Panasonic Inverter NN-A574SBBTQ - Digital Programmer Circuit Troubleshooting

22
12.6 Digital programmer circuit troubleshooting
H97, H98 appears in
the display window.
Check oven input
current.
Check magnetron
filament continuity.
DPC board/Power Relay
Loose wiring.
Latch Switch.
DPC control signal
Magnetron*
Stop!!
If all the previous checks
are OK, there may be an
H.V. Inverter fault.
NOTE:
DANGER
HIGH
VOLTAGE
Less than 0.4A
More than 0.5A
Open
OK
Refer to component
test procedures
*Check the continuity of the magnetron
filament. Check the filament is not shorted to the
magnetron case.
NOTE: try to the inverter
power supply.
on the inverter circuit
board. It is very dangerous to repair or adjust this
preset without correct test equipment.
Do not attempt to repair the inverter circuit board,
replace the inverter circuit board with a new unit.
DO NOT REPAIR
DO NOT ADJUST
THE PRESET VOLUME
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
2IC10 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
Power relay (RY2 ) does not
operate
1 IC-1 pin 23 during
operation
Abnormal
Normal 5V
2 Create a short circuit
between pin 6 and pin
16 of IC-2
RY2 does not turn on RY2
RY2 turns on IC-220
No microwave oscillation 1 IC-1 pin 18 and 16
during high power
operation
Abnormal IC-1
Normal 18 - 5V
16 - 5V
Step 2
2 Q221 transistor
Dark or unclear display 1 Replace display Abnormal Display
Normal IC-1
Missing segments in display Replace IC-1 Abnormal IC-1
Normal Display