LQ-670 Service Manual
Rev. A 5-1
5
Symptom Condition Cause Checkpoint Solution
Printer goes to
error state. Fatal error. +42V monitor
circuit is defective. Check the voltage of 3 or 4
pin in CN3.
•If the voltage is normal,
CPU is defective.
Replace the main
board or power
supply circuit board.
Carriage control
circuit is defective. Check the output signal of
pin 1, 8,11,18 and input
signal of pin 5, 6,16,17 of
IC3.
•If the phase signal of the
motor is not input, gate
array IC25 is defective.
•If the drive waveform is
not output, IC7 is defective.
Pin 1 of IC3
Pin 5 of IC3
Figure 5-13. Waveform of
the Carriage Motor Drive
Replace the main
board or IC3.
Abnormal
printing Print head
control is
abnormal.
Print head control
circuit is defective. Measure the base voltage
of Q1∼Q24 and collector
voltage.
•When the input signal is
not detected on the base
side, gate array is
defective.
•If the output waveform is
not detected in the
collector, driver transistor is
defective.
Base
Collector
Figure 5-14. Head Drive
Signal
Replace the main
board or
corresponding
transistor.
Table 5-12. Repairing C214 Main Board (Con.)