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• 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.

• The water is contained in a cylindrical borosilicate glass

vessel having a maximum material thickness of 3 mm
and an outside diameter of approximately 190mm.

• The oven and 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 the water to rise by a

value ∆ T of (10±2)°K is measured, where T is the time
in seconds and T is the temperature rise.   The initial
and final water temperatures are selected so that the
maximum difference between the final water
temperature and the ambient temperature is 5°K.

• The microwave power output P in watts is calculated

from the following formula :

4187 x (T)

T

is measured while the microwave generator is

operating at full power. Magnetron filament heat-up
time is not included. (about 3 sec)

• The  water is stirred to equalize temperature throughout

the vessel, prior to measuring the final water
temperature.

• Stirring devices and measuring instruments are

selected in order to minimize addition or removal of
heat.

A. OUTER CASE REMOVAL

1) Disconnect the power supply cord from the outlet.

2) Remove the screws from the rear of the case.

The outer case must be moved backward to be lifted
off.

B. POWER SUPPLY CORD

1) Remove the outer case.
2) Disconnect two terminals, and remove one screw of

the ground terminal.

C. CONTROL PANEL ASSEMBLY

1) Open the door.
2) Remove the screws for the ground and securing the

control panel.

3) Disconnect the leadwire from motor timer.
4) Lift up and pull out control panel assembly carefully

from the cavity.

CAUTION: DISCHARGE THE HIGH VOLTAGE 

CAPACITOR BEFORE SERVICING

(Refer to page 2-1)

5-3

WATER LOAD

TURNTABLE

MEASUREMENT OF MICROWAVE POWER OUTPUT

P =

Remove the screw

Lift up and pull out control panel

DISASSEMBLY AND ADJUSTMENT

Summary of Contents for MA-6400B2

Page 1: ...OWAVE OVEN SERVICE MANUAL MODEL MA 6400W2 MA 6400B2 CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL website http www lgservice com e mail http www lgeservice com techsup h...

Page 2: ...ration 2 proper door closing 3 seal and sealing surfaces arcing wear and other damage 4 damage to or loosening of hinges and latches 5 evidence of dropping or abuse C Before turning on microwave power...

Page 3: ...ING 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 DISASSEM...

Page 4: ...t Weight Shipping weight Control Complement Nameplate Location Accessories DESCRIPTION MA 6400W2 MA 6400B2 120 Volts AC 60 Hz 910 Watts 8 5A Single phase 3 wire grounded 600 Watts full microwave power...

Page 5: ...ron 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 in...

Page 6: ...cal parts of the unit Do not install the oven next to a conventional surface unit or above a conventional wall oven 5 Use microwave oven in an ambient temperature less than 104 F 40 C 6 Place the micr...

Page 7: ...the desired setting 2 The door can be opened during the cooking process by pushing the Door Open Button The timer will stop and the microwave activity will cease When the door is closed cooking will...

Page 8: ...ER SWITCH H V TRANSFORMER H V CAPACITOR N AC 120V 60Hz IMPORTANT SAFETY NOTE THE COMPONENTS IN SHADED AREAS ON THIS SCHEMATIC DIAGRAM INCORPORATE SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM MICROWA...

Page 9: ...pplied to the magnetron to heat the magnetron filament through two noise preventing choke coils A high voltage of approximately 2100 volts AC is generated in the secondary of the high voltage transfor...

Page 10: ...ion leakage MEASURING MICROWAVE ENERGY LEAKAGE Pour 275 15cc of 20 5 C 68 9 F water in a beaker which is graduated to 600 cc and place the beaker on the center of the turntable Set the energy leakage...

Page 11: ...test probe must be removed no faster 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 read...

Page 12: ...e ambient temperature is 5 K The microwave power output P in watts is calculated from the following formula 4187 x T T is measured while the microwave generator is operating at full power Magnetron fi...

Page 13: ...lacing the door be sure to check that the primary switch monitor switch and secondary switch operate normally 2 After replacing the door check for microwave energy leakage with a survey meter Microwav...

Page 14: ...to the magnetron To prevent microwave leakage tighten the mounting screws properly making sure there is no gap between the waveguide and the magnetron G REMOVING THE TURNTABLE MOTOR 1 Remove the turnt...

Page 15: ...owave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage 2 MOUNTING OF THE PRIMARY MONITOR SECONDARY SWITCHES TO THE LATCH BOARD 3 INST...

Page 16: ...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 t...

Page 17: ...TS 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 resi...

Page 18: ...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 i...

Page 19: ...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 sec Normal A B Approx 65 80 ohm B C Approx 10 30 ohm A C Approx 85 105 ohm Abnormal...

Page 20: ...ing 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 lo...

Page 21: ...ondary switches Check continuity of monitor switch with door closed Check continuity of primary switch with door opened Disconnect one side of the wire lead connected from transformer to the high volt...

Page 22: ...able Minimum 8 5 C temperature rise is normal condition CONDITION CHECK RESULT CAUSE REMEDY Output is low Lower than 90 of rating voltage Normal Abnormal Measure the output power Defective magnetron R...

Page 23: ...h voltage capacitor Normal Check high vol tage capacitor Abnormal Defective high voltage diode Replace high voltage diode Normal Check high vol tage diode Abnormal Defective magnetron Replace magnetro...

Page 24: ...DOOR PARTS LATCH BOARD PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS 6 1 EXPLODED VIEW INTRODUCTION...

Page 25: ...6 2 13552A 13213A 13581A 13720D 14970A 14026A 13536A 13352A DOOR PARTS...

Page 26: ...6 3 24781T 23572A 24510L 250201 24970A 249401 26549T CONTROLLER PARTS...

Page 27: ...6 4 33390G 35889A WSZ185 33112U WTP013 36549S 33052A 948502 WTT010 OVEN CAVITY PARTS WTT020...

Page 28: ...6 5 466001 466003 WTT028 466001 43500A 56912B 55262A WSZ085 SUCTION GUIDE PARTS...

Page 29: ...6 6 INTERIOR PARTS 568771 56930V 56411A 54974S 56549F WTT037 WTT028 WSZ002 55900A 56324A WSZ002 55006F 50FZZA...

Page 30: ...6 7 56170D 63302A 63303A WTT021 WSZ002 948501 65006B 65006B 50CZZH WSZ002 54810C 56851D BASE PLATE PARTS...

Page 31: ...Apr 2002 Printed in Korea P NO 3828W5S1905...

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