Image Defects; Ii. Image Defects - Canon LBP-1760 Service Manual

CHAPTER 4

II. IMAGE DEFECTS

If the factor of the malfunction is identified as "image defect" by the malfunction diagnosis flow-
chart (Figure 4-1-1), find out the defective phenomenon and clear it according to the table shown
below.
• I-1 Light:
• I-2 Dark:
• I-3 Completely Blank:
• I-4 All Black:
• I-5 Dots in Vertical Lines :
• I-6 Dirt on Back of Paper:
• I-7 Vertical Lines:
• I-8 Black Horizontal Lines:
• I-9 Dirt:
• I-10 Blank Spots:
• I-11 White Vertical Lines:
• I-12 White Horizontal Lines:
• I-13 Poor Fixing:
• I-14 Image Distortion:
• I-15 Sharp Black Horizontal Lines:
I-1. Light
<Possible causes>
1. The image density is not adjusted correctly.
Action: Adjust the image density by operating the external device.
2. Open the top cover and remove the EP-52 cartridge while printing. Open the drum protec-
tive shield of the cartridge and check the toner image on the photosensitive drum surface.
If the toner image has not been transferred to the paper properly, go to step 3). If the toner
image on the drum is faint, go to step 6).
Do not open the drum protective shield for more than 10 seconds.
3. Deformation or deterioration of the transfer charging roller
Action: Replace the transfer charging roller.
4. Poor contact between the engine controller PCB transfer charging roller and its shaft
Action: Clean the contacts if dirty. If the problem still remains after cleaning, or parts are
deformed or damaged, replace them.
5. Defective engine controller PCB
Action: Replace the engine controller PCB.
6. Defective laser/scanner unit
Action: Replace the laser/scanner unit.
7. Defective engine controller PCB
Action: Replace the engine controller PCB.
4 - 10
Table 4-2-1
Output very light image
Output very dark image
Output no image
Output all black paper
Output white dots on the paper
Output dirt on the back of the paper
Output vertical lines on the paper
Output horizontal lines on the paper
Output dirt on surface of the paper
Output image with blank spots
Output white vertical lines on the paper
Output white horizontal lines on the paper
Output the image with poorly fixed toner
Output distorted image
Output sharp black horizontal lines