Xerox 8500DN Service Manual - Page 48

Theory of Operation Drum Assembly And Transfix System The Drum Assembly and Transfix Module form the key portion of the printer where imaging takes place. The Drum Assembly and Transfix Module are separate, yet interrelated. This section discusses the Drum. The next section provides more detail on the Transfix Module. In operation, the image is rendered on the rapidly rotating drum. The Preheater heats the media to prepare it for the image transfer process. The heated media is then passed between the Drum (now rotating much more slowly) and the Transfix Roller. The pressure applied by the Transfix Roller transfers the image to the heated media. An encoder disk and sensor on the left end of the Drum monitors the Drum's speed and position. Tranfix Roller Preheater Paper Path Drum Heater Drum s8500-019 The drum heater heats the surface of the Drum to about 60o C (140o F) 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 Drum Heater Relay Board controls the series/parallel operation. The Drum Temperature Sensor 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 Y-Axis Motor drives the Drum. Through a single reduction belt drive, the Y-Axis Motor rotates the Drum at a high speed for imaging and a constant low speed for image transfer. The Y-Axis Belt uses an active tension system to allow the pulley to float while the spring actively adjusts the belt tension. Note The drum rotates in different directions for each process. ■ Transfix CW ■ Maintenance CCW ■ Printing CCW 2-16 Phaser 8400/8500/8550/8560 Color Printer Service Manual