Sharp MX-C250 Service Manual page 50

5-B Print engine image skew (LSU skew)
adjustment (Manual adjustment)
(No need to adjust normally)
If a more accurate adjustment than the automatic adjustment ADJ
5A is required, use this method of adjustment.
This adjustment is made by changing the parallelism of the LSU
unit scan laser beams for the OPC drum.
1) Enter the SIM 50-20 or 64-01 mode.
2) Select the paper feed tray with A4(11"x8.5") paper in it, and
press [START] key.
3) The image skew (image registration) adjustment pattern is
printed.
4) Check the printed black image for any skew.
Use the four cross points printed in black to measure the
squareness.
There are following two methods of checking the black image
for any skew (right angle).
Method 1
Measure the distances between opposing corners of the rect-
angle print pattern, and compare the two distances to check
the squareness.
Method 2
Check the squareness of the vertical and horizontal sides of
the rectangle print pattern by using A4(11"x8.5") paper sides.
In the case of Method 2, the right angle of paper to be used
may not be exact. Be sure to check the right angle of paper to
be used in advance.
Method 1
Measure the length of the diagonal lines of the rectangle print
pattern.
Calculate the difference between the measured lengths C and
D of the diagonal lines.
Check to insure that the difference between C and D is in the
following range.
C - D = 0.8mm
If the difference between C and D is in the above range, there
is no need to adjust.
Method 2
Fit the side of A4(11"x8.5") paper to the long side of the rectan-
gle print pattern.
Measure the slant (skew) of the vertical side for the horizontal
side of paper as shown in the figure.
If the above distance is 0.5mm or less, there is no need to
adjust.
If the above condition is not satisfied, perform the following
procedure.
5) Open the front cover, remove the waste toner box, and turn the
four LSU image skew adjustment screws in the same direction
by the same amount.
For the adjustment, remove the front cover and the waste
toner box, and turn the skew adjustment screw.
(Skew adjustment screw rotation direction)
When C is greater than D in the method 1 or there is some
skew in the direction A in the method 2, turn the screw clock-
wise.
When C is smaller than D in the method 1 or there is some
skew in the direction B in the method 2, turn the screw coun-
terclockwise.
(Reference of the rotation amount of the skew adjustment
screw)
In case of the method 1, 0.8mm/about 1.5 rotations
In case of the method 2, 0.5mm/about 1.5 rotations
Repeat the procedures 2) to 6).
After completion of the black image skew adjustment, go to the
procedure 7).
6) Perform the same procedures as 1) and 2).
7) Check the printed color image for any skew.
If the difference between the shift amounts on the F and R
sides is within +/- 1 scale of the fine adjustment check scale,
there is no need to perform the adjustment.
Measure the skew amount from the print patterns on the front
and rear sides of each color.
MX-C250 ADJUSTMENTS 5 – 16
M C
Y