White Portion Of Print Is Colored; Color Is Uneven - Tektronix Phaser 440 Service Manual

6
Troubleshooting
6-14 Phaser 440 Color Printer
5. Check the transfer roll take-up motor by measuring the resistance of
its winding. Refer to Table 6-1 for the expected winding resistance
value. If the resistance is incorrect, replace the motor as explained in
the Section 8 topic "Transfer roll take-up motor" on page 8-28. During
printing, the motor keeps the transfer roll at a specific tension as the
transfer roll is pulled passed the thermal head by the motion of the
drum. If the tension is incorrect, print aberrations across the width of
the print can occur.
6. If no problems are found in the previous steps, then you can assume
that the print engine control board is driving the drum motor
incorrectly; replace the engine control board. Refer to the Section 8
replacement procedure "Engine control board" on page 8-40.

White portion of print is colored

1.
If the thermal head is transferring dye to the paper when it shouldn't,
the thermal head is too hot. Thermal head voltage control may be bad;
check the power supply thermal head voltage. Measure the power
being supplied to the thermal head (refer to the earlier topic
"Verifying power supply operation" on page 6-3).
2. Replace the print engine control board. Refer to the Chapter 8 topic
"Engine control board" on page 8-40.

Color is uneven

1.
The paper may be slipping in the drum's paper clamp. Clean the
paper clamp. See Chapter 7.
2. Check the drum's paper-clamping pressure; if it's too low the media
could be slipping. If the clamp springs are weak and cannot firmly
hold a sheet of media, replace the drum. Refer to the Chapter 8 topic
"Drum" on page 8-20.
3.
Check the drum for side-to-side play; there should be none. If the
drum does move from side to side, remove the drum and add a drum
shim washer. The shim washers are included in the hardware parts
kit. Refer to the Chapter 8 topic "Drum" on page 8-20.
4. Check the drum drive belt for proper tension. Refer to the Chapter 9
topic "Adjusting for best print quality" on page 9-16.
5.
Ensure that the drum pulley is correctly mounted on the drum shaft.
The set screws should be driven against the flat cutouts in the drum
shaft. Ensure that one of the set screws fits into a countersunk recess
in its flat cutout. Refer to the Section 8 topic "Drum" on page 8-20