Troubleshooting Image Defect - Brother DCP-L8400CDN Service Manual

4.3.2

Troubleshooting image defect

Image defect related problems are end user recoverable if following the User Check items. If
the same problem occurs again, follow each procedure in the order of the number described in
the Step column in the tables below.
■
Light on the whole page
Step
1
2
3
4
5
6
7
< User Check >
- Check the machine's environment. High temperature and high humidity
or low temperature and low humidity conditions can cause this problem.
- If the whole page is light, toner save mode may be ON. Turn OFF the
toner save mode.
- Adjust the color calibration from the control panel.
- Replace the drum unit with a new one.
- Replace the toner cartridge with a new one.
- Replace the belt unit with a new one.
- Wipe the scanner windows of the laser unit with a soft, lint-free cloth.
- Leave the machine for a while as the power remains ON.
(Condensation)
- Check if paper is not damp.
Cause
Dirt on the electrodes of the
main body and the drum unit
Dirt on the electrodes of the
high-voltage power supply
PCB
Dirt on the density sensor
Density sensor failure
Fuser unit failure
High-voltage power supply
PCB failure
Main PCB failure
Clean the electrodes of the main body and
the drum unit.
(Refer to Fig. 2-7
Clean the electrodes of the high-voltage
power supply PCB.
Clean the density sensor.
Replace the registration mark sensor unit.
Replace the fuser unit.
Replace the high-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
2-97
Remedy
(P2-55), Fig. 2-8 (P2-55).)
Confidential