Panasonic NN-SE795S, Service Manual

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8.4.3. NN-SD765S/SD755S
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 13 voltage Abnormal IC10 and/or IC11
Normal=5V IC1, CX320, Display
No key input 1 Light touch switch continuity Abnormal Light touch switch
Normal IC1
No beep sound 1 IC1 pin 20 voltage Abnormal IC1
Normal=5V BZ210, Q210
No microwave oscillation at any power 1 IC1 pin 27 voltages while operation at high
power Abnormal IC1
Normal=5V
→
Step2
2 Collector of Q227 voltage Abnormal Q227 and/or Q225, Q226
Normal 0.7V
→
Step3
3 Short circuit between collector of Q227
and emitter of Q225 Still not turn on RL1
RL1 turns on Q227 and/or Q225, Q226
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. Interlock Switch
2. D.P.C. /Power Relay
Normal=120V
→
Step2
2 Unplug CN701 (3 pin) connector and
measure pin1 voltage Abnormal=0V D.P.C.
Approx. AC 3V Magnetron
25
NN-SE795S / NN-ST785S / NN-ST775S / NN-ST765S / NN-SD765S / NN-SD755S