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5-8

CAUTIONS

1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE

OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH
VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE
HIGH VOLTAGE TRANSFORMER. (SEE PAGE 2-1)

2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER

OF WATER IN CONTAINER) IN THE OVEN.

COMPONENTS

TEST PROCEDURE

RESULTS

HIGH VOLTAGE
TRANSFORMER
(Wire leads removed)

MAGNETRON
(Wire leads removed)

1. Measure the resistance.

(Ohm-meter scale: Rx1)
¥ 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)
¥ Between Filament terminal

2. Measure the resistance.

(Ohm-meter scale: Rx1000)
¥ Filament to chassis

Approx.: 1.4 ½
Approx.: 90 ½
Less than: 0.1 ½

Normal: °
Normal: °

Normal: Less than 1 ½

Normal: °

PRIMARY  
TERMINAL

SECONDARY 
TERMINAL

FILAMENT 
WINDING
TERMINAL

COMPONENT TEST PROCEDURE

Summary of Contents for MS-1907C

Page 1: ...MICROWAVE OVEN SERVICE MANUAL MODEL MS 1907C CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL ...

Page 2: ...ity of the microwave radiation leakage emitted by the microwave oven should not exceed 5 mW cm2 Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NECESSARY MEASURING INSTRUMENTS TESTER VOLTS DC AC Ohmmeter Microwave survey meter Holaday HI 1500 HI 1501 Narda 8100 8200 Inch scale 600 cc non conductive material beaker glass or plastic inside d...

Page 3: ...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 cause...

Page 4: ...en 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 ÆT 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 ...

Page 5: ...REMOVAL 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 gui...

Page 6: ...t of 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 turntable shaft VERY CAREFULLY 3 Lay the unit down on its back 4 Remove the turntable motor cover The...

Page 7: ...ount 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 moves smoothly af...

Page 8: ...osed 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 open ...

Page 9: ...ONENTS TEST PROCEDURE RESULTS HIGH VOLTAGE TRANSFORMER Wire leads removed MAGNETRON Wire leads removed 1 Measure the resistance Ohm meter scale Rx1 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 Between Filament terminal 2 Measure the resistance Ohm ...

Page 10: ...le 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 gask...

Page 11: ...NOTE If the fuse is blown check the primary the secondary and the monitor switches H V D and H V C before 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 Normal Abnormal ...

Page 12: ...tch 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 C 2 3 B 2 M A 1 2 A B C A Turn on Approx 25 K Turn Off B FAN MOTOR Wire leads removed TURNTABLE MOTOR Wire leads removed Normal Abnormal or several Normal App...

Page 13: ...oading 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 their characteristics 1 Use plastic wrap or lid 2 Stir once or twice while cooking soup cocoa or milk etc Uneven cooking Ceramic ware trimmed in gold or silver powde...

Page 14: ...former Malfunction of the monitor switch Replace fuse primary monitor and secondary 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 voltage capacitor and operate the unit Replace fuse TROUBLE 1 Oven lamp does not turn on when the timer knob is pushed with doo...

Page 15: ...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 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...

Page 16: ...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 4 O...

Page 17: ...6 1 DOOR PARTS SUCTION GUIDE MAIN PARTS CONTROL PANEL PARTS INTERIOR PARTS BASE PLATE PARTS OVEN CAVITY PARTS EXPLODED VIEW INTRODUCTION ...

Page 18: ...6 2 13720D 13352A 14970A 13581A 14026A 13213A 13552A 13536A DOOR PARTS ...

Page 19: ...6 3 23572A 249401 24510L 249402 24970A 250201 24781T 26549T WTP015 CONTROL PANEL ASSEMBLY PARTS ...

Page 20: ...6 4 33052M 36549S 34036W WTP013 368771 35889A 33390G 34930W 33112U WTT021 948503 948502 OVEN CAVITY PARTS WSZ092 ...

Page 21: ...6 5 WSZ084 56549F WTT037 43501A 54974S 466001 WTT028 466003 466001 56930V 50FZZA WTT028 56912B WSZ002 55900A 56201A 568771 43500A SUCTION GUIDE PARTS ...

Page 22: ...6 6 INTERIOR PARTS 56324A WSZ002 WSZ062 56411A ...

Page 23: ...6 7 WTT028 WSZ002 50CZZH 56851C 647781 647781 56851D 56170D 948501 63302A WSZ002 63303A 54810C BASE PLATE PARTS ...

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