Unit Repairing Of The Main Board - Epson LQ-570e Service Manual

EPSON LQ-570e/LQ-580

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.
Symptom
The printer does not operate at all. The CPU does not operate.
The carriage does not operate
The carriage operates abnormally.
at all.
The paper feeds abnormally. The paper is not fed at all.
The self test printing is not
Self test printing is abnormal. executed or a particular dot is
not printed.
Data from the host computer is Data corruption occurs when
printed incorrectly. the interface is used.
Troubleshooting
Table 3-2. Repair of the C293PSB/PSE
Condition Cause
The reset circuit is not
operational.
Selection control ROM is
abnormal.
The CPU is defective.
IC9 is defective.
IC 10 is defective.
Any one transistor of Q2 -
Q26 is defective.
IC4 or CPU (IC7) is
defective.
Unit Repairing of the MAIN Board
The table below lets you troubleshoot problems with the main board (C293MAIN). 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.
Check point
Verify the voltage waveforms for the +5VDC line
(IC6, pin 7) and for the reset signal (IC6, pin 5).
Verify the signal at pin 22, IC2 or pin 11, IC8 which
changes between HIGH and LOW.
Verify the oscillator signal at pin 38 or 39 of the CPU
(IC7).
Verify the CR motor phase control signals at pin 5, 6,
16,17, and motor drive signals at pin 1, 8, 11, 18 of
IC9
Verify the PF motor phase control signals at pin 16,
27 and motor drive signals at pin 6, 7, 8, 9 of IC10.
Verify the printhead drive signal at the corrector and
base of Q2 - Q26.
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Revision C
Solution
Replace the C293MAIN board.
Replace the C293MAIN board.
Replace the C293MAIN board.
Replace the C293MAIN board.
Replace the C293MAIN board.
Replace the C293MAIN board.
Replace the C293MAIN board.
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