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CAUTIONS 

 
 
 

 

• DO NOT operate on a 2-wire extension cord during 

repair and use. 

• NEVER TOUCH any oven components or wiring during 

operation. 

• BEFORE TOUCHING any parts of the oven, always 
remove the power plug from the outlet.   
• For about 30 seconds after the oven stops, an electric 

charge remains in the high voltage capacitor. When 

replacing or checking, you must discharge the high 

voltage capacitor by shorting across the two terminals 

with an insulated screwdriver. 

 

 

 

• 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 this 

P.C.B.  

• NEVER operate the oven with no load. 

• NEVER injure the door seal and front plate of the oven 

cavity. 

• NEVER put iron tools on the magnetron. 

• NEVER put anything into the latch hole and the 

interlock switches area.` 

 
 
 
 
 
 
 

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 during repair.

 

MICROWAVE RADIATION 

Personnel should not be exposed to the 

microwave energy which may radiate from the 

magnetron or other microwave generating 

device if it is improperly used or connection. 

All input and output microwave connections, 

waveguide, flange and gasket must be secure 

never operate the device without a microwave 

energy absorbing load attached. 

Never look into an open waveguide or antenna 

while the device is energized. 

• Proper operation of the microwave oven 

requires that 

the magnetron 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. 

 

THE OVEN IS TO BE SERVICED 
ONLY 
BY PROPERLY QUALIFIED SERVICE
PERSONNEL.

 

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Summary of Contents for MM720CFA-PM0C

Page 1: ...MICROWAVE OVEN MODEL 700W 220V50Hz SERVICE MANUAL CAUTION BEFORE SERVICING THE UNIT READTHE SAFETY PRECAUTIONS IN THIS MANUAL MM720CFA PM0C...

Page 2: ...r 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 for any service te...

Page 3: ...M 4 1 CIRCUIT DESCRIPTION 4 2 SERVICE INFORMATION 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST 5 2 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 TROUBLE SHOOTING PROCEDURES 5 4 COMMON BR...

Page 4: ...atch hole and the interlock switches area 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 tak...

Page 5: ...gth among the molecule and changed to microscopic microwave heating Microwave heating not only concerned the nature of the matter itself but also closely connected with the electric field strength and...

Page 6: ...and flat surface at least 10 cm 4 inches from the wall 7 Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent interference BEFORE YOU BEGIN READ THE FOLLOWING INSTRUC...

Page 7: ...OR CLOSED CONDITION ON SECONDARY BL WH FUSE FILTER ASS Y BR GE BL N L SINGLE PHASE ONLY POWER SUPPLY GE N L BL SWITCH BK NO INTERLOCK MONITOR COM NC M BL TM 2 SWITCH UPPER INTERLOCK PRIMARY BK SWITCH...

Page 8: ...r is also directed into the oven to exhaust the vapor in the oven through the upper plate Timer starts rotating 3 2 volts AC is generated from the filament winding of the high voltage transformer This...

Page 9: ...icrowave leakage Check for microwave leakage after every servicing The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 5 mW cm2 Always start measuring...

Page 10: ...n 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...

Page 11: ...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 th...

Page 12: ...Measure the insulating resistance with a multi meter or a mega ohmmeter The value should not less than 2 mega ohm Otherwise part examination should be taken at once Such as checking whether the motor...

Page 13: ...itor pole and the cabinet FIG 5 6 should be checked If the resistance value between the capacitor pole and the cabinet is the capacitor is normal Then check the earth of the magnetron s two filament t...

Page 14: ...t the upper screw Loosen out the screw push the door close to the oven to hook the door hook with the plastic parts then tighten the screw again If the leakage is larger at the right below then adjust...

Page 15: ...cutout is playing its protective role and you should check whether the fan is working in normal Turn off the oven pull out the power plug take down the outer case discharge the capacitor then turn th...

Page 16: ...Turntable Motor Wire leads removed Measure the resistance Ohm meter scale R 1000 Normal Approx 3 2k Abnormal or Several NOTE z A MICROWAVE LEAKGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICE...

Page 17: ...Insert the plug securely 3 Change the weave 5 The oven can heat within 2 3 minutes but can not heat from the fourth minutes 1 The winding of the fan motor in open circuited 2 The fan falls off 3 The...

Page 18: ...ck the electrical continuity 2 2 Make sure the power cord is pulled out and the high voltage capacitor is discharged before the electrical continuity check 2 3 Set the ohmmeter to Low Resistance range...

Page 19: ...3 Check the following items before turning the oven ON 1 Proper door closing seal choke surfaces and hinges 2 No outer case damage 3 Proper interlock and monitor operations Insulation Resistance Test...

Page 20: ......

Page 21: ...MM720CFA PM0C...

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