Panasonic NN-CT577SEPG, Service Manual

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12.6 Troubleshooting inverter by microwave oven input current
This is an alternative way to test the inverter circuit by monitoring the input current to the microwave oven.
The microwave oven must be set in self test mode to activate the self diagnostic failure code system.
12.7 Digital programmer circuit troubleshooting
Alternate way to troubleshoot oven with AC Ampere meter used
H95, H97, H98, H99 appears in display window a short time after start key is pressed and no microwave oscillation with AC Ampere
meter used for troubleshooting.
SYMPTOM STEP CHECK RESULT CORRECTION
No display when the microwave
oven is first plugged in.
Microwave oven is dead
1 Fuse pattern on DPC Normal STEP 2
Open (Note1) Shorted circuit ZNR-
LVT-Lamp
2 IC10 pin 9
12V line Abnormal 0V IC10
Normal 12V Step 3
3 IC-1 pin 73
(Emitter of Q10) Abnormal ZB10 Q10 Ribbon cable
Normal 5V Step 4
4 IC-1 pin 27
(pin 15 of IC220) Abnormal IC-220
Normal IC1 CX1
NOTE
The procedure for repairing the fuse pattern on the DPC is as follows:
1. Fuse pattern PF2 open circuit
a) Remove the jumper wire PF2
b) Move the jumper wire PF3 into the postion of PF2 and solder inplace.
Replace the DPC if both the fuse pattern PF2 and PF3 are open circuit.
Note: After repairing the fuse pattern on the DPC, check the varistor for any burns and measure the winding
resistance of the low-voltage transformer primary coil.
No key input
1 Push button switch Abnormal Push button switch
Normal IC-1
No beep sound 1 IC1 pin 12 Abnormal IC-1
Normal IC-220 BZ310