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DFX-8500
Rev. B
5-1
4
Table 5-5. C204 PSB/PSE Board Component Repair 2/3
Symptom Cause Checkpoint Solution
The +37 VDC (VP1 /
VP2) line is dead.
The main switching FETs
QF101 is defective.
Observe the voltage
waveform between the
drain side and GND.
Replace QF101.
IC101 is defective. Pin 5 (FB) must be HIGH
then observe the voltage
waveform between pin 2
(VOUT) and pin 12
(GND) of IC101.
Replace IC101.
The +37 VDC (VP3) line
is dead.
The main switching FETs
QF201 is defective.
Observe the voltage
waveform between the
drain side and GND.
Replace QF201.
Q201 is defective. Observe the voltage
waveform between the
collector side and GND.
Replace Q201.
Q202 is defective. Observe the voltage
waveform between the
collector side and GND.
Replace Q202.