Epson DFX-8500 Service Manual page 193

Table 5-6. C204 MAIN/DRV/DRV-B boards Component Repair 4/7
Symptom
The carriage
The carriage encoder
operates sensor is defective.
abnormally.
Carriage operation is
unstable (due to a
lack of motor torque).
Rev. B
Cause
Observe the carriage encoder sensor
output signal at pins 4 (ENCA) and 3
(ENCB) of CN4 on the C204 MAIN
board.
Check the switching waveform for Q5,
Q6, and Q7.
Checkpoint
TROUBLESHOOTING
Solution
Replace the
carriage encoder
sensor.
Replace the
abnormal transistor.
5-19