Read Panasonic NN-C781JF Service Manual online
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1.
Oven is dead.
Fuse is OK.
No display and no operation at all.
2.
No display and no operation at all.
Fuse is blown.
3.
Oven does not accept key input(Program)
4.
Oven lamp and fan motor turn on when oven is
plugged in with door closed.
5.
Timer starts count down but no microwave oscil-
lation.
(No heat while oven lamp and fan motor turn on)
6.
Oven can program but timer does not start count-
down.
7.
Microwave output is low. Oven takes longer time
to cook food.
8.
Turntable motor turns on when door is opened.
9.
Loud buzzing noise can be heard.
10.
Turntable motor does not rotate.
11.
Heater does not turn on.
1. Key input is not insequence
2. Open or loose connection of membrane key pad
to DPC (Flat cable)
3. Shorted or open membrane key board
4. Defective DPC
1. Misadjustment or loose wiring of secondary
latch switch
2. Defective secondary latch switch
1. Off-alignment of latch switches
2. Open or loose connection of high voltage circuit
especially magnetron filament circuit
NOTE: Large contact resistance will bring lower
magnetron filament voltage and cause
magnetron to lower output and/or be in-
termittent.
3. Defective high voltage component
HV Inverter Power Supply (u)
Magnetron
4. Open or loose wiring of power relay B (RY-1)
5. Defective primary latch switch
6. Defective DPC or power relay B (RY-1)
1. Open or loose wiring of secondary latch switch
2. Off-alignment of secondary latch switch
3. Defective secondary latch switch
1. Decrease in power source voltage
2. Open or loose wiring of magnetron filament
circuit.(Intermittent oscillation)
3. Aging change of magnetron
1. Shorted primary latch switch
1. Loose fan and fan motor
1. Open or loose wiring of turntable motor
2. Defective turntable motor
1. Defective heater
2. Defective power relay 4 (RY4)
3. Defective DPC
Check fan motor when thermal cutout is defec-
tive.
Check adjustment of primary, secondary latch
switch and short switch including door.
Refer to inverter PCB Troubleshooting
SYMPTOM
CAUSE
CORRECTIONS
Refer to operation procedure.
Refer to DPC troubleshooting.
Adjust door and latch switches.
Adjust door and latch switches.
Check high voltage component according to
component test procedure and replace if it is
defective.
Refer to DPC troubleshooting.
Adjust door and latch switches.
Consult electrician
1. Open or loose lead wire harness
2. Open thermal cutout (Cavity)
3. Defective DPC
1. Shorted lead wire harness
2. Defective primary latch switdh (NOTE 1)
3. Defective short switch (NOTE 1)
4. Defective Inverter Power Supply (U)
Refer to component test procedure
NOTE 1: All of these switches must be replaced at the same time.
Check continuity of power relay (RY1)’s contacts (between 1 and 2) and if it has continuity,
replace power relay B (RY-1) also.
(Trouble 2) Other troubles
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