Troubleshooting Image Defect - Brother HL-600 Service Manual

2.2

Troubleshooting Image Defect

Procedures to follow in response to specific image defects.
I-1 Light
Possible cause Step
Poor contrast 1
Toner sensing 2
failure (toner
cartridge side)
Toner sensing
3
failure
(printer side)
Drum GND
4
connection failure
Transfer electrode
5
contact failure
Transfer failure
6
Developing bias
7
contact failure
High-voltage
8
power supply
failure
Driver PCB
9
failure
Check
Is the contrast adjustment dial in
the center of click position?
Is the problem solved when 4 or 5 pages
are printed after the cartridge is replaced
with a full one?
Can printing be started with the drum unit
removed?
Is the drum shaft grounded when the drum unit is
installed?
Is there continuity between the transfer roller shaft
and the transfer electrode on the external drum
unit?
Is the problem solved when the transfer roller is
replaced?
Are the developing bias contacts between
the printer body and the drum unit soiled?
Remove the main cover and measure the
voltage at the electrode plate at the right side
face while printing with the interlocks defeated.
Is the voltage correct?
Perform the same check as step 8 above.
Result
No
Yes
Yes
No
Yes
Yes
Yes
No
No
IV - 4
Remedy
Set it to the center click
position or reasonable
position.
The wiper of the toner
cartridge is defective.
Replace the toner cartridge.
Toner sensor failure.
Check if the toner sensor
needs cleaning and check
the toner sensor connection.
Clean contact electrodes
between the printer body and
the drum shaft of drum unit .
Replace the drum unit.
Replace the drum unit.
Clean the terminals of both sides.
Check the harness connection
between the high-voltage
power supply and the driver PCB.
If the connection is normal,
replace the high-voltage power
supply PCB.
Replace the driver PCB.