Brother mfc8440 Service Manual page 232
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Also See for mfc8440:
- User manual (426 pages) ,
- Software user's manual (183 pages) ,
- Quick setup manual (52 pages)
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M-5
Insufficient output from high-voltage power supply unit
Possible cause
Step
High-voltage
1
contact
High-voltage
2
power supply
PCB
M-6
Fixing heater temperature failure
Possible cause
Step
Poor thermistor
1
harness contact
Blown thermal
2
fuse
Thermistor
3
failure
Halogen heater
4
lamp failure
M-7
Laser Unit failure
Possible cause
Step
Harness
1
connection
failure (1)
Harness
2
connection
failure (2)
Check
Do any of the terminals on the
high-voltage contacts have dirt
or contact burns?
Check the connections of the
connector between the high-
voltage power supply and the
engine PCB are secured
correctly.
Check
Is the contact of connector
CN7 on the engine PCB good?
Remove the fixing unit and
measure the resistance of the
thermal fuse. Is it open circuit?
Is the thermistor installed
properly?
Remove the fixing unit and
measure the resistance of the
halogen heater lamp. Is it
open circuit?
Check
Is the LD harness connector
on the main PCB secured
correctly?
Is the polygon motor connector
on the engine PCB secured
correctly?
6-25
MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
Result
Remedy
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
Remedy
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
Remedy
No
Reconnect the connector
securely.
Yes
Replace the laser unit.
No
Reconnect the connector
securely.
Yes
Replace the laser unit.
SERVICE MANUAL
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