Brother MFC8440D Service Manual page 247

7/13/2019
CHAPTER 6 TROUBLESHOOTING
I-13 Image distortion
Possible cause
Laser unit
installation
Laser scanner
LD emission
failure
Laser scanner
motor rotation
failure
Laser scanner
connection
failure
I-14 Faint print
o t i n r p t e s t u t o t i n r P
rint out test print out test print out test
o t n i r p t e s t u t o t i n r P rint out test print out test print out test
o t n i r p t s e t u t o t n i r P rint out test print out test print out test
o t n i r p t s e t u t o t n i P r rint out test print out test print out test
o t n i r p t e s t u t o t i n P r
rint out test print out test print out test
o t n i r p t s e t u t o t i n r P rint out test print out test print out test
o t i n r p t e s t u t o t i n P r rint out test print out test print out test
o t n i r p t s e t t u o t i n P r rint out test print out test print out test
o t i n r p t s e t u t o t i n P r
rint out test print out test print out test
o t n i r p t e s t t u o t n i r P rint out test print out test print out test
o t n i r p t e s t u t o t i n P r rint out test print out test print out test
o t n i r p t s e t t u o t i n P r rint out test print out test print out test
o t n i r p t s e t u t o t i n P r
rint out test print out test print out test
Possible cause
Machine
installation
Toner cartridge
Scanner window
dirty
Laser unit failure
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Step Check
1 Is the laser unit secured to the
frame incorrectly?
(Check if there is any play.)
2 Is the laser diode or the
scanner motor defective?
3 Is the scanner harness
connected properly?
(Check if it is coming loose.)
Print out test print o
rint out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
Print out test print o
rint out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
Print out test print o
rint out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
rint out test print o Print out test print o
Print out test print o
rint out test print o
Step Check
1 Is the machine placed
horizontally?
2 Does the problem happen
immediately after replacing the
toner cartridge with a new
one?
3 Is the scanner window dirty?
4 Is the problem solved by
replacing the laser unit?
Brother 8840D Service Manual
Result
Yes Secure the unit correctly and
tighten the screws.
Yes Replace the laser unit.
No Connect the harness correctly.
Result
No Place the machine on a flat
surface.
Yes Remove and carefully shake the
toner cartridge horizontally.
Yes Clean the scanner window with a
soft dry cloth.
Yes Replace the laser unit.
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Remedy
Remedy
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