Trouble Related To Digital Programmer Circuit - Panasonic NN-GD693S Service Manual

8.4.

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 pin 13 voltage
1 Touch switch continuity
1 IC1 pin 1 voltage
1 IC1 pin 28 voltage while operation
2 Collector of Q229 voltage
1 IC1 pin 27 voltages while operation at high
power
2 Collector of Q220 voltage
3 Short circuit between collector of Q220
and emitter of Q225
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 D. P. C. CN3
25
RESULT CAUSE/CORRECTIONS
→Step2
Normal
Open Replace D.P.C. or Fuse Pattern
Abnormal 0V L.V.T.
→Step3
Normal
Abnormal Q10, ZD10
Normal=5V IC1, Display
Abnormal Touch switch
Normal IC1
Abnormal IC1
Normal=5V BZ210, Q210
Abnormal IC1
→Step2
Normal=5V
Abnormal Q229
Normal 0.7V RY2
Abnormal IC1
→Step2
Normal=5V
Abnormal Q220 and/or Q221, Q222, Q225
→Step3
Normal 0.7V
Still not turn on RY1
RY1 turns on Q220 and/or Q221, Q222, Q225
Normal Display
Abnormal IC1
Normal IC1
Abnormal Display
Abnormal=0V 1. Latch Switch
2. D.P.C. /Power Relay
→Step2
Normal=120V
Abnormal=0V D.P.C.
Approx. AC 3V Magnetron
NN-GD693S