Brother HL-1070 - B/W Laser Printer Service Manual page 88

M-5 Insufficient output from high-voltage power supply unit
Possible cause Step
High-voltage 1
contact
2
M-6 SR PCB failure
Possible cause Step
SR bias contact 1
Ditto 2
M-7 Fixing heater temperature failure
Possible cause Step
Poor thermistor 1
harness contact
Blown thermal 2
fuse
Thermistor 3
failure
Halogen heater 4
lamp failure
Check
Do any of the terminals on the
high-voltage contacts have dirt
or contact burns?
Check the connection of the
harness between the high-
voltage power supply and the
driver PCB is OK.
Check
Do any of the terminals on the
SR contacts have dirt or
contact burns?
Check the connection of the
harness between the SR PCB
and the driver PCB.
Check
Are the connectors on the
erase lamp PCB and the high-
voltage power supply PCB
secured correctly?
Remove the fixing unit and
measure the resistance
between the input connectors.
Is it open circuit?
Is the thermistor installed
properly?
Remove the fixing unit and
measure the resistance of the
fixing unit lamp. Is it open
circuit?
IV-24
Result Remedy
Yes Clean the high-voltage contact.
Yes Replace the high-voltage
power supply PCB.
No Reconnect the harness
between the high-voltage
power supply and the driver
PCB.
Result Remedy
Yes Clean the SR bias contact.
Yes Replace the SR PCB.
Result Remedy
No Connect the connectors
securely.
Yes Replace the fixing unit.
Yes Replace the fixing unit.
No Reinstall the thermistor
properly.
Yes Replace the halogen heater
lamp.