Xerox Phaser 8860 Service Manual page 119

Reverse Text
The print indicates if the printhead is producing properly-sized drops of ink and that the drum
temperature is not too high.
NOTE: This print should be made with the system covers closed and in place. The heat loss
without the covers can hide the "too-hot" thermal problem. Also print the test print in Enhanced
print mode.
Look for: Legibility in the lines of 6-point text, particularly in the primary colors. If the letters are
closed or badly "plugged" with ink, the printhead is laying down too much ink. A good-quality
print shows five vertical parallel lines of different thicknesses on the left and right side of the
print. If the thinnest line is missing, the printhead is outputting too much ink or the drum tem-
perature is too high.
NOTE: Ensure that the system is not in High Resolution/Photo or Standard print mode.
Causes: Check the thermal regulation of the printhead and of the drum. Make sure that the
drum temperature sensor is correctly mounted and in proper, even contact with the drum. If
necessary, remove the sensor and check it for an accumulation of debris at its contact point.
Replace the drum temperature sensor. Ensure the Printhead drive voltage is set to the default
128.
Figure 4 Test Print 4 Reverse Text
Big Bands Hand Feed OHP
This print allows you to evaluate transparency printing. It prints two transparencies from Tray 1:
one with primary color fills and one with secondary color fills and a band of 50% blue.
Look for: Scratching on the print. Uniformity of fill with no scratching. Evaluate the print on an
overhead projector. Some print artifacts visible on the print do not show when projected. Like-
wise, some defects do not show until projected.
Causes: Confirm that you are using the transparency that is supported for this system. Clean
or replace the paper release blade.
Initial Issue
Phaser 8860/8860MFP Service Manual
Figure 5 Test Print 5 Big Bands OHP
Grey Fill, Dot Size Uniformity
This print is made up of a 66% black fill. It reveals variations in the ink-drop-spread caused by
thermal variations, Transfix Roller pressure variations, or drum oiling variations.
Look for: There is a large area of differences in the density across the width of the page (a
slight variation is normal). Look for a lighter vertical band, about 1/3 the width of the page, run-
ning the length of the page. Look for small, light spots, or irregular white lines, vertically aligned
with each other, in the print every 125 mm (5.0 in.).
Look for ink on the top and bottom margin of the page, or ink on the back of the page. This pat-
tern is sensitive to the density variations in the paper it is printed on. Use a high-quality grade
of system paper; otherwise, the print appears mottled.
Causes: Use the diagnostics to check the printhead and drum for correct thermal regulation.
Ensure the drum fan is running properly. A vertical band, 1/3 of a page wide, running the length
of the page, is caused by a stuck heating plate in the Preheater. Run the control panel cleaning
procedure Clean Print Smears, which raises the temperature of the Preheater and may free the
stuck heating plate. Additionally, you may manually force a thick sheet of paper (65 to 80 lbs.)
through the paper Preheater to jar the plate free. Light spots that repeat every 11.63 cm (4.58
in.) down the length of the page are caused by a defective Transfix Roller. The roller has a soft
spot that is not pushing the ink into the paper as well as the rest of the roller. If you observe
variations in the glossiness of the print, replace the maintenance kit.
09/2007
3-27
Image Quality