8.4.2. EXCEPT NN-SD691S & NN-SD671S
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 Q10, ZD10
Normal=5V IC1, Display
No key input 1 Membrane switch continuity Abnormal Membrane switch
Normal IC1
No beep sound 1 IC1 pin 61 voltage Abnormal IC1
Normal=5V BZ210, Q210
Power relay RY2 does not turn on
even though the program had been
set and the Start pad is tapped
1 IC1 pin 21 voltage while operation Abnormal IC1
Normal=5V →Step2
2 Collector of Q223 voltage Abnormal Q223
Normal 0.7V RY2
No microwave oscillation at any
power
1 IC1 pin 27 voltages while operation at high
power
Abnormal IC1
Normal=5V →Step2
2 Collector of Q220 voltage Abnormal Q220 and/or Q221, Q222, Q225
Normal 0.7V →Step3
3 Short circuit between collector of Q220
and emitter of Q225
Still not turn on RY1
RY1 turns on Q220 and/or Q221, Q222, Q225
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 D. P. C. CN3
Abnormal=0V D.P.C.
Approx. AC 3V Magnetron
26
NN-SD691S / NN-ST681S / NN-SD671S / NN-ST671S / NN-ST661S / NN-ST661B / NN-ST661W / NN-ST651B / NN-ST651W
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