LG MB-4322AH Service Manual Download | Manualshive

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5-9

COMPONENTS

TEST PROCEDURE

RESULTS

HIGH VOLTAGE
CAPACITOR

HIGH VOLTAGE
DIODE

NOTE :
Some inexpensive meters
may indicate infinite
resistance in both direction.

Measure the resistance.
(Ohm-meter scale: Rx1000)
• Terminal to terminal.

Measure the resistance.
(Ohm-meter scale: Rx1000)
• Terminal to case.

Measure the continuity (Forward).
(Ohm-meter scale: Rx10000)

Measure the continuity (Reverse).
(Ohm-meter scale: Rx10000)

Normal: Momentarily indicates

several ohms, and then
gradually returns to
infinite.

Normal:

∞

Normal: Continuity.
Abnormal:

∞

Normal:

∞

Abnormal: Continuity.

NOTE: When testing the magnetron, be sure to install the magnetron gasket

in the correct position and be sure that the gasket is in good condition.

Antenna

Gasket

Chassis

Filament

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Summary of Contents for MB-4322AH

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MB 4322AH CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL ...

Page 2: ...r and other damage 4 damage to or loosening of hinges and latches 5 evidence of dropping or abuse C Before turning on microwave power for any service test or inspection within the microwave generating compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections D Any defective or misadjusted components in the interlock monitor door seal...

Page 3: ...TING SEQUENCE 4 2 SCHEMATIC DIAGRAM 4 3 CIRCUIT DESCRIPTION 4 4 SERVICE INFORMATION 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST 5 1 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 DISASSEMBLY AND ADJUSTMENT 5 3 INTERLOCK CONTINUITY TEST 5 7 COMPONENT TEST PROCEDURE 5 8 TROUBLE SHOOTING 5 12 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 7 1 CONTENTS ...

Page 4: ...4 39F 60 Min 485 W x 280 H x 406 D mm 332 W x 200 H x 331 D mm 13 5 kg approx 15 0 kg approx Microwave Power for Variable Cooking Power level Max 600W 360W Defrost 90W Grill Combi 1 2 3 Owner s manual Glass tray Rotating ring Grill rack 1 1 ITEM MODEL Power Requirement Power Output Microwave Frequency Magnetron Timer Outside Dimensions Cavity Dimensions Net Weight Shipping weight Control Complemen...

Page 5: ...tron be assembled to the waveguide and cavity Never operate the magnetron unless it is properly installed Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron 2 1 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 du...

Page 6: ...to prevent interference 8 Do not touch the front glass during or after cooking of the Grill and Combination mode This glass is very hot during heater operating 9 Do not operate the oven at microwave and combination mode with Grill rack placed in the cavity when the oven is empty EARTHING INSTRUCTIONS This microwave oven is designed to be used in a fully earthed condition It is imperative therefore...

Page 7: ...ANEL Grill Rack Oven Front Plate Window Door Screen Door Seal Control Panel Safety Door Lock System Turntable Rotating Ring 2 3 1 1 1 POWER CONTROL KNOB Used in selected the desired power level for cooking 2 TIMER KNOB Used to set the cooking time ...

Page 8: ...the food on the rack in the oven and close the oven door 2 Set the function 3 Set the timer to the desired cooking time The turntable begins to rotate cooking starts and the lamp is turned on At the end of the cooking time you will hear a ring sound and the lamp is turned off COMBI COOKING 1 Open the oven door place the food on the rack in the oven and close the oven door 2 Set the 1 2 3 function ...

Page 9: ...4 3 SCHEMATIC DIAGRAM ...

Page 10: ...gnetron filament through two noise preventing choke coils A high voltage of approximately 2100 volts AC is generated in the secondary of the high voltage transformer which is increased by the action of the diode and charging of the high voltage capacitor The negative DC voltage is then applied to the filament of the magnetron WHEN THE DOOR IS OPENED DURING COOKING Both primary switch and secondary...

Page 11: ...ich is graduated to 600 cc and place the beaker on the center of the turntable Set the energy leakage monitor to 2 450 MHz and use it following the manufacturer s recommended test procedure to assure correct result When measuring the leakage always use the 2 inch 5cm spacer supplied with the probe Operate the oven at its maximum output Measure the microwave radiation using and electromagnetic radi...

Page 12: ...ter than 1 inch sec 2 5 cm sec along the shaded area otherwise a false reading may result The test probe must be held with the grip portion of the handle A false reading may result if the operator s hand is between the handle and the probe When testing near a corner of the door keep the probe perpendicular to the surface making sure the probe horizontally along the oven surface this may possibly c...

Page 13: ... the empty vessel are at ambient temperature prior to the start of the test The initial temperature T1 of the water is 10 2 C It is measured immediately before the water is added to the vessel After addition of the water to the vessel the load is immediately placed on the center of the turntable which is in the lowest position and the microwave power switched on The time T for the temperature of t...

Page 14: ...1 Discharge the high voltage capacitor 2 Disconnect the leadwire from magnetron high voltage transformer and capacitor 3 Remove the screw holding the high voltage transformer to the baseplate F FAN MOTOR ASSEMBLY REMOVAL 1 Discharge the high voltage capacitor 2 Disconnect the leadwire from fan motor noise filter and high voltage capacitor 3 Remove the two screws holding the the suction guide ASS Y...

Page 15: ... 5 mW cm2 With a 275 ml water load Make sure that gasket is rigidly attached to the magnetron To prevent microwave leakage tighten the mounting screws properly making sure there is no gap between the waveguide and the magnetron J REMOVING THE TURNTABLE MOTOR 1 Remove the turntable 2 Remove the Rotating Ring 3 Lay the unit down on its back 4 Remove the turntable motor cover The turntable base cover...

Page 16: ...EN 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 door release button while making adjustment Make sure that the latch move...

Page 17: ... closed meter should 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 op...

Page 18: ...S TEST PROCEDURE RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 and Rx100 Primary winding Secondary winding Filament winding 2 Measure the resistance Ohm meter scale Rx1000 Primary winding to ground Filament winding to ground 1 Measure the resistance Ohm meter scale Rx1 Filament terminal 2 Measure the resistance Ohm met...

Page 19: ...r scale Rx1000 Terminal to case Measure the continuity Forward Ohm meter scale Rx10000 Measure the continuity Reverse Ohm meter scale Rx10000 Normal Momentarily indicates several ohms and then gradually returns to infinite Normal Normal Continuity Abnormal Normal Abnormal Continuity NOTE When testing the magnetron be sure to install the magnetron gasket in the correct position and be sure that the...

Page 20: ...e replacing the fuse If the fuse is blown by improper switch operation replace the defective switch and the fuse at the same time Replace just the fuse if the switches operate normally NOTE Make sure heater is fully cooled when tested Measure the resistance Multi meter scale Rx1 Normal Grill heater Approx 50 Ω at 20 30 C Normal more than 200 MΩ Normal Abnormal Measure the resistance with 500V 100M...

Page 21: ...scale R x 1000 Normal Abnormal or several Ω Normal Approx 100 200 Ω Abnormal or several Ω 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 PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES A B C Turn On Turn Off A B Grill Switch Microwave Switch Approx 22 KΩ No...

Page 22: ...el to discharge any static charge built up in your body CONDITION Microwave oven does not work Inserting many plug into one plug outlet and using them at the same time causes overloading 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 occurring Inconsistent intensi...

Page 23: ...ned Disconnect one side of the wire lead connected from transformer to the high voltage capacitor and operate the unit Replace fuse 1 Oven does not operate No continuity No continuity Adjust or replace Malfunction of the primary switch Malfunction of the secondary switch Adjust or replace Check the continuity of the primary switch with door closed Check the continuity of the secondary switch with ...

Page 24: ...ician Check the power source voltage oscillating No continuity No continuity replace Malfunction of the timer switch Faulty thermostat replace Check the continuity of the timer switch contacts Check the continuity of the thermostat CONDITION CHECK RESULT CAUSE REMEDY TROUBLE 4 Grill CONDITION CHECK RESULT CAUSE REMEDY 1 Heater is not operating Abnormal Normal Normal Heater Thermostat Grill Abnorma...

Page 25: ...oking state Check the monitor resistor Abnormal Defective AC relay Replace Normal Check the AC relay Abnormal Open the secondary winding of the high voltage transformer of faulty insulation of filament winding Replace Check H V transformer Abnormal Shorted H V diode Replace Check H V diode Abnormal Faulty capacitor Replace Check H V capacitor Abnormal Faulty magnetron Replace Magnetron TROUBLE 5 O...

Page 26: ...DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS 6 1 EXPLODED VIEW INTRODUCTION ...

Page 27: ...6 2 13581A 14970A 14026A 13552A 13536A 15006A 13213A 13720D 13352A DOOR PARTS ...

Page 28: ...6 3 23572A 249402 26549T 24781T WTP015 249401 CONTROL PANEL PARTS ...

Page 29: ...6 4 33112U 35264A WTT021 33550H 35026G 33052M 340511 36549S WTP013 33390G 35889A WTT021 33808A WSZ184 35300S WNZ015 OVEN CAVITY PARTS ...

Page 30: ...6 5 466003 466001 43501A 43500A 44510A 466001 WSZ085 LATCH BOARD PARTS ...

Page 31: ...6 6 WSZ002 WTT028 WTT028 WSZ062 50FZZA WSZ112 WTT037 50CZZH 56324A 948502 55262A 54810C 55900A 56549F 56411A 56201A 56930V 56930G 568771 54974S 56912B WSZ002 56851D WSZ002 34930W INTERIOR PARTS ...

Page 32: ...6 7 56170D 63302A 63303A WTT021 948501 WSZ002 65006B BASE PLATE PARTS ...

Page 33: ...P NO 3828W5S2624 Jan 2003 Printed in Korea ...

Page 34: ...DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS 6 1 EXPLODED VIEW INTRODUCTION ...

Page 35: ...6 2 13581A 14970A 14026A 13552A 13536A 15006A 13213A 13720D 13352A DOOR PARTS ...

Page 36: ...6 3 23572A 249401 26549T 24781T WTP015 CONTROL PANEL PARTS ...

Page 37: ...6 4 33112U 35264A WTT021 33550H 35026G 33052M 340511 36549S WTP013 33390G 35889A WTT021 33808A WSZ184 35300S WNZ015 OVEN CAVITY PARTS ...

Page 38: ...6 5 466003 466001 43501A 43500A 44510A 466001 WSZ085 LATCH BOARD PARTS ...

Page 39: ...6 6 WSZ002 WTT028 WTT028 WSZ062 50FZZA WSZ112 WTT037 50CZZH 56324A 948502 55262A 54810C 55900A 56549F 56411A 56201A 56930V 56930G 568771 54974S 56912B WSZ002 56851D WSZ002 34930W INTERIOR PARTS ...

Page 40: ...6 7 56170D 63302A 63303A WTT021 948501 WSZ002 65006B BASE PLATE PARTS ...

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