Brother DCP-7055 Service Manual page 123

■ Black horizontal stripes
Step
Dirt on the electrodes of the drum
1 unit and the machine body
Bend of tray ground spring
2
Scratch and Dirt on the heat roller
3
(horizontal stripes at 53.4 mm)
High voltage power supply PCB
4
ASSY failure
5 Main PCB failure
CAUTION :
• Image defects which appear periodically may be caused by failure of a roller. Specify
the cause referring to the diameter of the rollers or pitch which appears in the image as
shown in the table below
No.
1 Develop roller
2 Exposure drum
3 Heat roller in the fuser unit
4 Pressure roller ASSY in the fuser unit
User Check
• Clean the inside of the machine and the corona wire in the drum unit.
• When the horizontal stripes at 94.2 mm are intervals, replace the
drum unit with a new one.
• The paper tray ground terminal provided in the machine body may
be dirty. Clean the contact with a dry cloth.
• Toner attached on the develop roller (horizontal stripes at 32.5 mm)
This problem will disappear by printing approximate 10 pages.
If the same problem occurs, replace the toner cartridge.
Cause
Bottom surface of Paper tray
Paper tray ground terminal
Fig. 2-13
Parts name
2-86
Remedy
Clean the electrodes of the drum unit and
machine body. (Refer to
12.)
(1) Correct bending of the tray ground spring.
(2) Replace the paper tray.
Replace the fuser unit.
Replace the high voltage power supply
PCB ASSY.
Replace the main PCB ASSY.
Diameter
appears in the image
16 mm
Ø
30 mm
Ø
17 mm
Ø
25 mm
Ø
Fig. 2-11, Fig. 2-
The pitch which
32.5 mm
94.2 mm
53.4 mm
78.5 mm
Confidential