Troubleshooting For Fuser Unit Problems; Fuser Unit Failure; Troubleshooting For Laser Unit Problems; Laser Unit Failure - Brother DCP-L5500D Service Manual

4.8 Troubleshooting for Fuser Unit Problems

4.8.1 Fuser unit failure

Step
Connection failure of the center
1
thermistor harness
Connection failure of the side
2
thermistor harness
Connection failure of the heater
3
harness
Connection failure of the eject
4
sensor harness
5 Eject sensor PCB failure
Low-voltage power supply PCB
6
failure
7 Fuser unit failure
8 Main PCB failure
Note:
• Turn the power switch OFF and then ON again. Leave the machine for 15 minutes.
This problem may then be cleared.
• The machine may recover from the error, when the test printing of the maintenance
mode for service personnel is started. However, conducting this operation while the
heater has not yet cooled may cause the fuser unit to melt. Be careful.

4.9 Troubleshooting for Laser Unit Problems

4.9.1 Laser unit failure

<User Check>
• Turn ON the power switch, then open the front cover and the back cover. Leave the
machine for a while to remove condensation.
Step
Ground plate contact failure
1
2 Laser unit attachment failure
Connection failure of the laser unit
3
flat cable
4 Laser unit failure
5 Main PCB failure
Cause
Reconnect the center thermistor harness.
Reconnect the side thermistor harness.
Reconnect the heater harness.
Reconnect the eject sensor harness.
Replace the eject sensor PCB ASSY.
Replace the low-voltage power supply PCB
ASSY.
Replace the fuser unit.
Replace the main PCB ASSY.
Cause
Retighten the screws to secure the laser unit
ground plate.
Reattach the laser unit.
Reconnect the laser unit flat cable.
Replace the laser unit.
Replace the main PCB ASSY.
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Remedy
Remedy
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