Canon LBP-1120 Service Manual page 84

CHAPTER 4
II-2. Dark
<Possible Causes>
1. Improperly adjusted image density.
Action: Adjust the image density by operating the external device.
2. Poor contact in the drum grounding contact on the engine controller PCB and cartridge contact.
Action: Clean the contacts if dirty. If the problem still remains after cleaning, or parts are deformed or
damaged, replace them.
3. Poor contact in the primary high voltage contact on the engine controller PCB and cartridge contact.
Action: Clean the contacts if dirty. If the problem still remains after cleaning, or parts are deformed or
damaged, replace them.
4. Defective laser/scanner unit.
Action: Replace the laser/scanner unit.
5. Defective engine controller PCB.
Action: Replace the engine controller PCB.
II-3. Completely Blank
<Possible Causes>
1. Damaged laser shutter open/close projection of the cartridge cover.
Action: Replace the cartridge cover.
2. Poor contact in the developing bias contact on the engine controller PCB and cartridge contact.
Action: Clean the contacts if dirty. If the problem still remains after cleaning, or parts are deformed or
damaged, replace them.
3. Defective engine controller PCB.
Action: Replace the engine controller PCB.
II-4. All Black
<Possible Causes>
1. Poor contact in the primary high voltage contact on the engine controller PCB and cartridge contact.
Action: Clean the contacts if dirty. If the problem still remains after cleaning, or parts are deformed or
damaged, replace them.
2. Defective primary charging roller.
Action: Replace the cartridge.
3. Defective engine controller PCB.
Action: Replace the engine controller PCB.
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