Troubleshooting For Fuser Unit Problems; Fuser Unit Failure; Troubleshooting For Laser Unit Problems; Laser Unit Failure - Brother DCP-7090 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 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
1
2
3
4
5
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
Laser unit attachment failure
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
ASSY.
Replace the fuser unit.
Replace the main PCB ASSY.
Reattach the laser unit.
Reconnect the laser unit flat cable.
Reconnect the polygon motor harness.
Replace the laser unit.
Replace the main PCB ASSY.
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Remedy
Remedy
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