Canon PC920 Service Manual page 272

c. Adjusting the Mirror Position (optical length between No. 1 mirror and No. 2 mirror)
If you have replaced the scanner drive cable, you must adjust the mirror position, by changing
the position of the cable retainer of the No. 1 mirror mount.
Reference:
1. As more and more copies are made, the cable tends to become slack, requiring adjustment.
2. If the optical length between the No. 1 mirror and the No. 2 mirror is not correct, the horizontal
reproduction ratio will be wrong, causing poor sharpness or blurred images.
1) Fit the mirror positioning tool (FY9-3009) as shown.
2) Remove the copyboard glass. (See Chapter 7.III.C.1. "Removing the Copyboard Glass".)
3) Loosen the screws used to secure the cable retainer at the rear and the front of the No. 1 mirror
mount [1].
COPYRIGHT © 1999 CANON INC.
Figure 11-205
[1]
Figure 11-206
CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 11 TROUBLESHOOTING
11-7