Xerox Phaser 8860 Service Manual page 310

In operation, the image to be printed is formmed on the rotating drum. The Preheater heats the
media to prepare it for image transfer. The heated media is then passed between the Drum
(now rotating much more slowly) and the Transfix Roller. Under the pressure between the
Drum and the Transfix Roller, the image is transferred. An encoder disk and sensor on the left
end of the Drum monitors the Drum's speed and position.
Figure 16 Drum Assembly
The drum heater heats the surface of the Drum for imaging. The drum heater does not rotate.
The heater is inside the drum, and is controlled by the Drum Heater Relay Board. The drum
heater consists of two resistive heater coils that operate in series for 220 V and in parallel for
110 V operation. The series/parallel operation is controlled by the Drum Heater Relay Board. A
temperature sensor in contact with the drum surface monitors the drum temperature. The main
board interprets the sensor's signal and turns on the drum heater and Drum Fan to heat the
drum, or turns on the Drum Fan alone to cool the drum.
The Drum is driven by the Y-Axis Motor through a single reduction belt drive, the motor rotates
the Drum at a high speed for imaging and a constant low speed for image transfer. The Y-Axis
assembly uses an active tension system to allow the pulley to float while the spring adjusts the
tension.
Theory of Operation
Image Output Terminal
NOTE: The Drum rotates CW for Transfix, CCW for Maintenance and Printing.
Figure 17 Drum Assembly Components
Keep your fingers away from the Drum drive; it uses a closed-loop servo drive system.
Since the motor speeds up if it senses the Drum slowing down, fingers caught in the
belts and gears can be severely injured.
Transfix System
The Transfix Roller, Figure 18, applies pressure to the back side of the media as it moves
between the Transfix Roller and Drum. This pressure transfers the image from the Drum to the
media. A set of springs in the Transfix Load Module, acting through the Transfix Load Arms,
evenly apply pressure across the Transfix Roller as it rests against the Drum. The pressure
must be uniform across the length of the Transfix Roller to avoid paper wrinkles and light spots
on the prints.
After the Transfix Roller is engaged, the Drum rotates to advance the media during the transfix
process. The Drum continues to advance the media until the Transfix Roller is disengaged. The
Transfix Roller is lifted and lowered by the action of the Process Drive. All gears move to rotate
the Transfix Camshaft to bring the Transfix Roller into contact with the Drum. The gears reverse
to rotate the Transfix Roller back to its original position, except when printing from Tray 1 or on
envelopes. The transfix load springs and double lever arms increase the force when the cam-
shaft is engaged.
09/2007
8-18
WARNING
Phaser 8860/8860MFP Service Manual
Initial Issue