Canon MP638 Service Manual page 15

Faulty scanning
*1: Replace the print head only after the print head deep cleaning is performed 2 times, and when the problem persists.
Graphic or text is enlarged on printouts in
the carriage movement direction.
Graphic or text is enlarged on printouts in
the paper feed direction.
No scanning.
Streaks or smears on the scanned image.
<2. LIST OF ERROR DISPLAY / INDICATION>
- The part in the paper path causing the smearing
(1) Confirm that the carriage slit film is free from smearing or
scratches:
- Cleaning of the timing slit film.
(2) Replace the following item(s):
- Timing slit film
- Carriage unit
- Logic board
- Scanner unit (for copying)
(1) Confirm that the LF / EJ slit film is free from smearing or
scratches:
- Cleaning of the LF / EJ slit film..
(2) Replace the following item(s):
- LF / EJ slit film
- LF / EJ timing sensor unit
- Platen unit
- Logic board
- Scanner unit (for copying)
(1) Replace the following item(s):
- Scanner unit
- Logic board
(1) Clean the platen glass and the document pressure sheet.
(2) Confirm the position of the document pressure sheet.
(3) Replace the following item(s):
- Scanner unit
- Document pressure sheet
- Logic board
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