Oki B 4100 Maintenance Manual page 260

(5) No –8 V output
Is there oscillation
waveform at VCE of Q1?
Is the voltage across
C19 at 9 V or more?
Is the output voltage
40055101TH Rev.4
Start
No
Yes
No
Yes
No
of C20 at -8V.
Yes
End
1. Q1 short circuit
2. Q3 short circuit
Replacement
3. R9 open circuit
4. D8, D9 or D10 short circuit
1. D10 open circuit
Replacement
2. R23 short circuit
1. IC2 fault
2. C20 short circuit
Replacement
3. Short circuit on load side
260 /