Printhead Drive Voltage Adjustment - Tektronix Phaser 600 Service Manual

Printhead drive voltage adjustment

Printhead-to-media adjustment (tailpiece adjustment)
The voltage used to drive the printhead's piezo-electric crystals is unique to each
printhead. Each printhead's required voltage is printed on the back of each
printhead. Generally, once the voltage is set for a printhead, it is not changed. It
may, in rare cases, be changed as the printhead ages.
In this procedure, you can check and adjust the voltages used to drive the
printhead during printing. The HV+ and HV- voltages should always be equal
but opposite in polarity from each other. Ensure that this is always the case
when you adjust the printhead drive voltages.
1.
Power down the printer.
2. Remove the small access panel on the front of the card cage to access
the power supply test points inside.
3.
Turn on the printer.
4. With a VOM, measure HV+ on Pin 1 (left pin; Pin 2 (center pin) is
ground. Adjust the voltage to the required value listed on the back of
the printhead. Use the left high-voltage adjustment potentiometer
located to the left of the Pin 1 test point.
Measure HV- on Pin 3 (right pin). with a small screwdriver, adjust the
voltage to the required value listed on the back of the printhead. Use
the right high-voltage adjustment potentiometer located to the right of
the Pin 3 test point.
Proceed to the next procedure "Printhead-to-media spacing (tailpiece
adjustment)."
Note All printhead adjustments must be made while the printhead is
warmed up to its operating temperature.
This adjustment is critical for the best print quality. It ensures that the printhead
will always be the correct distance from the loaded media during printing, no
matter the thickness of the media. This adjustment must be correct, for all other
print quality adjustment to be valid.
1. Open the top cover and remove the right cover. Ensure that the
printhead is in its home-position.
2. Manually rotate the head-to-media motor to lower the shim to its
lowest point, inside the head-to-media assembly, on the right end of
the back-tension blade. To ease lowering the shim, pull back on the
back tension blade, moving the blade away from the drum. The shim
should extend 1 mm below the blade. Then back the shim up by
rotating the stepper motor 2 steps.
Checks and Adjustments
Service Manual 9-15
9