Troubleshooting Image Defect - Brother DCP-7055 Service Manual

3.6.2 Troubleshooting image defect

Image defect related problems are user recoverable if following the User Check items. If the
same problem occurs, follow each procedure in the order of the number described in the
Step column in the tables below.
Light
■
Step
Dirt on electrodes of the drum unit
1 and machine body
2 Develop bias failure
High voltage power supply PCB
3
ASSY failure
4 Laser unit failure
5 Main PCB failure
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. Off the toner
save mode.
• Adjust the density by the Density Adjustment.
• Replace the drum unit with a new one.
• Replace the toner cartridge with a new one. If remove the used
toner cartridge and replace a relatively new used toner cartridge,
this case is caused.
Cause
2-80
Remedy
Clean the electrodes of the drum unit and
machine body. (Refer to
12.)
Reset the counter of develop roller.
Replace the high voltage power supply
PCB ASSY.
Replace the laser unit.
Replace the main PCB ASSY.
Fig. 2-11, Fig. 2-
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