Brother HL-5240 Service Manual page 166

CHAPTER 4 TROUBLESHOOTING
(I-16) Black spots
Possible cause
Drum unit
Drum
connection
failure
Fuser 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 exposure drum surface. Refer to Step 1 in the table
below and NOTE in the previous page.
(2) The drum unit may be damaged. Install a new drum unit.
Step Check
1 Are the spots at 94.2mm
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?
Result
Yes 1) If toner or glue
2) If the exposure drum
No Clean contact electrode
both on the drum unit
and in the printer body.
Yes 1) Check and clean the
2) Replace the fuser
Yes Replace the high-voltage
power supply PCB.
4-52
Remedy
remains stuck, wipe it
off gently with a
cotton swab. (Refer
to NOTE in the
previous page.)
is scratched or
deteriorated
(exposed), replace
the drum unit.
heat roller with a cloth
dampened with
alcohol.
unit.
Confidential
Ground
contacts
(7)