Brother MFC8420 Service Manual page 247

CHAPTER 6 TROUBLESHOOTING
I-23
Possible cause
Driver setting
Drum unit failure
High-voltage
power supply
PCB failure
I-24
Ghost
User Check
(1) Check the paper used meets the recommended paper specifications. Damp
paper, thick media or rough surfaced paper can cause the problem.
(2) Check the machine's environment. High temperature and high humidity
conditions can cause the problem.
(3) Check that the appropriate media type is selected in the printer driver.
(4) Try installing a new drum unit.
Step Check
1 Is thin paper such as 64g/m
used under the thick paper
mode?
2 Is the problem solved after
replacing the drum unit?
3 Is the problem solved after
replacing the high-voltage
power supply PCB?
Toner specks
User Check
(1) Check the paper used meets the recommended paper specifications. A rough
surfaced paper may cause the problem.
(2) The toner cartridge may be damaged. Install a new toner cartridge.
(3) The drum unit may be damaged, or may be nearly at the end of life. Install a new
drum unit.
Result
2
Yes 1) Change the current mode to
2) Print 5 or 6 blank pages if
Yes Replace the drum unit.
Yes Replace the high-voltage power
supply PCB.
6-52
Remedy
the normal mode from the
driver setting.
this problem occurs.