Unit Repairing Of The Power Supply Board - Epson FX 890 - B/W Dot-matrix Printer Service Manual

3.3 UNIT REPAIRING OF THE POWER SUPPLY BOARD

This section is necessary only for servicers who repair to the component level. Servicers who
perform only board replacement can ignore this section.
The table below lets you troubleshoot problems with the power supply board
(C229PSB/PSE/PSH). The table provides various symptoms, likely cases, and checkpoints.
Checkpoints include waveforms, resistance, and other values to be checked to evaluate the
operation of each component.
Symptom Condition
The printer +35V line is
dose not defective.
operate at
all.
Rev. B
Table 3-7. Repair of the C229PSB/PSE/PSH
Cause
Fuse F1 is Check that the fuse is not blown.
blown.
Transformer Check the coil of transformer using
(T1) is open. a multimeter.
Switching Check for the proper waveform at
FET (Q1) is the drain of Q1.
defective.
Q2 or Q3 is Check for the proper waveform at
defective. the collector of Q2 or Q3.
FX-1180/FX-880 Service Manual
Checkpoint
Figure 3-10. Drain of Q1
Figure 3-11. Collector of Q2/Q3
Chapter 3 Troubleshooting
Solution
Replace the
C229PSB/
PSE/PSH
board.
Replace the
C229PSB/
PSE/PSH
board.
Replace the
C229PSB/
PSE/PSH
board.
Replace the
C229PSB/
PSE/PSH
board.
3-11