Canon MF720 Series, Service Manual, Page: 251 / 327

Trouble shooting items
Recurring faulty image
Foreign matters or lines on rollers along the paper feed path may cause faulty images in the vertical scanning direction.
Field action
See the roller pitches listed in the tables below to clean and/or replace the corresponding parts.
Roller pitch Parts
about 44 mm Registration roller
about 58 mm Secondary transfer external roller
about 75 mm Photosensitive drum
about 22 mm Developing cylinder
about 58 mm Fixing film
about 63 mm Pressure roller
about 713 mm ITB (drive roller, secondary transfer internal roller)
Confirming nip width
This product does not provide the function to adjust nip width. Improper nip width, however, may cause faulty fixing.
To avoid potential faults, confirm the nip width of the fixing assembly in the following steps.
1. Output a A4 sheet printed in solid black using the cartridges for this product and bring it to the customer site.
2. Set the solid black sheet face-down to the cassette of this product.
3. Use an external device to print out a solid white image on the sheet.
4. Open the front door after about 25 seconds from the step above and leave it for 10 seconds or more in the device to take
out the printed sheet.
5. Measure the glossy part on the printed sheet as shown in the figure below to confirm if the width is in the tolerable ranges.
• Center (a): 6.0+-1mm
• Sides (b), (c): 5.0-7.5mm
• Difference (b-c): 1.0mm or less
b
c
Paper feed direction
Center of
A4 sheet
a
6. Troubleshooting
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