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LG LMV1762SB Service Manual
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LG LMV1762SB Service Manual

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MICROWAVE OVEN
SERVICE MANUAL
MODEL: LMV1762SB
CAUTION
BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL06272540
LMV1762SW
LMV1762ST
LMV1763ST
Internal Use Only
March, 2016
Printed in Korea

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  • Page 1 Internal Use Only MICROWAVE OVEN SERVICE MANUAL MODEL: LMV1762SB LMV1762SW LMV1762ST LMV1763ST CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. March, 2016 P/NO : MFL06272540 Printed in Korea...

  • Page 2: Safety Precautions

    CAUTION WARNING TO SERVICE TECHNICIANS PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY a. Do not operate or allow the oven to be operated with the door open. b. Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary;...

  • Page 3: Table Of Contents

    FOREWORD Read this manual carefully. Failure to adhere to or observe the information in this manual may result in exposing yourself to the microwave energy normally contained within the oven cavity. CONTENTS (Page) Safety Precautions .............................. 2 1. Specifications ..............................4 2.

  • Page 4: Specifications

    1. SPECIFICATIONS Rated Power Consumption ........ 1600W maximum (Microwave oven+Cook top lamps+Ventilation fan) Microwave Output..........1000W (IEC60705) Frequency ............2450 MHz ±50 MHz Power Supply ............ 120 VAC, 60 Hz Rated Current ............ 14 Amp. (Microwave oven+Cook top lamps+Ventilation fan) Magnetron Cooling ..........

  • Page 5: Cautions

    2. 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 connected.

  • Page 6: Installation

    3. INSTALLATION BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY. PRECAUTIONS ON INSTALLATION A. Plug the power supply cord into a 120V AC, 60Hz, single-phase power source with a capacity of at least 20 amperes. B. Avoid placing the unit in a location where there is direct heat or splashing water.

  • Page 7: Operation

    4. OPERATION 4-1. Control Panel...

  • Page 8: Explanation Of Control Panel

    4-2. Explanation of Control Panel 1. DISPLAY. The Display includes a clock and 14. Time Defrost. Touch this pad to set a defrost indicators to tell you time of day, cooking time time. settings and cooking functions selected. 15. Auto Defrost. Touch this pad followed by 2.

  • Page 9: Wiring Diagram / Key Matrix

    5. WIRING DIAGRAM / KEY MATRIX 5-1. Wiring Diagram FUSE SMPS C/T Lamp BOTTOM Vent Slow Vent High Vent Low SWITCH SECONDARY Oven Lamp MONITOR SWITCH POWER H.V.TRANSFORMER DIODE H.V.FUSE H.V.CAPACITOR WH PK BR GY...

  • Page 10: Key Matrix

    5-2. Key Matrix KEY MATRIX KEY MATRIX -10-...

  • Page 11: Troubleshooting

    6. TROUBLESHOOTING 6-1. General Information for Service GENERAL PRECAUTIONS IN USE FEATURES AND SPECIFICATIONS FEATURES A. Never operate the unit when it is empty. A. The safety systems incorporated in this model Operating the oven with no load may shorten the are: life of the magnetron.

  • Page 12: Safety Caution

    6-2. Safety Caution A. SINCE NEARLY 4,000 VOLTS EXISTS IN SOME (3) Do not operate the unit until it is completely CIRCUITS OF THIS UNIT REPAIRS SHOULD BE repaired. If any of the following conditions exist, CARRIED OUT WITH GREAT CARE. the unit must not be operated.

  • Page 13: Basic Check Summary

    6-3. Basic Check Summary Symptom: Dead Check: Open/Short FUSE SMPS C/T Lamp BOTTOM Vent Slow Vent High Vent Low SWITCH SECONDARY Oven Lamp MONITOR SWITCH POWER H.V.TRANSFORMER H.V.FUSE DIODE H.V.CAPACITOR Symptom#1(Door is closed): Not Symptom #1(Door is closed): No cooking, Not operating V.M, T.T.M. key, Not started, Operating O.L, V.M, Check: Open/Short when the door T.T.M.

  • Page 14: Troubleshooting

    6-4. Troubleshooting No Display or Dead -14-...
  • Page 15 Is there any beeping sound Replace the Does the display operate? in the continuity test between Fuse. the ends of the fuse? 1 When you push any Key, is Go to No. 6 of this flow chart. there any beeping sound? Power Off 2 Is the connector connected Reconnect or...
  • Page 16 Keypad Failure -16-...
  • Page 17 3 When the door is opened, Do the keys operate? Replace the PCB is the voltage of the door (EBR75341201) sensing part over 4 V? (CN3 Pin1 and Pin2) Power ON 1 Do only the START key and Check PWB EZ-ON keys operate? Go to No.
  • Page 18 No Heat / No Cook FUSE SMPS SWITCH SECONDARY Vent Low BOTTOM Vent High Vent Slow C/T Lamp T/T Motor Oven Lamp MONITOR SWITCH POWER H.V.TRANSFORMER DIODE H.V.FUSE H.V.CAPACITOR -18-...
  • Page 19 3 While the product is After power on, does the Replace the product operate? operating under EZ-ON start, Relay 2 is the voltage of both ends of the D37 over 8 V? 1 Repeat Door Open and close Alternate at least three times. explanation Does product operate? (refer to the...
  • Page 20 Power Off 7 Is the resistance of the high Replace the 5 Is there any beeping sound Adjust the latch High Voltage voltage Transformer out of board Transformer. in the continuity test between range? (Refer to section the ends of the latch board? 9-1,9-2) (Door should be closed) Test Point...
  • Page 21 11 Is the resistance of the high 8 Is the connector connected Reconnect or Replace the repair high voltage to High Voltage capacitor voltage diode out of range? assembly disconnected or the connector. (refer to section 10) Diode. disassembled? Forward Forward Forward Forward...
  • Page 22 3 Push the EZ-ON button Turntable Motor Does Not Work Replace the PCB (operate).Is the voltage of (EBR75341201) both ends of the D37 over 8 Power ON 1 Does the turntable motor Replace the operate? turntable motor. 2 When door is closed, Adjust the Primary latch does the oven lamp turn on?
  • Page 23 4 When the door is opened, Is Turns on automatically Replace the PCB the voltage of the door (EBR75341201) sensing part over 4 V? Does the product turn on (Pin 11 to Pin 12) automatically without pushing the start key? 1 Repeat door open and close Alternate at least three times.

  • Page 24: Microwave Leakage Test

    7. MICROWAVE LEAKAGE TEST CAUTION EQUIPMENT- • Be sure to check microwave leakage prior to • TESTER ((VOLTS-DC, AC, Ohmmeter) servicing the oven if the oven is operating prior to • Microwave survey meter servicing. - Holaday HI-1500 • Service personnel should inform the HI-1501 manufacturer, importer, or assembler of any - Narda...
  • Page 25 MEASUREMENT WITH THE OUTER (1) Do not exceed meter full scale deflection. (2) The test probe must be removed no faster than CASE 1 inch/sec (2.5cm/sec)along the shaded area, REMOVED otherwise a false reading may result. (1) When you replace the magnetron, measure for (3) The test probe must be held with the grip portion microwave energy leakage before the outer case of the handle.

  • Page 26: Power Output Measurement

    8. POWER OUTPUT MEASUREMENT (1) Microwave power output measurement is made 4.187 Mw(T2 –T1)+0.55Mc(T2 –T0) with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting is measured while the microwave generator is with a load of (1000 ± 5) g of potable water. operating at full power.

  • Page 27: Interlock System

    9. INTERLOCK SYSTEM 9-1. Interlock Mechanism The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from microwave leakage. ADJUSTMENT PROCEDURES CHECK THE DOOR LATCH AND SWITCH To avoid possible exposure to microwave energy...
  • Page 28 SPECIFICATIONS TEST THE LATCH AND SWITCH SEQUENCE fuse. (7) When you achieve the proper sequence of (5) Open the oven door slowly. Watch the door latch switches in Steps 5 and 6, tighten the latch board and the Secondary Switch. Release the rod and screws at that point.

  • Page 29: Interlock Continuity Test

    9-2. Interlock Continuity Test A. PRIMARY INTERLOCK SWITCH TEST B. SECONDARY INTERLOCK SWITCH TEST When the door is opened slowly, an audible click Disconnect the wire lead from the secondary should be heard at the same time or successively switch. at intervals and the latches should activate the Connect the ohmmeter leads to the common switches with an audible click.

  • Page 30: Component Testing Information

    10. COMPONENT TESTING INFORMATION CAUTION 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 LEAD WIRES FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER. 2.
  • Page 31 COMPONENTS TEST RESULTS 1. Remove wire leads. CAPACITOR 2. Measure resistance. (ohm meter scale: Rx1000) • Terminal to terminal Normal: Momentarily Infinite and then soon reach 10 mega. ohms • Terminal to case Normal: Infinite. 1. Measure continuity. Forward. Normal:Infinite. DIODE (ohm meter scale: Rx1000) Abnormal: Below 100 ohms...
  • Page 32 N(2) N(1) COMPONENTS TEST RESULTS L(1) 1. Remove wire leads. Normal: TURNTABLE MOTOR 2. Measure resistance. Approximately (ohm meter scale: Rx1000) 2.5 to 3.5 Kohms L(2) Abnormal: Infinite or several. Nmornal: 1. Unplug microwave oven or disconnect power. NOISE FILTER L(1)-L(2)(coil):Less than 2.
  • Page 33 COMPONENTS TEST RESULTS Measure the resistance between terminal TOUCH KEY BOARD When When not pins of connector KEY CONNECTOR. touched touched NOTE: Resistance Less than More than When reconnecting the FPC connector, value make sure that the holes on the FPC 1 megaohm 400 ohms connector are properly engaged with hooks...

  • Page 34: Disassembly Instructions

    11. DISASSEMBLY INSTRUCTIONS Circuit Board IMPORTANT NOTES: (4) Remove 5 screws securing the circuit board. THE UNIT MUST BE DISCONNECTED FROM Circuit Board THE ELECTRICAL OUTLET WHEN MAKING Circuit Board REPAIRS, REPLACEMENTS, ADJUSTMENTS AND CONTINUITY CHECKS. WHEN RECONNECTING THE WIRE LEADS TO ANY PART, MAKE SURE THE WIRING CONNE- CTIONS AND LEAD COLORS ARE CORRECTLY MATCHED ACCORDING TO THE OVERALL CIR-...
  • Page 35 HOW TO REMOVE THE F.P.C. CONNECTOR HOW TO INSERT THE F.P.C. CONNECTOR Follow the steps below as illustrated in Figures 4 Follow the steps below as illustrated in Figures 6 and 5 to remove the F.P.C. connector. and 7 to insert the F.P.C. connector. (1) Insert the F.P.C.
  • Page 36 B. REMOVING THE OUTER CASE(Figure 8) (1) Remove the vent grille by removing the two screws securing it to the outer case. (2) Remove the two screws securing it to the air duct. (3) Remove the mounting plate by loosening the screws (1 or 2 screws) securing it to the outer case.
  • Page 37 C. REMOVING THE DOOR INTERLOCK SWITCHES (Figures 9, 10) (1) Disconnect the wire leads from the interlock switches. (2) Remove the two screws securing the Latch Board. (3) Make any necessary replacements and check for microwave energy leakage according to ADJUSTMENT PROCEDURES on page 7-12.
  • Page 38 D. REMOVING MAGNETRON E. REMOVING STIRRER FAN (Figures 11 Through 12) (Figures 13 and 14) (1) Remove the vent grill by loosening the two (1) Remove one rivet assembly securing it to the screws.(Figure 11) oven upper plate by using a knife blade. (2) Remove the outer case.
  • Page 39 F. REMOVING DOOR (Figure 15) H. ASSEMBLING DOOR (1) Remove the vent grille by loosening the two (1) When mounting the door assembly to the oven screws securing it to the outer case. assembly, be sure to adjust the door assembly (2) Lift up and draw out the door.
  • Page 40 J. REMOVING THE TURNTABLE MOTOR (3) Carefully pull the ventilation motor assembly out ofthe microwave oven. (See Figure 18-b) (1) Remove the glass tray and rotating ring. (2) Remove the turntable shaft VERY CAREFULLY with one hand. (Figure 19) (3) Remove the base plate by removing the 8 screwssecuring it to the oven cavity.

  • Page 41: Exploded View

    #EV# EXPLODED VIEW INTRODUCTION Customer Model Product Code SVC Model Customer Model Product Code SVC Model Customer Model Product Code SVC Model OVEN CAVITY PARTS INTERIOR PARTS DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS...
  • Page 42 #EV# Customer Model Product Code SVC Model DOOR PARTS Customer Model Product Code SVC Model 1005 1002 1004 1000 1381 1006 W262 1007 1009 CONTROLLER PARTS 2004 2381 2008 2006...
  • Page 43 #EV# OVEN CAVITY PARTS 3024 3010 3024 3001 3029 3036 3018 3034 6001 5138 6000 3028 3011 3025 3026...
  • Page 44 #EV# LATCH BOARD PARTS 4000 4002 W102 4001 4003 4004 4002...
  • Page 45 #EV# INTERIOR PARTS(I) W101 3002 5009 5016 5014 5030 3012 5116 3008 5008 5063 3037 3009 5035 W101 5018 5116 W101 5002 5022 5000 5034...
  • Page 46 #EV# INTERIOR PARTS(II) 3028 5045 5038 3027 5006 5010 5037 5001 5041 W101 5024 5058 5043 5044 3004...
  • Page 47 #EV# INSTALLATION PARTS Customer Model Product Code SVC Model 6008 6011 MBM4 6010 6009 VINYL...

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