LG LMVM2277ST Service Manual Download Page 27 | Manualshive

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7-17

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION:

REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

NOTES:

• If the fuse is blown by an improper switch operation, replace all switches and the fuse at the same time.

After replacing the defective switches with new ones, make sure that they are correctly connected.

Fuse blows immediately after
the door is closed.

Fuse blows immediately after
the door is opened.

Fuse blows when the door is closed and START
key is touched.

Improper operation of the primary interlock, secondary
interlock switches and/or the interlock monitor switch.

Malfunction of the high voltage transformer;the high
voltage capacitor including the diode, the magnetron,
the blower motor or the circuit board.

PROBLEMS

CAUSES

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Summary of Contents for LMVM2277ST

Page 1: ...흥 정 판 MICROWAVE OVEN SERVICE MANUAL MODEL LMVM2277ST CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL Website http us lgservice com P NO MFL06272504 June 2007 Printed in Korea ...

Page 2: ...proper alignment integrity and connections d Any defective or misadjusted components in the interlock monitor door seal and microwave generation and transmission systems shall be repaired replaced or adjusted by procedures described in this manual before the oven is released to the owner e A Microwave leakage check to verify compliance with the Federal performance standard should be performed on e...

Page 3: ...TROL PANEL INSTRUCTIONS 4 2 OVERALL CIRCUIT DIAGRAM 5 1 SCHEMATIC DIAGRAM 5 1 GENERAL INFORMATION FOR SERVICE 6 1 GENERAL PRECAUTIONS IN USE 6 1 TRIAL OPERATION 6 1 FEATURES AND SPECIFICATIONS FEATURES 6 1 SERVICE INFORMATION 7 1 PRECAUTIONS AND REPAIR SERVICE TIPS 7 1 MICROWAVE LEAKAGE TEST 7 2 POWER OUTPUT MEASUREMENT 7 3 DISASSEMBLY INSTRUCTIONS 7 4 INTERLOCK CONTINUITY TEST 7 12 TEST AND CHECK...

Page 4: ...h Interlock Monitor Switch Magnetron 2M282H Toshiba Cook top Lamp 12 V 10 W Halogen Cavity Lamp 12 V 20 W Halogen Timer Digital up to 99 min 99 sec in each cooking stage Tray Tempered Safety Glass Overall Dimensions 297 8 W x175 8 H x187 8 D Oven Cavity Size 231 2 W x103 4 H x151 2 D Effective Capacity of Oven Cavity 2 2 Cu ft Accessories Owner s Manual Cooking Guide Installation Manual Exhaust Ad...

Page 5: ...ing operation BEFORE TOUCHING any parts of the oven always remove the power plug from the outlet Remove your watches whenever working close to or replacing the Magnetron DO NOT touch any parts of the control panel circuit A resulting static electric discharge may damage the PCB NEVER operate the oven with no load NEVER injure the door seal and front plate of the oven cavity NEVER put iron tools on...

Page 6: ...GROUNDING INSTRUCTIONS For personal safety this appliance must be fully grounded at all times In the event of an electrical short circuit grounding reduces the risk of electrical shock The plug must be plugged into an outlet that is properly installed and grounded CAUTION This unit is equipped with a 3 prong plug for your safety If the wall outlet is a grounded 3 hole type the unit will be grounde...

Page 7: ...4 1 OPERATING INSTRUCTIONS CONTROL PANEL 2 3 1 4 8 9 5 12 11 6 7 10 13 14 15 17 23 19 20 16 18 22 21 ...

Page 8: ...corn in your microwave oven The oven s sensor will tell the oven how long to cook depending on the amount of humidity it detects from the popcorn 12 COOK Touch this key to cook Baked Potato Vegetable Casserole Rice and Frozen Entree The oven s sensor will tell the oven how long to cook depending on the amount of humidity coming from the food 13 REHEAT Touch this key to reheat Pizza Slice Dinner Pl...

Page 9: ...5 1 OVERALL CIRCUIT DIAGRAM SCHEMATIC DIAGRAM ...

Page 10: ... display window will show the time counting down by seconds D After about 5 minutes make sure the primary interlock switch the secondary interlock switch and the interlock monitor switch operate properly by opening and closing the door several times Touch the START key each time the door is closed E Continue operating the unit Melody sound signal is heard when the time is up The unit will shut off...

Page 11: ...w the limit of 5 mW cm2 All service adjustments should be made for minimum microwave energy leakage readings 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 th...

Page 12: ...servicing The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 1mW cm sq And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NOTE The standard is 5mW cm sq while in the customer s home 1mW cm sq stated here is manufacturer s own voluntary standard for units in customer s home EQUIPMENT TESTER...

Page 13: ...d 3 At least once a year have the electromagnetic energy leakage monitor checked for calibration by its manufacturer 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 vesse...

Page 14: ... A REMOVING POWER AND CONTROL CIRCUIT BOARD Figures 1 2 and 3 1 Remove screws on the base plate Figure 1 2 Remove the screws on the left side of front cavity Figure 1 3 Release latch board from cavity and pull down it Figure 1 4 Release PCB board from cavity and pull down it Figure 2 7 4 DISASSEMBLY INSTRUCTIONS Power Transformer CN1 CN5 CN2 CN4 CN3 CN6 RY2 3Tap Power Relay Screw Control Panel Cir...

Page 15: ...r duct 3 Remove the mounting plate by turning 2 screws securing it to the outer case 4 Remove two screws on the left central edge and two screws on the right central edge of Base plate Remove the Blower plate from the outer case by removing two screws securing it to the outer case 5 Remove four screws on the rear cavity 6 Remove one screw on the right side of outer case 7 Remove the outer case Fig...

Page 16: ...gy leakage is below the limit of 1mW cm2 with a 275 ml water load and 5mW cm2 with a 275 ml water load without the cabinet when measured with a survey meter RD from L V T RD from FAN MOTOR RD from P C B BK from MGT THERMOSTAT BL from P C B PK from P C B RD from P C B WH from L V T WH from P C B Latch Board Interlock Monitor Switch Secondary Interlock Monitor Switch Primary Interlock Monitor Switch...

Page 17: ...djacent 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 cm2 All service adjustments should be made for minimum microwave energy lea...

Page 18: ...ring it to the choke cover 2 Separate the choke cover from the Door by using knifeblade or small screw driver etc 3 Remove two screws securing it to the door handle 4 Remove the door frame 5 Remove two screws securing it to the main PCB 6 Disconnect two flat lead wire and FPC connector Remove the FPC connector from the terminal socket following HOW TO REMOVE THE FPC CONNECTOR on the next page CAUT...

Page 19: ...sert 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 16 NOTE When reconnecting the F P C connector make sure that the holes on the F P C connector are properly engaged with the hooks on the plastic fastener 3 Lock the level of the plastic fastener into t...

Page 20: ...ure 19 b J REMOVING THE TURNTABLE MOTOR 1 Remove the glass tray and plastic tray 2 Remove the base plate by removing 8 screws securing it to the oven cavity Figure 20 3 Disconnect the leadwire from the turntable motor terminals 4 Remove the two screws securing the turntable motor to the oven cavity ASS Y Figure 21 NOTES Remove the leadwire from the turntable motor VERY CAREFULLY Be sure to grasp t...

Page 21: ...7 11 K REPLACING THE HUMIDITY SENSOR 1 Remove the sensor by removing one screw securing it to the air duct See Figure 22 2 Mount the new humidity sensor to the air duct Figure 22 ...

Page 22: ...When the secondary switch operation is abnormal make the necessary adjustment or replace the switch only with the same type of switch C MONITOR SWITCH TEST Disconnect the wire lead from the monitor switch Connect the ohmmeter leads to the common COM and normally closed NC terminals of the switch The meter should indicate closed circuit in the door open condition When the door is closed meter shoul...

Page 23: ...eads 2 Measure resistance ohm meter scale Rx1 Primary winding High Low Secondary winding Filament winding 3 Measure resistance ohm meter scale Rx1000 Primary winding to ground Filament winding to ground 1 Remove wire leads Install the magnetron seal in the correct position Check that the seal is in good condition 2 Measure resistance ohm meter scale Rx1 Filament terminal 3 Measure resistance ohm m...

Page 24: ...E Some inexpensive ohm meters may indicate infinite resistance in both directions 1 Measure continuity ohm meter scale Rx1 2 Remove the lead wires and operate oven at power level 1 through power level 10 RELAY 2 1 Remove wire leads 2 Measure resistance ohm meter scale Rx1 Terminal Red and Yellow Terminal Red and Brown Normal Approximately Terminal 12 to 16 ohms Terminal 9 to 13 ohms Abnormal Infin...

Page 25: ... speed Blue and Grey LOW speed Blue and Brown 1 Remove wire leads 2 Measure resistance ohm meter scale Rx1000 VENTILATION MOTOR Normal Approximately Terminal 18 to 30 ohms Terminal 18 to 30 ohms Abnormal Infinite 1 Remove leads wire 2 Measure resistance ohm meter scale Rx1 Terminal Red and White Terminal Red and Black L V T TURNTABLE MOTOR 1 Disconnect sensor connector from micom computer board 2 ...

Page 26: ...VE ENERGY TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES ...

Page 27: ...ones make sure that they are correctly connected Fuse blows immediately after the door is closed Fuse blows immediately after the door is opened Fuse blows when the door is closed and START key is touched Improper operation of the primary interlock secondary interlock switches and or the interlock monitor switch Malfunction of the high voltage transformer the high voltage capacitor including the d...

Page 28: ...without touching START key when the door is closed GOOD Remove the mate connector of I O CON from the circuit board Does the unit still operate Defective Wire Assembly Replace the circuit board Replace Wire Assembly NO NO YES YES GOOD Measure the voltage at pin NO 1 5 of CN1 Voltage reading 120 V AC Replace the circuit board Defective FAN motor YES NO NO YES Replace FAN motor PROBLEM B Oven lamp t...

Page 29: ...t the high voltage Systems the interlock switches the door sensing and the relay check good 3 The unit with a normal relay continuously operates 4 The buzzer does not sound or continues to sound 5 Some segments of one or more digits do not light up or they continue to light up or segments light when they should not 6 Wrong figures appear 7 The figures of all digits 8 The clock does not keep time p...

Page 30: ...M A PLEASE SET TIME OF DAY does not appear in display window when power supply cord is plugged into wall outlet Check 1 POWER SUPPLY 2 FUSE 3 OVEN CAVITY THERMOSTAT 1 Measure voltage between pin 1 and pin 3 of connector CN1 BL WH Runs Runs 0 120 0 120 120V Replace circuit board Normal circuit board Normal resistance Voltage incorrect Correct connections ...

Page 31: ... seating Normal circuit board Normal contact Poor Normal Secondary switch No continuity Adjust or replace door sensing switch Runs Runs Runs Runs Check operation of fan motor when START ENTER key is touched Measure resistance of H V capacitor see page 7 14 Resistance incorrect Measure resistance of fan motor Terminal A C 12 to 16 ohms Terminal A B 9 to 13 ohms Resistance incorrect Replace fan moto...

Page 32: ...ormal circuit board Contact OK Normal contact Correct seating Check contact of connector Check the contact of relay 8 see page 7 14 Resistance incorrect Check the continuity of H V C see page 7 14 Normal H V T Resistance incorrect Normal H V C Abnormal Replace H V D Normal Magnetron Replace Magnetron Normal Normal H V D Check the continuity of H V D see page 7 14 Replace H V C Normal resistance Re...

Page 33: ...operate when VENT ON OFF key is touched 1 Runs Runs Runs Contact OK NO contact Replace magnetron thermostat and oven thermostat Poor contact Replace circuit board Normal circuit board Contact OK Normal contact Correct seating Check contact of connector see page 7 9 Runs Replace ventilation NO runs Normal ventilation Check the contact of magnetron thermostat and oven thermostat Check 1 POWER SUPPLY...

Page 34: ...ODED VIEW DOOR PARTS 1381 1012 2041 1000 1002 W136 W215 W130 W130 W214 1022 2009 2006 1006 1006 1004 1005 W130 1017 EV CHOKE COVER MUST BE REPLACED WITH A NEW ONE AFTER REMOVING IT FROM THE DOOR DON T RE USE IT ...

Page 35: ...014 2023 2029 3024 3052 5069 3053 3036 3053 3055 3033 6000 5036 3026 3025 3018 3031 3010 3029 W130 W105 W109 W218 W217 W109 W219 W220 W121 W142 W142 W142 W109 W142 3005 6001 3032 3045 W178 W219 3045 W178 W142 W142 3001 W216 EV ...

Page 36: ... 8 3 LATCH BOARD PARTS 4006 4007 4003 4011 4012 4002 4002 4013 4014 4013 4014 4008 4008 W217 W217 EV ...

Page 37: ...00 5071 5012 5003 5063 5018 5002 5000 5067 5009 5008 W109 5028 5051 5023 5707 3002 3384 5409 5024 3901 3009 5206 5062 W119 W105 W101 W101 W101 W144 W144 W144 W144 W144 W144 W144 W144 W101 W101 W144 5063 W104 W101 W144 W221 EV ...

Page 38: ... 8 5 INTERIOR PARTS II 5010 5011 5049 3027 9001 5016 3006 5014 W109 W109 W144 W109 W140 W140 5412 5001 5041 5006 5037 W150 5045 5420 W178 5550 W202 W109 W144 EV ...

Page 39: ... 8 6 INSTALLATION PARTS VINYL BAG 6009 6010 6011 6008 MFL1 OWNERS MANUAL MEZ1 COOKING GUIDE LABEL MFL3 INSTALLATION MANUAL MBM4 UPPER TEMPLATE MBM5 WALL TEMPLATE EV ...

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