Brother HL-L5000D Service Manual page 136

 Fogging
Step
Toner amount detection sensor
1
PCB (light reception) failure
2 Relay front PCB failure
High-voltage power supply PCB
3
failure
4 Main PCB failure
Note:
• This problem tends to occur when the life of the drum unit or toner cartridge is expiring.
<User Check>
- Check the usage environment of the machine. Using the machine in
hot-humid or cold-dry conditions can cause this problem.
- Check that the acid paper is not used.
- This problem may disappear after printing multiple sheets of paper.
- Replace the toner cartridge with a new one.
- Replace the drum unit with a new one.
Cause
2-110
Remedy
Replace the toner amount detection sensor
PCB ASSY (light reception).
Replace the relay front PCB ASSY.
Replace the high-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
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