Troubleshooting For Fuser Unit Problems; Fuser Unit Failure; Troubleshooting For Laser Unit Problems; Laser Unit Failure - Brother DCP-L8400CDN Service Manual

4.8

Troubleshooting for Fuser Unit Problems

4.8.1

Fuser unit failure

Step
1
2
3
4
5
6
7
8
Note:
- Turn the power OFF and then ON again. After the machine is left as it is for about 10
minutes, this problem may be resolved.
- If test print is performed in maintenance mode for service personnel, the machine may
recover from the error. However, note that if this operation is performed while the heater
has not cooled down, the fuser unit may melt.
4.9

Troubleshooting for Laser Unit Problems

4.9.1

Laser unit failure

Step
1
2
3
4
Cause
Connection failure of the
center thermistor harness
Connection failure of the side
thermistor harness
Connection failure of the
heater harness
Connection failure of the eject
sensor PCB harness
Eject sensor PCB failure
Low-voltage power supply
PCB failure
Fuser unit failure
Main PCB failure
Cause
Connection failure of the laser
unit flat cable
Connection failure of the
polygon motor harness
Laser unit failure
Main PCB failure
Reconnect the center thermistor harness.
Reconnect the side thermistor harness.
Reconnect the heater harness.
Reconnect the eject sensor PCB harness.
Replace the eject sensor PCB ASSY.
Replace the low-voltage power supply PCB
unit.
Replace the fuser unit.
Replace the main PCB ASSY.
Reconnect the laser unit flat cable.
Reconnect the polygon motor harness.
Replace the laser unit.
Replace the main PCB ASSY.
2-121
Remedy
Remedy
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