2-16 Phaser 8400 Color PrinterDrum AssemblyThe drum assembly and transfix system form the key portion of the printer whereimaging takes place. The drum assembly and transfix system are separate, yetinterrelated. This section discusses the drum assembly. The next section goes intomore detail on the transfix system.In operation, the image to be printed on paper is first “printed” on the rapidly rotatingdrum. The paper preheater heats a sheet of paper or transparency film to prepare it forthe image transfer process. The heated paper is then passed between the drum (nowrotating much more slowly) and the transfix roller. Under the pressure between thedrum and the transfix roller, the image is transferred to the sheet of paper. An encoderdisk and sensor on the left end of the drum monitors the drum’s speed and position.The drum heater heats the surface of the drum to about 60 o C (140o F) for imaging.The drum heater does not rotate. The heater is inside the drum, and is controlled bythe drum heater relay board. The drum heater consists of two resistive heater coils thatoperate in series for 220 V and in parallel for 110 V operation. The series/paralleloperation is controlled by the drum heater relay board. A temperature sensor incontact with the drum surface monitors the drum temperature. The main boardinterprets the sensor’s signal and turns on the drum heater and drum fan to heat thedrum, or turns on the drum fan alone to cool the drum.Paper preheaterTranfix rollerPaper pathDrumDrum heaters8400-118
