Brother HL-1020 Service Manual page 74

I-3 Completely blank
Possible cause Step
Developing bias 1
contact failure
Drum unit 2
Drum unit failure 3
Scanner harness 4
connection failure
Main / Panel 5
sensor PCB
connection failure
Scanner unit 6
failure
Check
Are the developing bias
contacts between the printer
body and drum unit dirty?
Are the drum shaft and drum
electrode of the printer body
connected correctly?
Is the problem solved after the
drum unit is replaced?
Is the scanner harness
connected securely?
Is there any play in the
connection?
Are printing signals being input
to the scanner?
Is the problem solved after the
main PCB or the panel sensor
PCB replaced?
Scanner interlock lever
damaged.
Scanner mirror is broken or
loose.
IV-7
Result Remedy
Yes Clean the electrodes
at both sides.
Yes Clean the shaft and
the electrode.
No Check the connection
between the shaft and
the electrode.
Yes Replace the drum
unit.
No Reconnect the
connector properly.
Yes Replace the main
PCB or the panel
sensor PCB.
Yes Replace the scanner
unit.
No Replace the high-
voltage power supply
PCB.
HV.GND
contacts
(Fig.4-5)