LQ-670 Service Manual
Rev. A
5-1
4
Refer to the following table for repairing the main board.
Symptom Condition Cause Check point Solution
The printer does
not work at all. Reset signal is
not canceled. Defective
operation of the
reset circuit
After the power is turned on,
check 1pin of IC12 stays
LOW for a while.
•Reset signal is generated in
the IC21 and sent to the
CPU and gate array.
Replace the main
board.
VOUT signal is
output. Check if +5V is normal and
also check pin 7 and pin 8 of
CN3.
Replace the
power supply
board
CPU does not
work. Clock signal is
not generated. Check the signal of pin 26
and 27 in the IC11 (clock
signal of CPU)
Figure 5-11.Clock Signal of
CPU
Replace the main
board or CRU1.
PROM(IC8) or
Flash
ROM(IC7) is
defective.
Check the waveform of 22
pin of IC 7 or IC8.
•If there is no waveform,
gate array(IC10) is defective.
Figure 5-12. Chip Select
Signal
Replace the main
board.
Table 5-11. Repairing the C214 Main Board