Digital Programmer Circuit - Panasonic NN-CT577SEPG Service Manual

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.
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.
12.7 Digital programmer circuit troubleshooting
SYMPTOM
No display when the microwave
oven is first plugged in.
Microwave oven is dead
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
No beep sound
STEP CHECK
1 Fuse pattern on DPC
2 IC10 pin 9
12V line
3 IC-1 pin 73
(Emitter of Q10)
4 IC-1 pin 27
(pin 15 of IC220)
1 Push button switch
1 IC1 pin 12
21
RESULT
Normal STEP 2
Open (Note1)
Abnormal 0V
Normal 12V Step 3
Abnormal
Normal 5V Step 4
Abnormal
Normal IC1 CX1
Abnormal
Normal
Abnormal
Normal IC-220 BZ310
CORRECTION
Shorted circuit ZNR-
LVT-Lamp
IC10
ZB10 Q10 Ribbon cable
IC-220
Push button switch
IC-1
IC-1