Brother HL-1850 Service Manual page 232

CHAPTER 6 TROUBLESHOOTING
I-16 Black spots
Possible cause
Drum unit
Drum
connection
failure
Fixing unit
High-voltage
power supply
PCB failure
User Check
(1) If the problem is not solved after printing a few pages, the drum unit may have
glue from label stock on the photosensitive drum surface. Refer to Step 1 in the
table below and NOTE
(2) The drum unit may be damaged. Install a new drum unit.
Step Check
1 Are the spots at 94mm
intervals?
(The problem is not solved
after printing a few pages.)
2 Is the contact between the
drum unit and printer body
connected correctly?
3 Are the spots at 79mm
intervals?
(The problem is not solved
after printing a few pages.)
4 Is the problem solved after
replacing the high-voltage
power supply PCB?
in the previous page.
Result
Yes
No
Yes
Yes
6-48
Remedy
1) If toner or glue
remains stuck, wipe it
off gently with a
cotton swab. (Refer
to NOTE in the
previous page.)
2) If the photosensitive
drum is scratched or
deteriorated
(exposed), replace
the drum unit.
Clean contact electrode
both on the drum unit
and in the printer body.
1) Check and clean the
heat roller with a
cloth dampened with
alcohol.
2) Replace the fixing
unit.
Replace the high-
voltage power supply
PCB.
Ground
contacts
(8)