Sharp AR-C150 Service Manual page 56

ADJ 2 Image sub scanning direction distortion
adjustment
1) Make a test chart on A3 (11 × 17") paper as shown below. (Draw
a rectangular with four right angles.)
2) Set the test chart made in procedure 1) on the document table.
(Leave a space of about 30mm between the reference position
and the test chart. With the document cover open, make a copy
on A3 (11 × 17").
3) Check for distortion in the sub scanning direction.
If La = Lb, there is no distortion.
If there is some distortion in the sub scanning direction, perform
the following procedures.
4) Loosen either of two fixing screws of the scanner unit drive pulley.
(Either one on the front or the rear side will do.)
5) With the scanner unit drive shaft kept stationary, turn the scanner
unit drive pulley manually to change the parallelism of scanner
units A and B. (Change the relative positions of the scanner unit
drive pulley and the drive shaft.)
6) Tighten the scanner unit drive pulley fixing screw.
Repeat procedures 2) – 6) until the condition of procedure 3) is
satisfied.
ADJ 3 Image scanning direction distortion
adjustment
1) Make a test chart on A3 (11 × 17") paper as shown below. (Draw
a rectangle with four right angles.)
2) Set the test chart made in procedure 1) on the document table.
With the document cover open, make a copy on A3 (11 × 17").
3) Check for distortion in the main scanning direction.
If the four angles of the rectangle on the copy are right angles,
there is no distortion. (Completion of the adjustment)
If there is some distortion in the main scanning direction, perform
the following procedures
4) Check for a difference between the right distortion and the left dis-
tortion (balance).
Lc
Copy A
Left distortion is equal
to right distortion.
Lc = Ld
If Lc = Ld, there is no difference between the left distortion and the
right distortion.
If the above condition is satisfied, go to procedure 6).
If the above condition is not satisfied, perform the following proce-
dures.
7 – 21
Lc
Copy B
Ld
Ld
Left distortion is not equal
to right distortion
Lc ≠ Ld