LG LMC1575BD Service Manual
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LG LMC1575BD Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
MODEL:
LMC1575BD
LMC1575ST
LMC1575SW
LMC1575SB
Any reproduction, duplication, distribution (including by way of email, facsimile or other electronic means), publication, modification, copying or transmission of
this Service Manual is STRICTLY PROHIBITED unless you have obtained the prior written consent of the LG Electronics entity from which you received this
Service Manual. The material covered by this prohibition includes, without limitation, any text, graphics or logos in this Service Manual.
Copyright © 2017 LG Electronics Inc. All rights reserved. Only training and service purposes
P/NO.: MFL69902602
February, 2017
Printed in Korea

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  • Page 1 Any reproduction, duplication, distribution (including by way of email, facsimile or other electronic means), publication, modification, copying or transmission of this Service Manual is STRICTLY PROHIBITED unless you have obtained the prior written consent of the LG Electronics entity from which you received this Service 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 INSTALLATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-1...

  • Page 4: Specifications

    SPECIFICATIONS ITEM DESCRIPTION Power Requirement Power Input Voltage 120 V~ 60 Hz Single phase, 3 wire grounded Power Consumption 1250 watt Initial Power Requirement 1920 watt Power Output 1200 watt Max. microwave power (IEC60705) Microwave Frequency 2450 MHz Magnetron 2M286.A21TBG Timer Digital, Up to 99min 59sec.

  • Page 5: Cautions

    CAUTIONS MICROWAVE RADIATION Unlike other appliances, the microwave oven is high-voltage and high-current equipment. Personnel should not be exposed to the microwave energy which may Though it is free from danger in ordinary use, extreme care should be radiate from the magnetron or other microwave generating device if it is taken during repair.
  • Page 6 H.V Transformer L - N(Input) Voltage Downloader Diode Connector High Voltage MGT(Output) Communication Comm. Diode Connector Connector MGT(Output) Sub PCB H.V Capacitor High Voltage Capacitor LMC1575BD /00 LMC1575BD /01 LMC1575ST /00 LMC1575ST /01 LMC1575SW /00 LMC1575SW /01 LMC1575SB /00 LMC1575SB /01...

  • Page 7: Installation

    INSTALLATION BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. INSTALLING GROUNDING INSTRUCTIONS 1. Empty the microwave oven and clean inside it with a soft, damp cloth. Check for For personal safety,this appliance must be fully grounded at all times. damage such as misaligned door, damage around the door or dents inside the In the event of an electrical short circuit, grounding reduces the risk of electrical cavity or on the exterior.

  • Page 8: Operating Instructions

    OPERATING INSTRUCTIONS FEATURES...

  • Page 9: Control Panel

    CONTROL PANEL 1. SMART DIAGNOSIS: Hold the mouthpiece of a phone up to this icon when directed to by service center personnel, to help diagnose problems with the oven when calling for service. 2. DISPLAY: The Display includes a clock and indicators to tell you time of day, cooking time settings, and cooking functions selected.

  • Page 10: Operating Sequence

    OPERATING SEQUENCE 4. Variable power cooking control The following is a description of component functions during oven operation. High Voltage Inverter Power Supply controls output power by the signal from 1. Inverter power supply circuit. Digital Programmer Circuit. Power relay always stay on, but PWM (Pulse Width The inverter power supply circuit powered from the line voltage, 120 V~ 60 Hz Modulation) signal controls microwave output power AC input supplies 4000 V DC to the magnetron.

  • Page 11: Schematic Diagram

    SCHEMATIC DIAGRAM...

  • Page 12: Circuit Description

    CIRCUIT DESCRIPTION GENERAL DETAILS WHEN THE OVEN IS SET AT POWER LEVEL • The SMPS supplies the necessary voltage to the micom controller when power • The inverter control micro wave out-put power from 100 % to 30 % by controlling cord is plugged in.

  • Page 13: 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 14 MEASUREMENT WITH OUTER CASE REMOVED NOTES WHEN MEASURING • When you replace the magnetron, measure for microwave energy leakage • Do not exceed meter full scale deflection. before the outer case is installed and after all necessary components are • The test probe must be moved no faster than replaced or adjusted.

  • Page 15: Measurement Of Microwave Power Output

    MEASUREMENT OF MICROWAVE POWER OUTPUT The formula to calculate energy efficient is IEC method. MW power output (unit: W) • Necessary equipment P = {4.187 x m x (T ) + 0.55 x m x (T )} / t 1. Thermo-hygrometer (T Energy efficiency 2.

  • Page 16: Disassembly And Adjustment

    DISASSEMBLY AND ADJUSTMENT A. OUTER CASE REMOVAL D. PCB ASSEMBLY REMOVAL 1) Disconnect the power supply cord from the outlet. 1) Remove the control panel assembly from the cavity. (Refer to control panel 2) Remove the screws from the rear and both side of the case. assembly removal on previous step.) The outer case must be moved backward to be lifted off.
  • Page 17 E. DOOR ASSEMBLY / REMOVAL Remove door assembly 1) Open the door. 2) Check door harness connector (1) disconnected that connector locate on Upper cavity. 3) Remove screw on harness cover and remove Harness cover after remove screw with screwdriver.(2) on base plate around lower hinge. 4) Push locker under upper hinge to left using screwdriver.
  • Page 18 F. AIR DUCT ASSEMBLY / REMOVAL H. REMOVING THE TURNTABLE MOTOR 1) Remove the mounting screw to the magnetron. 1) Remove the turntable, rotating ring and shaft. 2) Lay the unit down on its back. G. MAGNETRON REMOVAL 3) Remove the turntable motor cover. The turntable base cover is easily removed by pinching the eight parts with 1) Disconnect the lead wire from the magnetron.
  • Page 19 I. INVERTER REMOVAL K. INTERLOCK SYSTEM 1) Disconnect the lead wire from magnetron, Harness, Controller PCB 1) INTERLOCK MECHANISM 2) Remove the ground screw. The door lock mechanism is a device which has 3) Remove the 4 screws holding the inverter on baseplate. been specially designed to eliminate microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the J.
  • Page 20 1) Remove the upper inverter supporter both side using Flat blade screwdriver. 2) Remove the screw and washer using Phillips screwdriver 3) Push the inverter backward and remove the inverter. LMC1575BD /00 LMC1575ST /00 LMC1575SW /00 LMC1575SB /00 LMC1575BD /01...

  • Page 21: 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 FOR PRIMARY SWITCH / TYPE NO.SZM-V 16-FA-61 FOR MONITOR SWITCH / TYPE NO.SZM-V 16-FA-63 FOR SECONDARY SWITCH A. PRIMARY INTERLOCK SWITCH TEST Connect the ohmmeter leads to the common (COM) and normally open (NO) terminals of the switch.

  • Page 22: Component Test Procedure

    Inverter PCB Bridge diode IGBT Bridge diode IGBT (Wire leads removed) High Voltage Diode LMC1575BD /00 LMC1575BD /01 LMC1575ST /00 LMC1575ST /01 LMC1575SW /00 LMC1575SW /01 LMC1575SB /00 LMC1575SB /01 1. Bridge Diode (check diode test mode) AC 1 → + AC 2 →...
  • Page 23 COMPONENTS TEST PROCEDURE RESULTS MAGNETRON Antenna (Wire leads removed) 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. RELAY Unit working : 0Ω Check for continuity of relay 2 with an ohm-meter.
  • Page 24 COMPONENTS TEST PROCEDURE RESULTS Humidity Sensor Check sensor wire open using tester If sensor open, exchange sensor. NOTE : • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON. • MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION. •...

  • Page 25: 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 26 (TROUB LE 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. 3. A distinct change in the brightness of one or more numbers in display. 4.
  • Page 27 (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 of 1. Fuse blows. Continuity. Replace fuse, monitor switch. monitor switch (with Latch board assembly door closed).
  • Page 28 NOTE : Do not separate micro switches from latch board. this may damage to latch board. If micro switch is fault, replace latch board assembly. Check continuity of 2. Fuse does not blow. No continuity. Defective thermostat. Replace thermostat. thermostat. Continuity.
  • Page 29 (TROUBLE 4) Oven seems to be operating but little heat is produced in oven load. CONDITION CHECK RESULT CAUSE REMEDY Check the power source Lower than 90% of rating Decrease in power source Suggest customer contact Output is low. voltage. voltage.
  • Page 30 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY Check wiring on Defective wiring on Connect wire on No microwave oscillation. Abnormal Magnetron. Magnetron Magnetron Normal. Check inverter PCB Abnormal Defective Replace...

  • Page 31: Trouble Shooting For Inverter Pcb

    Trouble shooting for inverter PCB Inverter PCB (Inverter PCBA : EBR817180XX) <Inverter PCB ‘TOP’ view> <Inverter PCB ‘BOTTOM’ view> LMC1575BD /00 LMC1575BD /00 LMC1575ST /00 LMC1575ST /00 LMC1575SW /00 LMC1575SW /00 LMC1575SB /00 LMC1575SB /00 Heat sink Capacitor Bridge IGBT...
  • Page 32 Inverter Supporter check. (LMC1575BD /00 LMC1575ST /00 LMC1575SW /00 LMC1575SB /00) • Check 4 points of the hook (both sides) - Inverter supporter hold inverter PCB and guide air flow - If the supporter is not assembled correctly air flow is not good on inverter PCB.
  • Page 33 Inverter Supporter check. (LMC1575BD /01 LMC1575ST /01 LMC1575SW /01 LMC1575SB /01) • Check 4 points of the hook (both sides) - The supports fix inverter PCB and make air-flow. - If the supports is not correctly assembled, air-flow is not good on the inverter PCB.
  • Page 34 Error Code Case ※ F-13, 14, 15, 16, 19 : These don’t appear on the display. When error display mode is selected, It is displayed on the display. Error cord Symptom REMEDY 1. Remove any water or dirt from the touch buttons. Key Error 2.
  • Page 35 Symptom : Dead, Not heating LMC1575BD /00 LMC1575ST /00 LMC1575SW /00 LMC1575SB /00 Symptom : Not heating (F-13, F-14, F-15, F19) Symptom : Check : Open / Short (D5) Not heating (F-13, F-14, F-15, F-19) Symptom : Symptom : Check : Open / Short (D8, D9))
  • Page 36 Symptom : Dead, Not heating LMC1575BD /01 LMC1575ST /01 LMC1575SW /01 LMC1575SB /01 Symptom : Symptom : Symptom : Not heating (F-13, F-14, F-15, F19) Not heating (F-13, F-14, F-15, F-19) Dead Check : Open / Short (D5) Check : Open / Short (D8, D9)
  • Page 37 Inverter wiring check. ① High voltage wire : IInverter supply high voltage and current to Magnetron though this wire ② Inverter earth wire : If earth is loose or not fixed, inverter work not correctly and make current leakage. Make sure earth wire fix correctly after change inverter PCB.
  • Page 38 1. F-11 Inverter / SMPS PCB Check LMC1575BD /00 LMC1575ST /00 • Check Connector pin (CN3, CN8) LMC1575SW /00 LMC1575SB /00 Inverter : CN3 6-7 pin ※ Tester mode : Beep mode Status Test result normal Open (OL) Abnormal Short (Beep)
  • Page 39 2. F-16 or F-17 Inverter PCB Check LMC1575BD /00 LMC1575ST /00 LMC1575SW /00 • Check TH91 (Thermistor) LMC1575SB /00 ※ Tester mode : Beep or resistance mode Status Test result Normal 20Kohm↓ @ Room temperature Abnormal Open or Short Example : abnormal 17.42Kohm @ Room temperature...
  • Page 40 4. F-19 Inverter PCB Check LMC1575BD /00 LMC1575ST /00 LMC1575SW /00 LMC1575SB /00 ※ Tester mode : Beep mode • Check D5 (Bridge Diode), D8 / D9 (High Voltage Diode) Status Test result Normal Open (OL) Abnormal Short (Beep) Bridge Diode : AC Checking...
  • Page 41 Symptom : Not heating (F-11, F-13, F-14, F-15, F-19) LMC1575BD /00 Not heating (Cool : on display) LMC1575ST /00 LMC1575SW /00 • Check inverter PCB _ IC parts LMC1575SB /00 Check temperature on display, after 3 minutes check it again.
  • Page 42 1. F-11 Inverter / SMPS PCB Check LMC1575BD /01 LMC1575ST /01 LMC1575SW /01 • Check Connector pin (CN3, CN8) LMC1575SB /01 Inverter : CN3 6-7 pin ※ Tester mode : Beep mode Status Test result Normal Open (OL) Abnormal Short (Beep)
  • Page 43 2. F-16 or F-17 Inverter PCB Check LMC1575BD /01 LMC1575ST /01 LMC1575SW /01 • Check TH91 (Thermistor) LMC1575SB /01 ※ Tester mode : Beep or resistance mode Status Test result Normal 20Kohm↓ @ Room temperature Abnormal Open or Short Example : abnormal 17.96 Kohm @ Room temperature...
  • Page 44 4. F-19 Inverter PCB Check LMC1575BD /01 LMC1575ST /01 LMC1575SW /01 LMC1575SB /01 ※ Tester mode : Beep mode • Check D5 (Bridge Diode), D8 / D9 (High Voltage Diode) Status Test result Normal Open (OL) Abnormal Short (Beep) + ~ ~ -...
  • Page 45 Symptom : Not heating (F-11, F-13, F-14, F-15, F-19) LMC1575BD /01 Not heating (Cool : on display) LMC1575ST /01 LMC1575SW /01 • Check inverter PCB _ IC parts LMC1575SB /01 Check temperature on display, after 3 minutes check it again.
  • Page 46 Inverter supporter upper type Inverter supporter lower type 5-34...
  • Page 47 LMC1375** LMC0975** LMC2075** LMC1575** inverter supporter upper inverter supporter lower Pro inverter supporter upper Pro inverter supporter lower inverter & Pro inverterMGT harness ferrite core 5-35...

  • Page 48: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION MODEL: Old (Inverter) New (Pro Inverter) Customer Model Product Code SVC Model Customer Model Product Code SVC Model...
  • Page 49 #EV# DOOR PARTS 1005 1002 1004 1000 1384 1006 1114 1007...
  • Page 50 #EV# CONTROL PANEL PARTS 2002 2004 2001 2006 2000...
  • Page 51 #EV# OVEN CAVITY PARTS 3161 3001 W607 3002 3012 3034 3009 3008...
  • Page 52 #EV# LARCH BOARD PARTS 4001 W509 NSP : No Service Parts...
  • Page 53 #EV# INTERIOR PARTS 5011 W101 5004 5016 5014 W140 5010 W520 5001 5041 5012 5007 5003 5006 5009 W101...
  • Page 54 #EV# BASE PLATE PARTS 5474 5471 5472 6100 507V W701 5473 6001 6011 6007 W520...

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