Transfer Roller; Fuser Assembly; Paper Feed Drive; Paper Out Sensor - Xerox 3450B - Phaser B/W Laser Printer Service Manual

Transfer Roller

The transfer subsystem consists of the Pre-Transfer Lamp (PTL) and the Transfer
Roller. The PTL exposes the drum surface after the latent image has been developed
to lower surface potential of the drum. This provides enhanced transfer efficiency.
The transfer roller provides a high positive potential on the back of the print media.
This potential attracts the negatively charged toner image from the drum and deposits
it on the surface of the print media.

Fuser Assembly

The Fuser Assembly contains the entire Fuser Subsystem and is a field replaceable
Service Part. The Fuser Assembly contains the following components:
■
Heat Lamp and Heat Roller: a halogen lamp generates the heat for the heat
roller. The Heat Roller melts the toner so it adheres to the paper.
■
Pressure Roller: provides pressure on the opposite side of the print media so
the heat roller can embed the melted toner in the media.
■
Thermistor: monitors the surface temperature of the Heat Roller. This
information is used to control the heat lamp and thus keep the heat roller at
the correct temperature.
■
Thermostat: prevents overheat damage when unexpected system faults occur.

Paper Feed Drive

The drive for all rollers is provided by the main drive motor and a series of drive
gears. When the main motor turns, all the paper path components also turn except the
Pick-Up Roller. The Pick-Up Roller assembly includes a mechanical clutch, released
by the paper feed solenoid.

Paper Out Sensor

The paper supply is monitored by the Paper Out Sensor. When the tray runs out of
paper, the sensor will send a signal to the Main Board, the control panel LED will
blink yellow, and the Paper Out message for the appropriate tray will display on the
control panel.
Theory of Operation 2-11