Repairing The Power Supply Circuit Board - Epson FX-880 Service Manual

Troubleshooting

Repairing the Power Supply Circuit Board

This section describes how to identify and repair problems with the C229 PSB/PSE/PSH power supply
board. The table below lists symptoms, likely causes, and solutions to various problems. The checkpoints
refer to waveforms, resistances, and other values that should be present when the component is working
properly. Sometimes, the same solution may be offered for an entire class of problems; in this case, the
checkpoints should be used for reference or as aids to further investigation.
Symptom Condition
The printer The +35 V line
does not does not test at
operate. the correct
voltage.
.
5-14
Figure 5-3. Power Supply Board Layout
Table 5-11. Repairing the C229 PSB/PSE Board
Possible
Cause
Fuse F1 is
blown.
The transformer
coil (T1) is
open.
Switching FET
(Q1) is
defective.
Checkpoint
Examine the fuse to see if it's
blown.
Measure the resistance of
the T1 transformer coil.
Check the voltage waveform
between the source and
drain of Q1.
EPSON FX-880/FX-1180 Service Manual
Solution
Replace the
power supply
board.
Replace the
power supply
board.
Replace the
power supply
board.