Canon LBP-1000 Service Manual page 129

II-2. Dark
<Possible causes>
1. The image density is not adjusted correctly.
Action: Adjust the image density by operating the external device.
2. Poor contact in the drum grounding contact pin of the drive unit and in the cartridge con-
tact.
Action: Clean the contacts if dirty. If the problem remains after cleaning, or parts (contact
pin, etc) are deformed or damaged, replace it.
3. Poor contact in the primary bias contact on the engine controller PCB and in the cartridge
contact.
Action: Clean the contacts if dirty. If the problem remains after cleaning, or parts are
deformed or damaged, replace it.
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 EP-32 cartridge
Action: Replace the cartridge.
2. Laser shutter is malfunctioning or damaged.
Action: If the laser shutter is not moving smoothly or damaged, replace the laser/scanner
unit.
3. Poor contact in the developing bias contact on the engine controller PCB and in the cartridge
contact.
Action: Clean the contacts if dirty. If the problem remains after cleaning, or parts are
deformed or damaged, replace them.
4. Defective intermediate PCB
Action: Replace the intermediate PCB.
5. Defective engine controller PCB
Action: Replace the engine controller PCB.
II-4. All black
<Possible causes>
1. Poor contact in the primary bias contact on the engine controller PCB and in the cartridge
contact.
Action: Clean the contacts if dirty. If the problem remains after cleaning, or parts are
deformed or damaged, replace them.
2. Defective primary charging roller
CHAPTER 4
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