD PARTS 56912B 43500A 55262A 466001 466003 466001 WSZ085...
  • Page 32 #EV# INTERIOR PARTS (I) Check the rating label of Model and order SVC parts according to the Model No. Model: MAB745W MAB745B * Check the Rating Model No. WSZ002 568771 * Check the Rating Model No. 56411A 56930V * Check the 50FZZA Rating Model No.
  • Page 33 #EV# INTERIOR PARTS (II) Check the rating label of Model and order SVC parts according to the Model No. Model: MAB745W / 01 MAB745B / 01 * Check the Rating Model No. WSZ002 568771 * Check the Rating Model No. 56411A 50FZZA 56930V...
  • Page 34: Base Plate Parts

    #EV# BASE PLATE PARTS 56170D 63302A 63303A WTT021 65006B WSZ002 65006B...

This manual is also suitable for:

Goldstar mab745wGoldstar mab745bMab745wMab745b

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