Brother HL-3450CN Service Manual page 316

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 Page
Main Causes
The dustproof glass of the laser unit is smeared with toner or foreign particles.
Countermeasures
Clean the dustproof glass. (See
(1) Remove the OPC belt cartridge and toner cartridges.
(2) Remove the dustproof glass from the laser unit.
(3) Clean the dustproof glass.
I-8 Vertical White Band
Phenomenon
White band appears in the vertical direction of printed image as shown in
Page 8-45.
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
(3) If the oil adhesion is excessive, replace the OPC belt cartridge and drum cleaner with new
ones. (See Section 4.1 and 4.5 of Chapter
8-45.
Section 2.8 of Chapter 6.)
Transfer unit
Transfer drum
Fig. 8-10
Section 4.8 of Chapter
6.)
8-53
HL-3450CN SERVICE MANUAL
print sample (8) of
6.)