Trouble Related To Digital Programmer Circuit - Panasonic NN-GF560M Service Manual

NN-GF560M
9.4.

Trouble related to Digital Programmer Circuit

SYMPTOM
No display when oven is first plugged
in
No key input
No beep sound
Power relay RY2 does not turn on
even though the program had been set
and the [start] pad is tapped
No microwave oscillation at any power
Dark or unclear display
Missing or lighting of unnecessary
segment
H95/H97/H98 appears in window and
oven stops operation.Program High
power for 1 minute and conduct
following test quickly, unless
H95/H97/H98 appears and oven stops
STEP CHECK
1 Fuse pattern of D.P.C.
2 Low voltage transforment (L.V.T.)
secondary voltage
3 IC1 pin23 voltage
1 Membrane switch continuity
1 IC1 pin 1 voltage
1 IC1 pin 2 voltage while operation
2 Short circuit between collector and emitter
of Q223
1 IC1 pin 20 voltages while operation at high
power
2 Collector of Q220 voltage
1 Replace display and check operation
1 Replace IC1 and check operation
1 Unplug CN702 (2 pin) connector and
measure voltage between terminals
2 Unplug CN701 (3 pin) connector and
measure pin1 voltage of CN3
22
RESULT CAUSE/CORRECTIONS
Normal →Step2
Open Replace D.P.C. or Fuse
Pattern
Abnormal 0V L.V.T.
→Step3
Normal
Abnormal Q11, ZD11,Q10,ZD10
Normal=3.3V IC1, CX320, Display
Abnormal Membrane switch
Normal IC1
Abnormal IC1
Normal=3.3V BZ210, Q210
Abnormal IC1
→Step2
Normal=3.3V
Still not turn on RY2
RY2 turns on Q223
Abnormal IC1
→Step2
Normal=3.3V
Abnormal Q220 and /or
Q225,Q221,Q227
Normal 0.7V →Step3
Normal Display
Abnormal IC1
Normal IC1
Abnormal Display
Abnormal=0V 1. Latch Switch
2. D.P.C. /Power Relay
→Step2
Normal=220V
Abnormal=0V D.P.C.
Approx. AC 3V Magnetron