Brother MFC-8220 Service Manual page 200

CHAPTER 6 TROUBLESHOOTING
M-6 Fixing heater temperature failure
Possible cause
Poor thermistor
harness contact
Blown thermal
fuse
Thermistor
failure
Halogen heater
lamp failure
M-7
Possible cause
Harness
connection
failure (1)
Harness
connection
failure (2)
M-9 Fixing Unit failure
Possible cause
Poor thermistor
harness contact
Blown thermal
fuse
Thermistor
failure
Halogen heater
lamp failure
Heater harness
connection
failure
Step Check
1 Is the contact of connector
CN7 on the engine PCB good?
2 Remove the fixing unit and
measure the resistance of the
thermal fuse. 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?
Laser Unit failure
Step Check
1 Is the LD harness connector
on the main PCB secured
correctly?
2 Is the polygon motor connector
on the engine PCB 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
between the input connectors.
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?
5 Is the heater harness
connector connected to the
low-voltage power supply PCB
and fixing unit secure?
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.
No Reconnect the connector
securely.
Yes Replace the laser unit.
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.
No Reconnect the connectors
securely.
6-22
Remedy
Remedy
Remedy