Brother DCP-L8400CDN Service Manual page 139

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One color spots or dirt
< User Check >
- Check if damp paper is used.
- Refer to the User's guide and remove the dirt on the exposure drum using a cotton swab.
- Replace the drum unit with a new one.
- Replace the toner cartridge with a new one.
- Replace the belt unit with a new one.
Step
1 Paper dust is accumulated
2 Dirt on the exposure drum
3 Toner filter is clogged
4 Scratch and dirt on fuser unit
5 High-voltage power supply
PCB failure
Note:
Image defects which occur periodically may be caused by a failure of the rollers.
Use the diameters of the rollers or the pitches which appear in images shown in the table
below to identify the cause of the problem.
<Pitches on images caused by rollers>
Part name
Develop roller
Exposure drum
Heat roller of the fuser unit
Pressure roller of the fuser unit
Cause
Clean the paper dust cleaning roller.
(Refer to
Perform drum cleaning.
(Refer to
Clean the toner filter.
Replace the fuser unit.
Replace the high-voltage power supply PCB
ASSY.
appears in the image
30 mm
94 mm
78.5 mm
78.5 mm
2-109
Remedy
Fig. 2-14 (P2-108).)
"2.2 Drum Cleaning" in Chapter
The pitch which
5.)
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