Troubleshooting According To Image Defect - Brother FAX-2840 Service Manual

3.6.2 Troubleshooting according to 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 those of the machine
2 Developing bias failure
High voltage power supply PCB
3
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. Turn 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.
Replacing the used toner cartridge with a relatively new used toner
cartridge can cause this problem.
- Check that condensation has not formed in the machine or the
installation location is appropriate.
Cause
2-65
Remedy
Clean the electrodes of the drum unit and
those of the machine. (Refer to
and Fig. 2-11.)
Reset the counter for the developer roller.
Replace the high voltage power supply PCB
ASSY.
Replace the laser unit.
Replace the main PCB ASSY.
Fig. 2-10
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