Xerox 8500DN Service Manual - Page 45

Drum Maintenance Kit Theory of Operation The Drum Maintenance Kit creates a thin layer of silicone oil on the surface of the Drum prior to printing. The oil keeps the ink from sticking to the Drum's surface and facilitates image transfer to the media. The oil is contained in porous foam rollers made from rolled paper/fiber material. Prior to each print, the Process Motor drives the Drum Maintenance Camshaft to raise the Drum Maintenance Pivot Plate, which raises the oil roller against the rotating Drum. The same camshaft raises a wiper blade to assure that the oil film is smooth and even across the Drum's surface. The Process Drive rotates in one direction. This rotates the Drum Maintenance Camshaft and raises the drum maintenance system to the Drum. The Process Drive then rotates in the opposite direction to lower the drum maintenance system. The blade removes oil and drains it back into the maintenance kit drawer through a felt filter. The oil roller can then reuse the oil. As the Drum completes one rotation, the rotating cam lowers the oil roller and then lowers the blade. The Drum has a floating deadband; the narrow section of the drum containing excess oil and other debris. The oil bar is left on the drum surface when the blade is removed from the drum. This oil bar location is controlled to keep it outside of the print area. An EEPROM chip, built-in to the Drum Maintenance Kit, stores the number of oiling cycles performed and the number of prints remaining to track consumable life. At printer startup, four oiling cycles condition the Drum. Drum Oil on Drum Blade Drum Maintenance Maintenance Roller Camshaft Drum Maintenance Pivot Plate s8500-016 After replacing the Process Drive, Drum Maintenance Pivot Plate or the Drum Maintenance Camshaft (or any component requiring removal of the Process Drive), the printer may experience Front Cover jams from Tray 2. The jam occurs with paper in the Preheater and C3T jam errors (strip flag timeout during transfix) recorded in Jam History. In many cases, Tray 1 (MPT) prints with no jams. These symptoms indicate that the Transfix Load Module is incorrectly timed resulting in a late arrival of the leading edge at the strip flag. The likely cause is the position of the Drum Maintenance Camshaft gear in relation to the Process Drive gear. To correct this problem, see "Timing the Drum Maintenance Camshaft" on page 6-9. Phaser 8400/8500/8550/8560 Color Printer Service Manual 2-13