REV.-A
TROUBLESHOOTING
Table 5-7. SAMA Board Unit Repair (Cont.)
Problem
Carriage
operates
abnormally.
Symptom
Carriage
does not
operate at
all.
Carriage
operation is
unstable
(lack of
torque).
Cause
IC7A is
defective.
IC2A is
defective.
IC2B
is
defective.
Reference
voltage
generating
circuit is
faulty.
Checkpoint
At IC7A, check the input waveform at pin 59 and the
output signals at pins 60, 61, 62, and 63.
Check input signal and output signal.
At IC2B, check the input signal at pin 5 and the output
waveform at pin 1.
Check transistors Q30, Q31, and Q35.
Solution
Replace
IC7A.
Replace
IC2A.
Replace
IC2B.
Replace
Q30, Q31,
and Q35.
LQ-510
5-17
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