Theory of Operation 2-11Transfer RollerThe transfer subsystem consists of the Pre-Transfer Lamp (PTL) and the TransferRoller. The PTL exposes the drum surface after the latent image has been developedto 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 depositsit on the surface of the print media.Fuser AssemblyThe Fuser Assembly contains the entire Fuser Subsystem and is a field replaceableService Part. The Fuser Assembly contains the following components:■ Heat Lamp and Heat Roller: a halogen lamp generates the heat for the heatroller. The Heat Roller melts the toner so it adheres to the paper.■ Pressure Roller: provides pressure on the opposite side of the print media sothe heat roller can embed the melted toner in the media.■ Thermistor: monitors the surface temperature of the Heat Roller. Thisinformation is used to control the heat lamp and thus keep the heat roller atthe correct temperature.■ Thermostat: prevents overheat damage when unexpected system faults occur.Paper Feed DriveThe drive for all rollers is provided by the main drive motor and a series of drivegears. When the main motor turns, all the paper path components also turn except thePick-Up Roller. The Pick-Up Roller assembly includes a mechanical clutch, releasedby the paper feed solenoid.Paper Out SensorThe paper supply is monitored by the Paper Out Sensor. When the tray runs out ofpaper, the sensor will send a signal to the Main Board, the control panel LED willblink yellow, and the Paper Out message for the appropriate tray will display on thecontrol panel.
