Brother HL-7050 Service Manual page 240

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
thermostat
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
CN7 on the engine PCB good?
2 Remove the fixing unit and
measure the resistance of
thermostat. 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 P7 on the main
PCB secured correctly?
Result
Yes Clean the terminals.
Yes Replace the high-voltage
power supply PCB
No Reconnect the connector
between the high-voltage
power supply and the engine
PCB.
Result
No Reconnect the connector.
Yes Replace the fixing unit.
Yes Replace the fixing unit.
No Reinstall the thermistor
properly.
Yes Replace the halogen heater
lamp.
Result
No Reconnect the connector
securely.
Yes Replace the laser unit.
6-30
Remedy
Remedy
Remedy