LG LRMM1430SB Service Manual Download Page 30

Page: 30 / 48

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CONDITION

CHECK

RESULT

CAUSE

REMEDY

1. Setting time

does not count
down when
touching START
pad.

2. Fan motor or

oven lamp do
not turn on.

No continuity.

Continuity.

Continuity

Defective Power
PCB assembly.

Loose connection.

Replace Power
PCB assembly.

Connect them
tightly.

No continuity

Abnormal

Check fan motor.

Defective fan motor.

Replace fan motor.

Abnormal

Normal

Check oven lamp.

Defective oven lamp.

Replace oven lamp.

Defective
secondary switch.

Replace
secondary switch.

Check continuity
of secondary
switch (with
door closed).

Check the con-
nection between
CN1 connector
and PCB
assembly.

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired

program times are set and START pad is touched.

(TROUBLE 4) Oven seems to be operating but little heat is produced in oven load.

NOTE : Simple test of power output-conducted by heating one liter water for one min. if available.

Minimum 8.5°C temperature rise is normal condition.

CONDITION

CHECK

RESULT

CAUSE

REMEDY

Output is low

Lower than 90% of
rating voltage.

Normal

Defective
Magnetron.

Replace
Magnetron.

Decrease in power
source voltage
with load.

Suggest customer
contact local
electric power
utility co. or
qualified
electrician.

Check the
power source
voltage.

Summary of Contents for LRMM1430SB

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL LRMM1430SW LRMM1430SB CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL website http www lgservice com ...

Page 2: ...for 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 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 each oven...

Page 3: ... 5 4 Trial Operation 5 5 Features and Specifications 5 6 6 Overall Circuit Diagram 7 8 7 Operating Procedures 9 11 8 Procedure for Measuring Microwave Energy Leakage 12 13 9 Disassembly Instructions 14 18 10 Interlock Continuity Test 19 11 Test and Checkout Procedures and Troubleshooting A Test Procedures 20 22 B Checkout Procedures 23 25 C Troubleshooting 26 30 12 Exploded View 31 37 13 Replaceme...

Page 4: ... Go to step 3 and follow all steps in order ADJUST THE LATCH AND SWITCH CLOSINGS 3 Loosen the screw holding the plastic latch board as shown 4 With the oven door closed tightly move the latch board upward toward the top of the oven and or away from the door latch until the gaps are less than 1 64 0 5 mm Hold the latch board tightly in this position until you check the sequence of the switches in s...

Page 5: ... 4 LATCH BOARD PRIMARY INTERLOCK SWITCH LATCH LATCH BOARD A B 0 1 64 0 1 64 DOOR LATCH SECONDARY INTERLOCK SWITCH MONITOR INTERLOCK SWITCH Figure 1 a Figure 1 b ...

Page 6: ...ey Make sure the cavity light comes on The unit will begin cooking and the display window will show the time counting down by seconds E After about 5 minutes make sure the primary interlock switch the secondary interlock switch and the interlock monitor and oven lamp switch operate properly by opening and closing the door several times Touch the START key each time the door is closed F Continue op...

Page 7: ...5 C Fuse 20A Primary Interlock Switch Secondary Interlock Switch Interlock Monitor Magnetron 2M261 Cavity Lamp 125V 20W Timer Digital up to 99 mm 99 sec in each cooking stage Tray Tempered Safety Glass Overall Dimensions 203 4 W x 151 4 D x 191 4 H Oven Cavity Size 171 4 W x 9 D x 163 4 H Effective Capacity of Oven Cavity 1 4 Cu ft Accessories Owner s Manual Cooking Guide Turntable Rotating Ring A...

Page 8: ...6 OVERALL CIRCUIT DIAGRAM A SCHEMATIC DIAGRAM 7 Figure 3 ...

Page 9: ...B MATRIX CIRCUIT FOR TOUCH KEY BOARD 8 Figure 4 ...

Page 10: ...set cooking time and power level 8 Melt Touch this pad to melt chocolate cheese butter or marshmallows 9 Auto Defrost This pad is an accurate defrosting method for meat poultry fish and bread 10 Q Defrost Touch this pad to defrost foods quickly 11 More Less Touch these pads to adjust cooking time in 10 second increments 12 Cook time Touch this pad to set a cooking time 13 Power Touch this pad to s...

Page 11: ... categories of preset cooking time and power level Oatmeal Bacon Scrambled Eggs 7 CLOCK Key Used in setting Time of Day 8 COOK TIME Key The TIME key is used to set the cooking time Touch the TIME key and then the number keys that correspond to the desired cooking time The remaining time is continuously displayed during cooking 9 STOP CLEAR Key Used to stop the oven or clear all entries except CLOC...

Page 12: ... 5 SOFTEN 1 Touch STOP CLEAR 2 Touch SOFTEN Four different soften menus are provided 3 Select Menu 1 to 4 See cooking guide 4 Enter the amount of the Category 6 MELT 1 Touch STOP CLEAR 2 Touch MELT Four different melt menus are provided 3 Select Menu 1 to 4 See cooking guide 4 Enter the amount of the Category 7 AUTO DEFROST 1 Touch STOP CLEAR 2 Touch AUTO DEFROST Three different defrosting categor...

Page 13: ...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 Electromagnetic energy leakage monitor NARDA 8100B HOLADAY HI 1501 600cc glass beaker Glass thermometer 1000C B MEASURING MI...

Page 14: ...sured values for future reference Also enter the information on the service invoice 2 Should the microwave energy leakage not be more than 1mW cm sq after determining that all parts are in good condition functioning properly and genuine replacement parts which are listed in this manual have been used 3 At least once a year have the electromagnetic energy leakage monitor checked for calibration by ...

Page 15: ...VERALL CIRCUIT DIAGRAM ESPECIALLY SWITCHES AND HIGH VOLTAGE CIRCUIT A REMOVING OUT CASE Figure 8 1 Unfasten five screws from the rear section 2 Unfasten two screws from the side section 3 Push the out case back about 1 inch 3cm 4 Lift the case from the set B DOOR ASSEMBLY REMOVAL Figure 9 1 Remove out case 2 Unfasten two screws for removing deco front 3 Disconnect the lead wires from main board an...

Page 16: ...D SEPARATE CAVITY AND BASE PLATE Figure 11 1 Remove out case 2 Remove Door Assembly 3 Remove five screws at the base plate Front 3 EA Back 2 EA 4 Disconnect the lead wires from filter 5 Disconnect all the lead wires from main board 6 Disconnect the MGT high voltage lead wire and turn table motor lead wire 7 Lift up the cavity and disconnect the fan motor lead wire CAUTION BE CAREFUL NOT TO DAMAGE ...

Page 17: ...m hook F POWER BOARD AND INVERTER MODULE AND SUCTION GUIDE Figure 12 1 Separate cavity and base plate 2 Remove air guide 3 Unfasten the screws 4 Lift up the power board inverter module and suction guide G SENSOR DUCT REMOVAL Figure 13 1 Remove out case 2 Unfasten the sensor duct screw 3 Disconnect sensor lead wire 4 Pull the sensor duct out Figure 12 Figure 13 ...

Page 18: ...nt microwave leakage tighten the mounting screws properly making sure there is no gap between the waveguide and the magnetron I REMOVING THE TURNTABLE MOTOR 1 Remove the turntable and turntable roller rest 2 Lay the unit down on its back 3 Remove the turntable motor cover The turntable base cover is easily removed by pinching the four parts with a wire cutting 4 Disconnect the leadwire from the tu...

Page 19: ...THE LATCH BOARD 3 INSTALLATION AND ADJUSTMENT OF THE LATCH BOARD TO THE OVEN ASSEMBLY Mount the latch board to the oven assembly Adjust the latch board in the arrow direction so that oven door will not have any play in it when the door is closed Tighten the mounting screw Check for play in the door by pushing the door release button Door movement should be less than 0 5 mm 1 64 inch Don t push the...

Page 20: ...ould indicate an closed circuit 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 Whe...

Page 21: ...y to repair the inverter board nor try to make any adjustments to the board Check wiring to the inverter 1 Unplug the oven s main power supply 2 Visually inspect 4 connectors on the inverter board CN701 CN702 CN703 E701 to see whether there are any signs of failure due to loose wires bad crimping sign of overheating etc 1 Measure the resistance Ohm meter scale Rx1 Filament terminal 2 Measure the r...

Page 22: ...e dry 4 The oven will not generate microwave energy for the first 28 seconds of the sensor cooking cycle 1 Disconnect sensor connector from micom computer board 2 Measure resistance terminal to terminal Select the ohm scale on the meter NOTE MAKE SURE THE LEAD WIRES ARE IN THE CORRECT POSITION WHEN REMOVING THE LEAD WIRES FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES NOTE When testin...

Page 23: ...nce Ohm meter scale R x 1000 Normal Approx ON 0 ohm OFF ohms Abnormal Infinite or several ohms Normal Approx 50 150 ohms Abnormal Infinite or several ohms Normal Approx 2 4K ohms Abnormal Infinite or several ohms 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 WHEN REMOVING THE WIRE LEADS FROM THE ...

Page 24: ...d or the interlock monitor switch Malfunction of the Inverter the magnetron the fan motor or the circuit board PROBLEMS CAUSES NOTES If the fuse is blown by an improper switch operation replace the defective switches and the fuse at the same time After replacing the defective switches with new ones make sure that they are correctly connected Check for microwave energy leakage according to 1 ADJUST...

Page 25: ...r of I O CON from the circuit board does the unit still operate GOOD GOOD Replace the circuit board PROBLEM B FAN motor and oven lamp turn on When the door is closed and START key is touched Check the interlock switches Replace the micro switches Defective RELAY or poor connection of relay Replace RELAY or correct the connection NO NO YES NO NO YES YES ...

Page 26: ...ck 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 flicker 8 Some of the indicators do no light up 9 The clock does not k...

Page 27: ...uilt up in your body Micom model only CONDITION Microwave oven does not work Inserting many plugs into one outlet and using them at the same time blown fuse or breaker Microwave oven plug is not inserted tightly Output power is too low Low AC input voltage Food temperature is too low Using metallic ware and allowing it to touch the oven wall Sparks occur Inconsistent intensity of microwave by thei...

Page 28: ...ight does not turn on after setting cooking cycle 11 Display time of day does not reappear when cooking is finished TROUBLE 1 The following visual conditions indicate a probable defective control circuit CONDITION CHECK RESULT CAUSE REMEDY 1 No input can be programmed Continuity No continuity Defective PCB assembly Loose connection Replace PCB assembly Connect them tightly Check the conn ection be...

Page 29: ... B Assembly Check continuity of monitor switch with door closed Check continuity of primary switch with door opened Disconnect one side of the lead wires connected from Inverter Replace fuse 2 Fuse does not blow No continuity Continuity No continuity Defective power supply cord Replace power supply cord Defective thermostat Replace thermostat Check continuity of thermostat Check continuity of powe...

Page 30: ...door closed Check the con nection between CN1 connector and PCB assembly TROUBLE 3 Display shows all figures set but oven does not start cooking while desired program times are set and START pad is touched TROUBLE 4 Oven seems to be operating but little heat is produced in oven load NOTE Simple test of power output conducted by heating one liter water for one min if available Minimum 8 5 C tempera...

Page 31: ...er level Abnormal Defective PCB assembly Replace PCB assembly Disconnect the lead wires from relay and check continuity relay Operate the unit TROUBLE 5 No microwave oscillation even though oven lamp and fan motor run Display operates properly NOTE Make sure the wire leads correct position When Removing the lead wires from the parts be sure to grasp the connector not the wires When removing the ma...

Page 32: ... 31 INTRODUCTION EXPLODED VIEW ...

Page 33: ... 32 DOOR PARTS 14970A 14026A WTP002 13806A 13213A 13552A 13536A 13581A 268711 WTP002 23506A 13551A 15006A ...

Page 34: ... 33 CONTROLLER PARTS 268711 WTP002 23506A 13551A ...

Page 35: ... 34 OVEN CAVITY PARTS 33112U WTT022 Model LRMM 1430SW Model LRMM 1430SB W107 33390G 35889A WSZ185 36549S WTP013 33052A 13806F 647781 ...

Page 36: ... 35 LATCH BOARD PARTS WSZ085 43500A 466001 43501A 466003 466001 ...

Page 37: ... 36 OVEN INTERIOR PARTS WTT028 WTT021 54974T 56501A 56930V 56912B 43500A 56324A WSZ002 ...

Page 38: ... 37 BASE PLATE PARTS 35264A 568772 568771 56549F 56851H 56201A 50FZZA 54980A 43501A 65006B 63302A WTT021 WTT028 WTT034 WSZ002 268712 WTT028 WTT028 WTT028 55900A 54974S 55238A 568711 56411A ...

Page 39: ...W1K004C SWITCH MICRO R 3B73362F 466003 6600W1K004B SWITCH MICRO R 3B73361E 50FZZA 3B74133K FUSE DRAWING R 3B74133H 54974S 4974W1A014A GUIDE SUCTION R 54974T 4810W1A079A BRACKET SENSOR R 54980A 4B73792B SUPPORTER R 55238A 4974W1A013A GUIDE AIR R 55900A 2B72125A FAN S 56201A 6201W1A008F FILTER ASSEMBLY CIRC R 56324A 6324W1A002B MAGNETRON R 56411A 6411W1A027A POWER CORD ASSEMBLY R 6411W1A027B 56501A ...

Page 40: ...NG PAN HEAD R WTP013 1TPL0402418 SCREW TAPPING PAN HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT034 1TTL0403418 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R S SERVICE PARTS ...

Page 41: ...BOARD LATCH R 43501A 3501W1A030A BOARD ASSEMBLY LATCH R 466001 6600W1K004C SWITCH MICRO R 3B73362F 466003 6600W1K004B SWITCH MICRO R 3B73361E 50FZZA 3B74133K FUSE DRAWING R 3B74133H 54974S 4974W1A014A GUIDE SUCTION R 54974T 4810W1A079A BRACKET SENSOR R 54980A 4B73792B SUPPORTER R 55238A 4974W1A013A GUIDE AIR R 55900A 2B72125A FAN S 56201A 6201W1A010C FILTER ASSEMBLY CIRC R 56324A 6324W1A005A MAGNE...

Page 42: ...PL0402418 SCREW TAPPING PAN HEAD R WTT021 1TTL0402418 SCREW TAPPING TRUSS HEAD R WTT022 1TTL0402422 SCREW TAPPING TRUSS HEAD R WTT028 1TTL0402818 SCREW TAPPING TRUSS HEAD R WTT034 1TTL0403418 SCREW TAPPING TRUSS HEAD R PART NO DESCRIPTION SVC ALTER R S SERVICE PARTS ...

Page 43: ... 42 SCHEMATIC DIAGRAM OF P C B ...

Page 44: ... 43 PRINTED CIRCUIT BOARD KEY PCB MAIN PCB ...

Page 45: ... 22NF D 50V 80 20 F Y5V TA26 R C62 0CK2230K948 CAPACITOR FIXED CERAMIC HIGH DIELECTRIC 22NF D 50V 80 20 F Y5V TA26 R C63 0CK2230K948 CAPACITOR FIXED CERAMIC HIGH DIELECTRIC 22NF D 50V 80 20 F Y5V TA26 R C65 0CK2230K948 CAPACITOR FIXED CERAMIC HIGH DIELECTRIC 22NF D 50V 80 20 F Y5V TA26 R C80 0CK2210K518 CAPACITOR FIXED CERAMIC HIGH DIELECTRIC 220PF D 50V 10 B Y5P TA26 R C81 0CK2210K518 CAPACITOR F...

Page 46: ...0TRFC90021A Q73 0TR107009AE TRANSISTOR BIPOLARS KRA107M KEC TP TO92M 50V 100MA R 0TRFC90021A Q74 0TR107009AE TRANSISTOR BIPOLARS KRA107M KEC TP TO92M 50V 100MA R 0TRFC90021A Q75 0TR107009AE TRANSISTOR BIPOLARS KRA107M KEC TP TO92M 50V 100MA R 0TRFC90021A Q98 0TR107009AE TRANSISTOR BIPOLARS KRA107M KEC TP TO92M 50V 100MA R 0TRFC90021A Q99 0TR107009AE TRANSISTOR BIPOLARS KRA107M KEC TP TO92M 50V 100...

Page 47: ...RESISTOR FIXED CARBON FILM 1M OHM 1 6 W 5 TA26 R R75 0RD2004F608 RESISTOR FIXED CARBON FILM 2M OHM 1 6 W 5 TA26 R R80 0RD2202F608 RESISTOR FIXED CARBON FILM 22K OHM 1 6 W 5 TA26 R R81 0RD2202F608 RESISTOR FIXED CARBON FILM 22K OHM 1 6 W 5 TA26 R R82 0RD2202F608 RESISTOR FIXED CARBON FILM 22K OHM 1 6 W 5 TA26 R R83 0RD2202F608 RESISTOR FIXED CARBON FILM 22K OHM 1 6 W 5 TA26 R R84 0RD2202F608 RESIST...

Page 48: ...P NO 3828W5S3066 May 2003 Printed in Korea ...

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