Specifications

LQ-2080 Revision A
Troubleshooting Repairing the C273 Main Board 43
Table 5-3. Repairing the C272MAIN Board (2/3) Table 5-4. Repairing the C272MAIN Board (3/3)
Problem Cause Checkpoint Solution
The printer does
not operate at all.
CR1 is
defective.
Check the oscillator signal at
pins 26 or 27 of the CPU.
If the signal is
not correct,
replace IC4 (or
replace the main
board).
Otherwise,
replace CR1.
Carriage operation
is abnormal.
IC11 or IC4 is
defective.
• Check input signal
waveform (CH1) at pins 6,
5, 17, and 16 of IC11.
• Check output signal
waveform (CH2) at pins 8,
1, 18, and 11 of IC11.
If the input
signal is not
correct, replace
IC4 (or replace
the main board).
If the output
signal is not
correct, replace
IC11.
IC4 is
defective.
Check the output signal at
pins 1 to 4 of IC4.
If there is no
output signal,
replace IC4 (or
replace the main
board).
Problem Cause Checkpoint Solution
Paper feed is
abnormal.
IC3 is defective
or IC12 is
defective.
• Check input signal waveform
at pin 8 of IC12.
• Check output signal waveform
at pins 1, 2, 23, and 24 of
IC12.
If the input
signal is not
correct, replace
IC1 or IC2 (or
replace the main
board). If the
input signal is
correct and the
output signal is
not correct,
replace the
IC11.
No data is
printed.
IC4 is
defective.
Check the output signal
waveform at pin 15 of IC4.
If this signal is
not output,
replace IC4 (or
replace the main
board).
A particular
dot fails to
print.
IC3 is
defective or
one of the head
drive
transistors is
defective (Q1 -
Q24).
• Check the voltage waveform
(CH1) at port HD1 - HD24 of
IC3.
• Check the voltage waveform
(CH2) for each transistor.
If the head drive
signal is not
output, replace
IC3 (or replace
the main board).
If the head drive
signal is output
from the head
drive transistors,
replace the head
drive transistor.