Print Engine Calibration; Adjusting For Impulse Banding - Tektronix Z780N - Phaser 780 Color Laser Printer Reference Manual

Print engine calibration

Generally, only one print engine calibration is required. Usually, if you note a
print defect, replacing a toner cartridge, a developer or the imaging unit or
perhaps the paper feeder corrects the problem.

Adjusting for impulse banding

Impulse banding is a print artifact that occurs on prints when the developer roller
comes into contact with the drum. This adjustment adds shims to the carousel
assembly to slightly alter the position of each developer assembly relative to the
drum.
Note The shims used in this adjustment permanently clip into place
and can be difficult to remove. You should modify a set of shims
by cutting the clips off of the shims so they can be inserted and
removed easily. Once you determine the correct shims required,
install permanent shims in their place.
1.
Ensure the printer is in a ready-to-operate condition.
2.
Turn off the printer.
3.
Remove the top cover.
4. With a pen or marker (no pencil), scribe a line across the white tracking
roller located at the front of the developer roller.
5. Position the white roller so the mark is even with the edge of the nearly
developer frame.
6. Hold the carousel lock so it will not impede the carousel's movement.
7. With a slow, smooth action, rotate the carousel assembly 180
allow the carousel to stop as the developer pass the drum surface.
Continue rotating the carousel to bring the marked developer to its
starting position.
8.
As the developer roller contacts and passes the drum surface, the
developer should rotate about 2 mm. Too much rotation, caused by the
roller contacting the drum too soon, causes impulse banding.
Inspect the white tracking roller for movement. If the mark is within
2 mm of its original position, no adjustment is needed.
If the mark is rotated beyond 2 mm, a shim is required.
9. Generally, a 1 mm shim usually corrects impulse banding. Install a
shim in the side of the carousel assembly for the developer being tested.
10. Repeat the procedure from Step 5 until the rotation is about 2 mm. If
rotation is not enough, use a smaller shim. Too much, use a larger shim.
11. Repeat for each developer.
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Phaser 780 Color Printer
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