Panasonic NNSN960S, Service Manual

Page: 22 / 33

8.4. Trouble related to Digital Programmer Circuit
SYMPTOM STEP CHECK RESULT CAUSE/CORRECTIONS
No display when oven is first plugged
in 1 Fuse pattern of D.P.C. Normal
→
Step2
Open Replace D.P.C. or Fuse
Pattern
2 Low voltage transforment (L.V.T.)
secondary voltage Abnormal 0V L.V.T.
Normal
→
Step3
3 IC1 pin 23 voltage Abnormal Q11, ZD11, Q10, ZD10
Normal=3.3V IC1, CX320, Display
No key input 1 Membrane switch continuity Abnormal Membrane switch
Normal IC1
No beep sound 1 IC1 pin 29 voltage Abnormal IC1
Normal=3.3V BZ210, Q210
Power relay RY2 does not turn on
even though the program had been set
and the start button is tapped 1 IC1 pin 2 voltage while operation Abnormal IC1
Normal=3.3V
→
Step2
2 Collector of Q225 voltage Abnormal Q225
Normal 0.7V RY2
No microwave oscillation at any power 1 IC1 pin 1 voltages while operation at high
power Abnormal IC1
Normal=3.3V → Step2
2 Collector of Q224 voltage Abnormal Q224 and/or Q220, Q222,
Q231
Normal 0.7V RY1
Dark or unclear display 1 Replace display and check operation Normal Display
Abnormal IC1
Missing or lighting of unnecessary
segment 1 Replace IC1 and check operation Normal IC1
Abnormal Display
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 1 Unplug CN702 (2 pin) connector and
measure voltage between terminals Abnormal=0V 1. Latch Switch
2. D.P.C. /Power Relay
Normal=120V
→
Step2
2 Unplug CN701 (3 pin) connector and
measure pin1 voltage of connector CN3 Abnormal=0V D.P.C.
Approx. AC 3V Magnetron
22
NN-SN960S