Brother HL 1240 - B/W Laser Printer Service Manual page 130

CHAPTER 6 TROUBLESHOOTING
M-5 Insufficient output from high-voltage power supply unit
Possible cause
High-voltage
contact
High-voltage
power supply
PCB
M-6 Fixing heater temperature failure
Possible cause
Poor thermistor
harness contact
Blown thermal
fuse
Thermistor
failure
Halogen heater
lamp failure
M-7 BD failure
Possible cause
Harness
connection
failure
Step Check
1 Do any of the terminals on the
high-voltage contacts have dirt
or contact burns?
2 Check the connections of the
connector between the high-
voltage power supply and the
engine PCB are secured
correctly.
Step Check
1 Is the contact of connector P6
on the engine PCB good?
2 Remove the fixing unit and
measure the resistance of the
thermistor. Is it open circuit?
3 Is the thermistor installed
properly?
4 Remove the fixing unit and
measure the resistance of the
halogen heater lamp. Is it
open circuit?
Step Check
1 Is connector P10 on the main
PCB secured correctly?
Result
Yes
Yes
No
Result
No
Yes
Yes
No
Yes
Result
No
Yes
6-20
Remedy
Clean the terminals.
Replace the high-voltage
power supply PCB
Reconnect the connector
between the high-voltage
power supply and the engine
PCB.
Remedy
Reconnect the connector.
Replace the fixing unit.
Replace the fixing unit.
Reinstall the thermistor
properly.
Replace the halogen heater
lamp.
Remedy
Reconnect the connector
securely.
Replace the laser unit.