Brother HL-5240 Service Manual page 149

(8) Fuser unit failure
Possible cause Step
Poor thermistor 1
harness contact
2
Thermistor 3
assembling
failure
Halogen heater 4
lamp failure
Heater harness 5
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 following steps; 1)
Check that the front cover is open. 2) Turn on the printer power switch while pressing the
Go button. Be warned, however, that this operation will melt the fuser unit if the
heater is hot.
(9) Main PCB failure
Possible cause Step
Main PCB 1
Software bug 2
Check
Is the contact of connector
CN1 and CN2 on the relay rear
PCB good?
Is the contact of connector
CN3 on the main PCB good?
Is the thermistor installed
properly?
Remove the fuser unit and
measure the resistance of the
halogen heater lamp. Is it
open circuit?
Is the heater harness
connector connected to the
low-voltage power supply PCB
and fuser unit secure?
Check
Is it possible to print the test
page with the method of
Sample Page' in Chapter
Does this problem appear
when printing specific data or
printing under a specific
environment?
4-35
HL-5240/5250DN/5270DN/5280DW SERVICE MANUAL
Result
No Reconnect the connector.
No Reconnect the connector.
Yes Replace the fuser unit.
No Reinstall the thermistor
properly.
Yes Replace the fuser unit.
No Reconnect the connectors
securely.
Result
No Replace the main PCB.
'Test
7?
Yes Inform the Brother office of
the used specific data, printer
condition and system
environment.
Remedy
Remedy
Confidential