Xerox Phaser 7300B, Service Manual, Page: 247 / 277

Theory of Operation 8-231
Imaging Unit Up/Down Movement
1.
Rotation and up/down operation of the imaging unit are conducted by a single
pulse motor. The main motor rotating counter-clockwise (a) turns lever 1 to the
left. As a result, lever 2, supported by lever 1, moves down, lowering the imaging
unit. With the imaging drum contacts (3-pin) sensing its position, the imaging unit
descends to the lowest position (or printing position) based on a timed-rotation of
the imaging unit motor. There, the drum gear engages with the driving gear and
starts rotating to transfer the image from the imaging unit to the sheet of paper as it
passes by. At this time, when the lever 2 reaches the lowest position, the one-way
gear idles.
2. Rotating the imaging unit main motor in the direction of the arrow (b) causes lever
1 to push up the imaging unit via lever 2. Once the imaging drum contacts are
activated, lever 1 continues to raise the imaging unit creating a gap between the
drum and the transfer unit. At this time, the drum gear does not rotate as it is
separated from the driving gear.
3.
The imaging drum contacts sense “on” when two pins are pushed up by the springs
on the board to touch the conductive plate positioned above them. The imaging
drum contacts sense “off” when two pins are pushed down by the Imaging Unit to
separate the pins from the plate, opening the connection between the pins. The
imaging drum contacts also verify installation of the imaging unit.
S7300-139
Lever 2
Lever 1
One-way
gear
Drum
Driving
gear
I/D unit