Brother mfc8440 Service Manual page 233

CHAPTER 6 TROUBLESHOOTING
M-9 Fixing Unit failure
Possible cause
Poor thermistor
harness contact
Blown thermal
fuse
Thermistor
failure
Halogen heater
lamp failure
Heater harness
connection
failure
NOTE:
•
This problem will be cleared if leaving the printer power ON for ten minutes.
•
If the heater is cooled down sufficiently, this problem may be cleared by enter the
maintenance mode after press 9 key twice. Be warned, however, that this operation
will melt the fixing unit if the heater is hot.
M-10
Possible cause
Main PCB
Software bug
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?
Main PCB failure
Step Check
1 Is it possible to copy?
2 Does this problem appear
when printing specific data or
printing under a specific
environment?
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.
Result
No Replace the main PCB.
Yes Inform the Brother office of
the used specific data,
machine condition and
system environment.
6-26
Remedy
Remedy