Unit Repairing Of The Main Board - Epson FX-880 Service Manual

3.4 UNIT REPAIRING OF THE MAIN 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 main board (C229MAIN). The table
provides various symptoms, likely cases, and checkpoints. Checkpoints include waveforms,
resistance, and other value to be checked to evaluate the operation of each component.
Condition
Symptom
The printer The CPU
dose not dose not
operate at operate.
all.
Rev. A
Table 3-8. Repair of the C229MAIN
Cause
Verify the voltage waveforms for the
+5VDC line (IC1, pin 3) and for the
reset signal (IC1, pin 1) when the
power is on.
The reset
circuit is not
operational.
Figure 3-15. Reset Signal
Verify the signal at pin 22, IC7 or pin
30, IC6 which changes between
HIGH and LOW.
Selection
control ROM
is abnormal
Figure 3-16. Chip Select Signal for
FX-880 Service Manual
Chapter 3 Troubleshooting
Checkpoint
Program ROM
Solution
Replace the
C229MAIN
board.
Replace the
C229MAIN
board.
3-13