Xerox Phaser 7700 Service Manual page 125

One color is faded or missing
1.
Is the Toner Low Message being displayed on the front panel? Under high
toner-coverage conditions, toner may be depleted during the toner low state
but before the toner out message is displayed.
2. Ensure that the loaded media matches the front panel settings.
3.
Run the Calibrate for Paper routine. From the front panel's Support Menu,
select Improve Print-Quality?, then select Calibrate for Paper Menu.
Note Check the transfer setting before running calibrate paper. If the value is -4, you
need to adjust the transfer settings.
4. Swap the print unit (of the bad color) with the one next to it. (Print units are
not keyed to a particular color.) If the trouble follows the print unit, replace it.
5. Remove the print cartridge and verify that the laser shutter opens and closes
using the Service Diagnostics Shutter Solenoid test.
6. Inspect and test the toner auger system. Ensure that the toner auger motor
operates. Ensure that the toner dispense assembly is carrying toner from the
toner cartridge to the developer.
7. Remove the Accumulator Belt Assembly and inspect the high-voltage knife
connectors on the back side to ensure they are not damaged (RRP 35, on page
7-180).
8.
Replace the Accumulator Belt Assembly.
9. Inspect the high-voltage wiring leading to the Replace the Accumulator Belt
Assembly for damage.
10. Replace the Developer Housing Assembly (RRP 27, on page 7-171).
11.
If the missing or faded primary color appears as speckle on the entire page, the
high-voltage wire leading to that color's developer housing is grounded.
Inspect the high-voltage wiring harness and power supply. Repair/replace as
necessary.
12.
Replace the Laser Unit (RRP 38, on page 7-184).
13. Replace the T3 High-Voltage Power Supply (RRP 44, on page 7-192).
14.
Replace the T2 High-Voltage Power Supply (RRP 48, on page 7-197).
3-102 Phaser 7700 Color Laser Printer
3041-39