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LG LMV1825SB Service Manual

Lg microwave oven service manual
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See also: Owner's Manual & Cooking Guide

MICROWAVE OVEN

SERVICE MANUAL
MODEL: LMV1825SB
LMV1825SW
LMV1825SBQ
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.
website http://www.lgservice.com

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Summary of Contents for LG LMV1825SB

  • Page 1: Microwave Oven

    MICROWAVE OVEN SERVICE MANUAL MODEL: LMV1825SB LMV1825SW LMV1825SBQ CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. website http://www.lgservice.com...

  • Page 2: Safety Precautions

    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

    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. SAFETY PRECAUTIONS ... SPECIFICATIONS... CAUTIONS ... INSTALLATION ... OPERATING INSTRUCTIONS... CONTROL PANEL ...

  • Page 4: Specifications

    Rated Power Consumption...1,500W maximum (Microwave oven+Cook top lamps+Ventilation fan) Microwave Output...1000W (IEC 60705) Frequency ...2,450 MHz Power Supply...120 VAC, 60 Hz Rated Current ...13 Amp. (Microwave oven+Cook top lamps+Ventilation fan) Magnetron Cooling ...Forced Air Cooling Rectification...Rectification Voltage Double Half-Wave Door Sealing ...Choke System Safety Devices...Magnetron Thermal Fuse:...

  • Page 5: Cautions

    Never look into an open waveguide or antenna while the device is energized. • Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity. Never operate the magnetron unless it is properly installed.

  • Page 6: 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 15A or 20A. B. Avoid placing the unit in a location where there is direct heat or splashing water.

  • Page 7: Operating Instructions

    OPERATING INSTRUCTIONS CONTROL PANEL...

  • Page 8: Control Panel Instructions

    18. HOLD WARM: Touch this pad to keep hot, cooked foods warm in your microwave oven for up to 99 minutes 99 seconds. 19. EZ-ON: Touch this pad to set and start quickly at 100% power level.

  • Page 9: Overall Circuit Diagram

    OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM...

  • Page 10: Matrix Circuit For Touch Key Board

    MATRIX CIRCUIT FOR TOUCH KEY BOARD VENT HI/LO/OFF LIGHT CUSTOM HI/LO/OFF LESS CLOCK LIGHT CUSTOM TIMER COOK TURNTABLE STOP CLEAR ON/OFF SENSOR MORE PIZZA TIME COOK AUTO DEFROST KITCHEN Ez-On TIMER POWER LEVEL HOLD START WARM SENSOR SENSOR SENSOR POPCORN VEGETABLE VEGETABLE POTATO...

  • Page 11: General Information For Service

    GENERAL INFORMATION FOR SERVICE GENERAL PRECAUTIONS IN USE A. Never operate the unit when it is empty. Operating the oven with no load may shorten the life of the magnetron. Whenever cooking dry foods (dried fish, bread, etc.) or a small amount of food, be sure to put a glass of water into the cooking compartment.

  • Page 12: Service Information

    SERVICE INFORMATION PRECAUTIONS AND REPAIR SERVICE TIPS PRELIMINARY A. SINCE NEARLY 2,100 VOLTS EXISTS IN SOME CIRCUITS OF THIS UNIT REPAIRS SHOULD BE CARRIED OUT WITH GREAT CARE. The filament leads of magnetron carry High Voltage with respect to ground. Extreme caution must be exercised.

  • Page 13: Microwave Leakage Test

    • Check for microwave leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 4 mW/cm . Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

  • Page 14: Power Output Measurement

    2 mW/cm POWER OUTPUT MEASUREMENT (1) Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of (1000±5) g of potable water. (2) The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 1/8”...

  • Page 15: Disassembly Instructions

    DISASSEMBLY INSTRUCTIONS IMPORTANT NOTES: UNIT MUST BE DISCONNECTED FROM ELEC- TRICAL OUTLET WHEN MAKING REPAIRS, RE- PLACEMENTS, ADJUSTMENTS AND CONTIN- UITY CHECKS. WAIT AT LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED.
  • Page 16 HOW TO REMOVE THE F.P.C. CONNECTOR Follow the steps below as illustrated in Figures 4 and 5 to remove the F.P.C. connector. (1) Hold the edges of the plastic fastener with thumb and forefinger. (Figure 4) (2) Lift up the lever of the plastic fastener from the terminal socket by lightly pressing the lever end with forefinger.
  • Page 17 B. REMOVING THE OUT CASE(Figure 8) (1) Remove the vent grille by removing two screws securing it to the out case. (2) Remove two screws securing it to the air duct. (3) Remove the mounting plate by turning the screws (1 or 2 screws) securing it to the out case.
  • Page 18 C REMOVING THE DOOR INTERLOCK SWITCHES (Figures 9,10) (1) Disconnect the wire leads from the interlock switches. (2) Remove two screws securing the Latch Board. (3) Make necessary replacements and check microwave energy leakage according to “ADJUSTMENT PROCEDURE” on page 7-12. Latch Board Secondary Interlock Switch WH(from H.V.Transformer)
  • Page 19 D. REMOVING MAGNETRON (Figures 11 Through 13) (1) Remove the vent grille by loosening two screws. (Figure 11) (2) Remove the outcase. See page 7-6. (3) Remove three tap tite screws securing the magnetron to the wave guide. (4) Remove the magnetron VERY CAREFULLY. Figure 11 Vent Grille Figure 13...
  • Page 20 E. REMOVING STIRRER FAN (Figures 14 and 15) (1) Remove one rivet ASS'Y securing it to the oven upper plate by using knife blade. (2) Rotate slightly and pull out the stirrer fan cover. (3) Remove the stirrer fan. Figure 15 F.
  • Page 21 (See Figure 19-a) Figure 18 Figure 19-a (3) Carefully pull the ventilation motor ASS'Y out of the microwave oven. (See Figure 19-b) J. REPLACING THE HUMIDITY SENSOR (For sensor model only) (1) Remove the sensor by removing two screws securing it to the air duct.
  • Page 22 K. REMOVING THE TURNTABLE MOTOR (1) Remove the turntable. (2) Remove the turntable shaft VERY CAREFULLY with a slotted screwdriver. (Figure 20) (3) Remove the base plate by removing 7 screws securing it to the oven cavity. (Figure 21) (4) Disconnect the leadwire from the turntable motor terminals.

  • Page 23: Interlock System

    0-1/64" LATCH BOARD CHECK THE DOOR LATCH AND SWITCH CLOSING. NOTE: (1) Set the microwave oven on its side so that you can (2) Close the door tightly and check gaps A and B to Latch Board NOTE: Secondary Interlock Switch...
  • Page 24 TEST THE LATCH AND SWITCH SEQUENCE (5) Open the oven door slowly. Watch the door latch, the Secondary Switch. Release Rod and Lever on the switches to make sure they are zero to the body of the switches in the following sequence: - Primary Interlock Switch - Secondary Interlock Switch - Interlock Monitor Switch...

  • Page 25: Interlock Continuity Test

    INTERLOCK CONTINUITY TEST A. PRIMARY INTERLOCK SWITCH TEST When the door is opened slowly, an audible click should be heard at the same time or successively at intervals and the latches should activate the switches with an audible click. If the latches do not activate the switches when the door is closed, the switches should be adjusted in accordance with the adjustment procedure.

  • Page 26: Test And Checkout Procedures And Trouble Shooting

    TEST AND CHECKOUT PROCEDURES, AND TROUBLE SHOOTING - CAUTIONS - - DISCONNECT THE POWER SUPPLY CORD FROM THE WALL OUTLET WHENEVER REMOVINGING THE CABINET FROM THE UNIT. PROCEED WITH THE TESTS ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.
  • Page 27 COMPONENTS Measure the resistance: (1) Terminal to terminal Ohm- meter HIGH-VOLTAGE CAPACITOR (2) Terminal to case Ohm- meter Measure the continuity: (1) Forward Ohm- meter HIGH-VOLTAGE DIODE (1) Reverse Ohm- meter TEST PROCEDURES Figure 25-a Figure 25-b Figure 26-a Figure 26-b 7-16 RESULTS Normal reading:...

  • Page 28: Test Procedures

    COMPONENTS Measure the resistance between terminal pins of connector KEY CONNECTOR. NOTE: When reconnecting the FPC connector, make sure that the holes on the FPC connector are properly engaged with hooks on the plastic fastener. TOUCH KEY BOARD VENT VENT HI/LO/OFF HI/LO/OFF LIGHT...

  • Page 29: Checkout Procedures

    COMPONENTS Check for continuity of relay 2 with an ohm-meter. (Remove wire leads from relay 2 and operate the unit.) RELAY2 CAUTION : The relay connector 2 must be correctly connected Relay 2. NOTES: • A MICROWAVE ENERGY TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON.
  • Page 30 (2) CHECKOUT PROCEDURES FOR RELAY. - PROBLEM (A) - FAN motor and oven lamp turn on without touching START key when the door is closed. GOOD Replace the circuit board Remove the mate connector of I/O CON from the circuit board. Does the unit still operate? Defective RELAY1...
  • Page 31 (3) CHECKOUT PROCEDURES FOR CIRCUIT BOARD The following symptoms indicate a defective circuit board. 1) The start function fails to operate but the high voltage Systems, the interlock switches, the door sensing and the relay check good. 2) The unit with a normal relay continuously operates. 3) Proper temperature measurement is not obtained.
  • Page 32 7-21...
  • Page 33 7-22...
  • Page 34 7-23...
  • Page 35 7-24...
  • Page 36 7-25...

  • Page 37: Exploded View

    EXPLODED VIEW DOOR 13581A 13536A 13213A 13552A WTP004 14760A 13720D 14890A 14970A 14026A WTT028 13650A...

  • Page 38: Control Panel

    CONTROL PANEL 24781M WTP018 23506A 268711 24810P * 07...

  • Page 39: Oven Cavity

    33530A 34930R 330342 35026G WTT022 535501 35230A OVEN CAVITY WTT027 WTT029 WTT029 WTT027 36912C WTT021 34960A 33550P WTT028 34810Q 33112U WTT022 63303A 368771 56804A 63302A 330341 WTT022...
  • Page 40 LATCH BOARD 43500A 43501A 466001 WSZ084 466003 466001 44510A...
  • Page 41 INTERIOR (I) 33390G 56324A 34370T WSZ002 54810C WTT021 35889A 55238A 50CZZH 56851D 33052A WSZ002 WTP002 56170D WSZ002 55892A 54930F WTT021 56930G 53550F 36549S 568772 WTP013 53300B 340511 WSZ002...
  • Page 42 56912B WTP004 WSZ002 56501A 55231C 33700A INTERIOR (II) 535502 56804A 56901A WTT029 56930V WTT028 WTT028 36549V WTT034 56549F 55262A 56411A 50FZZA WTP013 55900A 56820A 568771...
  • Page 43 INSTALLATION WSZ098 44360A WSZ133 WSZ204 WWZ068 WWZ068 WSZ203 56411A 65862D 63300M 65862B WSZ136 63861A...

  • Page 44: Schematic Diagram Of Pcb

    SCHEMATIC DIAGRAM OF P.C.B 8-14...

  • Page 45: Printed Circuit Board

    PRINTED CIRCUIT BOARD 8-15...
  • Page 46 May, 2003 P/NO : 3828W5S3224 Printed in Korea...

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