Tektronix Phaser 840, Service Manual

Page: 119 / 207

108 Phaser 840 and 850 Color Printers
Drum position encoder gap
This procedure ensures that the drum-position sensor assembly’s encoder wheel
rotates freely inside the gap of the drum-position sensor without the encoder
wheel’s disk touching the sensor. If the disk touches the sensor, it can abrade the
disk and result in erroneous drum position readings.
Note
Do not rotate the encoder will on the drum shaft. Altering the
position of the encoder wheel relative to the drum shaft will alter
the location that the stripper fingers (Phaser 840 printer) or rapid
release guide (Phaser 850 printer) contact the drum. Any marks
on the drum left by the stripper finger or rapid release guide in
their original position would then appear in the printed area of the
drum.
With a marker pen, draw an alignment mark on the shaft end and
the encoder wheel to help ensure their positions to each other do
not change.
1. Phaser 840 printer only: Ensure that the retaining spring is not in the
drum-position sensor assembly’s encoder wheel groove. This ensures
that the encoder wheel is not tensioned and slides easily onto the drum
shaft.
2. If not already mounted in place, secure the drum-position sensor
assembly onto the drum shaft and secure it to the printer frame.
3. Through the access hole in the drum-position sensor assembly, position
the encoder gap tool on the drum shaft.
4. Reposition the drum-position sensor assembly’s encoder wheel on the
drum shaft until it butts firmly against the encoder gap tool.
5. Phaser 840 printer only: Holding the gap tool in place, with a small,
flatblade screwdriver, slide the encoder wheel’s retaining spring into
the encoder wheel’s groove.
6. Remove the gap tool. Reassemble the printer and make a test print.