Xerox Phaser 7750DXF, Service Manual, Page: 55 / 505

Theory of Operation 2-19
#1 Skew (Fine) Setup
The Skew (Fine) Setup is performed to ensure that images on the accumulator belt are
not skewed.
To complete this part of the procedure, a series of chevron images are developed on
the belt, using all four colors. (Pattern 1 on the previous figure shows the chevron
patterns). The chevron patterns are developed on the belt on the front and rear edges
of the accumulator belt. The MOB sensors read them, and the horizontal and vertical
position of the marks are calculated. If the marks are found to be skewed, the
diagnostic tool indicates the number of clicks and direction that the adjustment screws
on the front of the ROS should be turned to correct the skew.
#2 IN/OUT Setup
Like Skew, the IN/OUT Setup procedure uses the chevrons that are developed on the
front and rear edges of the accumulator belt. (Pattern 1 on the previous figures shows
the chevron patterns). During this procedure, logic automatically performs a
magnification adjustment so that the scan lines are the same length for all four colors.
#3 Center Setup
The Center Setup procedure determines if the chevrons developed on the center of the
accumulator belt are in the correct location relative to the front and rear chevrons.
To perform the procedure, the MOB sensor is positioned to the center of the
accumulator belt and the chevrons are developed. (Pattern 1 on the previous figures
shows the chevron patterns).
In this procedure, the midpoints of the scan lines for all four colors are aligned for
magnification balance.
#4 Skew (Rough) Setup
The Skew (Rough) Setup is used only when skew is outside of the measurement
parameters of Skew (Fine) Setup. It should be run in situations when the registration
is so far out of specification as to be immeasurable by the Skew (Fine) Setup routine.
In this routine, Pattern 2 (from the figure showing the chevron patterns) is developed
and the registration of the images is calculated. If necessary, the skew of the image
can be adjusted manually.