Brother HL-2400C Service Manual page 292

I-7 White Line (2)
Phenomenon
Vertical white line appears from the leading edge to the trailing edge of the printed image
as shown in print sample (7) of
Main Causes
The dustproof glass of the scanner unit is smeared with toner or foreign particles.
Countermeasures
Clean the dustproof glass.
1) Remove the OPC belt cartridge and toner cartridges. (See
VI.)
2) Remove the dustproof glass from the scanner unit.
3) Clean the dustproof glass. (See
I-8 Vertical White Band
Phenomenon
White band appears in the vertical direction of printed image as shown in
of Fig.8-2.
Main Causes
Silicone oil adhering to the transfer drum.
Transfer Drum
Adhered silicon oil
Countermeasures
1) Wipe off the oil adhering to the transfer unit and its perimeter.
2) Replace the transfer drum with a new one. (See Section
3) If the oil adhesion is excessive, replace the OPC belt cartridge and drum cleaner with
new ones. (See Section 2.1
Fig.8-2.
Section 1.2.8 of Chapter
Transfer Unit
Fig.8-7
and 2.5 of Chapter VI.)
VIII-47
Section 2.1 of Chapter
VI.)
print sample (8)
Drum Cleaner
Transfer Drum
2.8 of Chapter VI.)