Epson LQ-570e, Service Manual

Page: 67 / 129

EPSON
LQ-570e/LQ-580
Revision
C
Troubleshooting Unit
Repairing of the MAIN Board
67
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 (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.
Table
3-2. Repair of the C293PSB/PSE
Symptom Condition Cause Check
point
Solution
The
printer does not operate at all. The CPU does not operate.
The
reset circuit is not
operational.
Verify
the voltage waveforms for the +5VDC line
(IC6,
pin 7) and for the reset signal (IC6, pin 5).
Replace
the C293MAIN board.
Selection
control ROM is
abnormal.
Verify
the signal at pin 22, IC2 or pin 11, IC8 which
changes
between HIGH and LOW.
Replace
the C293MAIN board.
The
CPU is defective.
Verify
the oscillator signal at pin 38 or 39 of the CPU
(IC7).
Replace
the C293MAIN board.
The
carriage operates abnormally.
The
carriage does not operate
at
all.
IC9
is defective.
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
Replace
the C293MAIN board.
The
paper feeds abnormally.
The
paper is not fed at all.
IC
10 is defective.
Verify
the PF motor phase control signals at pin 16,
27
and motor drive signals at pin 6, 7, 8, 9 of IC10.
Replace
the C293MAIN board.
Self
test printing is abnormal.
The
self test printing is not
executed
or a particular dot is
not
printed.
Any
one transistor of Q2 -
Q26
is defective.
Verify
the printhead drive signal at the corrector and
base
of Q2 - Q26.
Replace
the C293MAIN board.
Data
from the host computer is
printed
incorrectly.
Data
corruption occurs when
the
interface is used.
IC4
or CPU (IC7) is
defective.
-- Replace
the C293MAIN board.