Epson DFX-8500 Service Manual page 188

DFX-8500
Symptom
The +37 VDC (VP1 /
VP2) line is dead.
The +37 VDC (VP3) line
is dead.
5-14
Table 5-5. C204 PSB/PSE Board Component Repair 2/3
Cause
The main switching FETs
QF101 is defective.
IC101 is defective.
The main switching FETs
QF201 is defective.
Q201 is defective.
Q202 is defective.
Checkpoint
Observe the voltage
waveform between the
drain side and GND.
Pin 5 (FB) must be HIGH
then observe the voltage
waveform between pin 2
(VOUT) and pin 12
(GND) of IC101.
Observe the voltage
waveform between the
drain side and GND.
Observe the voltage
waveform between the
collector side and GND.
Observe the voltage
waveform between the
collector side and GND.
Solution
Replace QF101.
Replace IC101.
Replace QF201.
Replace Q201.
Replace Q202.
Rev. B