Completely Blank; All Black; White Spots - Canon imageCLASS LBP6780dn Service Manual

5
Troubleshooting > Corrective Actions > Image Defects > White spots

■ Completely blank

F-5-3
No image prints
Cause
1) The laser shutter open/close projection part of
the cartridge is damaged
2) The laser shutter arm and laser shutter are
malfunctioning or damaged
3) Poor developing bias contact with the cartridge Clean the contact if dirty.
4) The high-voltage power supply is defective

■ All black

F-5-4
Image is all black
Cause
1) Poor primary charging bias contact with the
cartridge
2) The primary charging roller is defective
3) The high-voltage power supply is defective
5 Troubleshooting > Corrective Actions > Image Defects > White spots
Solution
Replace the cartridge.
If the laser shutter arm or laser shutter does not
move smoothly or if the part is damaged, replace
any defective parts.
Replace the engine controller unit.
Solution
Clean the contact if dirty.
Replace the cartridge.
Replace the engine controller unit.

■ White spots

F-5-5
White spots appear in image
Cause
1) The transfer roller is deformed or has
deteriorated
2) Poor contact exists between the transfer roller
and its shaft
3) The high-voltage power supply is defective
T-5-3
T-5-4
Solution
Replace the transfer roller.
Clean the contact if dirty.
Replace the engine controller unit.
5-3
T-5-5
5-3