Service manual

Troubleshooting
5-14
EPSON FX-880/FX-1180 Service Manual
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.
Figure 5-3. Power Supply Board Layout
Table 5-11. Repairing the C229 PSB/PSE Board
Symptom Condition Possible
Cause
Checkpoint Solution
The printer
does not
operate.
Fuse F1 is
blown.
Examine the fuse to see if it’s
blown.
Replace the
power supply
board.
The +35 V line
does not test at
the correct
voltage.
The transformer
coil (T1) is
open.
Measure the resistance of
the T1 transformer coil.
Replace the
power supply
board.
. Switching FET
(Q1) is
defective.
Check the voltage waveform
between the source and
drain of Q1.
Replace the
power supply
board.
Transform er
R e g u la to r IC
CN1
CN2
Switching FET
Fuse
D iode Bridge
Photo-coupler