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Phaser 8400/8500/8550/8560 Color Printer Service Manual 2-13
Theory of Operation
Drum Maintenance Kit
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.
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.
s8500-016
Drum
Maintenance Roller
Drum Maintenance Pivot Plate
Drum Maintenance
Camshaft
Blade
Oil on Drum