website http://www.lgservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: LMV1825SB LMV1825SW LMV1825SBQ CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CAUTION 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.
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. TABLE OF CONTENTS (Page) SAFETY PRECAUTIONS ......................................................................................................... Inside front page SPECIFICATIONS................................................................................................................................
SPECIFICATIONS Rated Power Consumption..................................................1,500W maximum (Microwave oven+Cook top lamps+Ventilation fan) Microwave Output.................................................................1000W (IEC 60705) Adjustable 100W through 1000W, 10 steps Frequency .............................................................................2,450 MHz 50 MHz Power Supply........................................................................120 VAC, 60 Hz Rated Current .....
CAUTIONS Unlike other appliances, the microwave oven is high-voltage and high-current equipment. Though it is free from danger in ordinary use, extreme care should be taken during repair. MICROWAVE RADIATION Personnel should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating device if it is improperly used or connection. All input and output microwave connections, waveguide, flange, and gasket must be secure.
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. C. Install the unit on the mounting plate firmly. D. Place the unit as far away as possible from TV, radio, etc. to prevent interference.
OPERATING INSTRUCTIONS CONTROL PANEL 1 4 2 3 5 7 6 9 8 10 11 12 13 14 16 15 19 17 18 22 20 21 25 23 24 4-1
CONTROL PANEL INSTRUCTIONS 14. STOP/CLEAR: Touch this pad to stop the oven or to clear all entries. 1. DISPLAY: The Display includes a clock and indicators to tell you time of day, cooking time settings and cooking functions selected. 15. CLOCK: Touch this pad to enter the time of day. 2. MORE: Touch this pad to add ten seconds of cooking time each time you press it. 16. START: Touch this pad to start a function. If you open the door after oven begins to cook, START again. 3.
OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM 5-1
MATRIX CIRCUIT FOR TOUCH KEY BOARD 2 1 VENT HI/LO/OFF N.C 3 5 4 7 6 N.C N.C TIME COOK 5 0 8 LIGHT HI/LO/OFF CUSTOM SET N.C N.C AUTO DEFROST 6 1 LESS CLOCK Ez-On N.C KITCHEN TIMER 7 2 CUSTOM COOK LIGHT TIMER N.C N.C POWER LEVEL 8 3 TURNTABLE ON/OFF STOP CLEAR START N.
GENERAL INFORMATION FOR SERVICE FEATURES AND SPECIFICATIONS FEATURES 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. The glass turntable may become hot after operating, be careful when touching it. B.
SERVICE INFORMATION PRECAUTIONS AND REPAIR SERVICE TIPS PRELIMINARY (3) Do not operate the unit until it is completely repaired, if any of the following conditions exist. The unit must not be operated. (a) The door does not close firmly. (b) The hinge is broken. (c) The door seal is damaged. (d) The door is bent or warped, or there is any other visible damage on the unit that may cause microwave energy leakage. NOTE: Always keep the seal clean.
MICROWAVE LEAKAGE TEST MEASURING MICROWAVE ENERGY LEAKAGE CAUTIONS • Be sure to check microwave leakage prior to servicing the oven if the oven is operative prior to servicing. • The service personnel should inform the manufacture importer, or assembler of any certified oven unit found to have a microwave emission level in excess of 5 mW/cm2 and should repair any unit found to have excessive emission levels, at no cost to the owner, and should ascertain the cause of the excessive leakage.
MEASUREMENT WITH THE OUTER CASE REMOVED NOTE WHEN MEASURING (1) Do not exceed meter full scale deflection. (2) The test probe must be moved no faster than 1 inch/sec (2.5cm/sec) along the shaded area, otherwise a false reading may result. (3) The test probe must be held by the grip portion of the handle. A false reading may result if the operator’s hand is between the handle and the probe. (4) When testing near a corner of the door, keep the probe perpendicular to the surface being tested.
DISASSEMBLY INSTRUCTIONS (4) Remove 3 screws securing the circuit board. IMPORTANT NOTES: UNIT MUST BE DISCONNECTED FROM ELECTRICAL OUTLET WHEN MAKING REPAIRS, REPLACEMENTS, ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY HAS FULLY DISCHARGED. THE CAPACITOR SHOULD BE DISCHARGED BY USING INSULATED WIRE - I.E. TEST PROBE CONNECTED TO 10K-OHM RESISTOR IN SERIES TO GROUND.
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 and 5 to remove the F.P.C. connector. Follow the steps below as illustrated in Figures 6 and 7 to insert the F.P.C. connector. (1) Insert the F.P.C. connector into the terminal socket securely with the fingers. (2) Hold the plastic fastener with thumb and forefinger of the other hand, and push it slowly into the terminal socket. (Figure 6) NOTE: When reconnecting the F.P.
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. (4) Remove two screws on the left central edge and one screws on the right central edge of Base plate. Remove the Mount, All from the out case by removing one screw securing it to the out case.
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 Latch Board Secondary Interlock Switch WH(from H.V.
NOTES: • When removing the magnetron, make sure that its dome does not hit any adjacent parts, or it may be damaged. • When replacing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. • After replacing the magnetron, check for microwave energy leakage with a survey meter Check microwave energy leakage must be below the limit of 5 mW/cm 2 . (All service adjustments should be made for minimum microwave energy leakage readings.) D.
E. REMOVING STIRRER FAN F. REMOVING DOOR (Figure 16) (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. (1) Remove the vent grille by two screws securing it to the outcase loosening. (2) Lift up and draw the door.
(3) Carefully pull the ventilation motor ASS'Y out of the microwave oven. (See Figure 19-b) H. ASSEMBLING DOOR (1) When mounting the door assembly to the oven assembly, be sure to adjust the door assembly parallel to the chassis. Also adjust so the door has no play between the inner door surface and oven frame assembly. If the door assembly is not mounted properly, microwaves may leak from the clearance between the door and the oven. Space Figure 19-b I. REMOVING THE VENTILATION MOTOR J.
NOTES: • Remove the leadwire from the turntable motor VERY CAREFULLY. • Be sure to grasp the connector not the wires when removing. 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. (5) Remove the 2 screws securing the turntable motor to the oven cavity ASS'Y.
INTERLOCK SYSTEM 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 the microwave leakage. ADJUSTMENT PROCEDURES To avoid possible exposure to microwave energy leakage, adjust the door latches and interlock switches, using the following procedure. CHECK THE DOOR LATCH AND SWITCH CLOSING. NOTE: The outer cover of the microwave oven is removed.
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: (7) When you achieve the proper sequence of switches in Steps 5 and 6, tighten the latch board screws at that point.
INTERLOCK CONTINUITY TEST A. PRIMARY INTERLOCK SWITCH TEST B. SECONDARY INTERLOCK SWITCH TEST Disconnect the wire lead from the secondary switch. Connect the ohmmeter leads to the common (COM) and normally open (NO) terminals of the switch. The meter should indicate an open circuit in the door open condition. When the door is closed, the meter should indicate a closed circuit.
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. (SEE FIGURE 24) Secondary Winding Filament Winding - ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF WATER IN CONTAINER) IN THE OVEN.
COMPONENTS TEST PROCEDURES Measure the resistance: (1) Terminal to terminal Normal reading: Momentarily indicates several ohms, and then gradually returns to infinite ohms. Abnormal reading: Indicates continuity or infinite ohms from the beginning. Ohmmeter HIGH-VOLTAGE CAPACITOR RESULTS Figure 25-a Normal readings: Infinite. (2) Terminal to case Abnormal reading: Indicates continuity. Ohmmeter Figure 25-b Normal readings: continuity.
COMPONENTS TEST PROCEDURES RESULTS 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. MATRIX CIRCUIT FOR TOUCH KEY BOARD Resistance value When touched When not touched Less than More than 400 ohms 1 mega ohm FPC CONNECTOR Top 1 2 3 4 5 6 7 8 9 10 11 12 13 CONNECTOR(KEY CON) TOUCH KEY BOARD 2 1 VENT HI/LO/OFF N.C 3 5 4 N.C N.
COMPONENTS TEST PROCEDURES Check for continuity of relay 2 with an ohm-meter. (Remove wire leads from relay 2 and operate the unit.) Relay 2 RELAY2 Figure 32 RESULTS POWER LEVEL 1 4 sec 18 sec 2 6 sec 16 sec 3 8 sec 14 sec 4 10 sec 12 sec 5 12 sec 10 sec 6 14 sec 8 sec 7 16 sec 6 sec 8 18 sec 4 sec 9 20 sec 2 sec 10 22 sec 0 CAUTION : The relay connector 2 must be correctly connected Relay 2.
(2) CHECKOUT PROCEDURES FOR RELAY. - PROBLEM (A) FAN motor and oven lamp turn on without touching START key when the door is closed. NO GOOD YES Remove the mate connector of I/O CON from the circuit board. Does the unit still operate? NO Replace the circuit board YES Defective RELAY1 Replace RELAY1 - PROBLEM (B) FAN motor and oven lamp turn on When the door is closed and START key is touched. NO YES GOOD Measure the voltage at pin NO.
(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. 4) The buzzer does not sound or continues to sound.
7-21 Measure voltage between pin 1 and pin 3 of connector CN1. WH RD 1 Measure resistance of touch key board after removing connector S1. (See page 7-4 and 7-17) 120 120 Resistance incorrect Normal resistance Voltage incorrect 0 120V 0 Replace touch key board. Check contact of connector S1 Correct connections Replace circuit board Check: 1. POWER SUPPLY 2. FUSE (See CHECKOUT PROCEDURES FOR FUSE BLOWING: on page 7-18) 3.
7-22 Check continuity of connector CN2 between Pin 1(PK) and pin 3(BL) when the door is closed No continuity Continuity OK Check: 1. TOUCH KEY BOARD (START KEY FUNCTION) 1 Check operation of fan motor when START key is touched. Check: 1. AIR VENTS No operation Normal operation PROBLEM - D: Unit operation seems to be normal but little or no heating is produced in oven load. 1 PROBLEM - C: Display does not start countdown when START key is touched.
7-23 2 1 Measure resistance of H.V.Transformer (see page 7-15) Check the contact of relay 2(see page 7-18) Normal resistance Resistance incorrect Contact OK NO continuity Replace circuit board Replace H.V.T. Normal circuit board Check the continuity of H.V.C. (see page 7-16) Normal H.V.T. Check contact of connector S1 Check: 1. PRIMARY AND SECONDARY INTERLOCK SWITCHES 2.
7-24 1 Check normal operation circuit board PROBLEM - F: No buzzing when touching the key, between stages or at end of cooking Replace circuit board Normal circuit board Runs
7-25 Check: 1. POWER SUPPLY 2. FUSE Check the contact of magnetron thermal fuse and oven thermostat 1 Contact OK NO contact Check contact of connector S1 (see page 7-4) Replace magnetron thermal fuse and oven thermostat Contact OK Poor contact PROBLEM - G: Ventilation fan does not operate when FAN HIGH/LOW key is touched.
EXPLODED VIEW DOOR 13581A 13536A 13213A WTP004 13552A 14760A 13720D 14890A 14970A 14026A WTT028 13650A 8-1
CONTROL PANEL 24781M WTP018 23506A 268711 24810P * 07 8-2
OVEN CAVITY WTT021 34960A WTT027 WTT029 33550P WTT028 WTT029 33530A WTT027 34810Q 33112U WTT022 63303A 368771 34930R 330342 56804A 35026G WTT022 535501 63302A 36912C 330341 35230A WTT022 8-3
LATCH BOARD 43500A 43501A 466001 WSZ084 466003 466001 44510A 8-4
INTERIOR (I) 33390G 56324A 34370T WSZ002 WTT021 35889A 54810C 55238A 50CZZH 56851D 33052A WSZ002 WTP002 56170D WSZ002 55892A 54930F WTT021 56930G 53550F 36549S WTP013 568772 53300B 340511 WSZ002 8-5
INTERIOR (II) 36549V 535502 WTT034 56912B 56549F 56804A 56901A WTP004 55262A WTT029 WSZ002 56411A 56501A 56930V 50FZZA 55900A WTT028 56820A 55231C 568771 *01 WTT028 *02 *04 33700A 8-6 WTP013
INSTALLATION WSZ098 44360A WSZ133 WSZ204 WWZ068 WWZ068 WSZ203 56411A 65862D 63300M 65862B WSZ136 63861A 8-7
SCHEMATIC DIAGRAM OF P.C.B 8 9 10 11 12 13 VENT HI/LO/OFF 1 N.C 2 N.C 3 N.C 4 TIME COOK 5 6 0 2 1 5 7 AUTO DEFROST 6 N.C N.C 3 N.C 8 4 Ez-On POWER LEVEL 9 CUSTOM SET N.C HOLD WARM CLOCK N.C N.
PRINTED CIRCUIT BOARD 8-15
P/NO : 3828W5S3224 May, 2003 Printed in Korea
