Tektronix PHASER 840 Quick Reference Manual page 144

2: Weak/missing jet. This print shows
which jets are not outputting enough, if
any, ink compared to its neighboring jets.
Note that the yellow jets' bands have a
small amount of cyan ink added to them,
which tints them green, to make them
more visible.
Look for: No interlacing is used in this
print; expect light/dark variation between
jets. Look for much lighter colored vertical
bands in the horizontal bars. Weak jets in
the yellow band are distinguished by a
cyan tint.
Causes: A jet may be partially clogged;
perform printhead clean/purge cycles on
the printhead to remove contaminants
from the poor performing jet. Test the
vacuum system of the cap/wipe/purge
system. Turn the printer off for 4 to 6
hours (or overnight, if practical). Then
perform clean/purge cycle again. As a
last resort, replace the printhead.
3: Color Bands, RGBK Dither - The
large, secondary colored areas in this
print reveal banding and weak jets.
Look for: Vertical "bars" or bands of
much lighter color or a different hue
running in-line in one or more of the solid
fills.
Causes: Banding is caused by
color-to-color misregistration inherent in
the fabrication of the jet. Ensure the
printhead-to-drum spacing is correct.
Then use the PC diagnostics to ensure
that the printhead and drum thermals are
correct. A weak jet can also cause
banding; refer to the Weak/missing Jets
test print. 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. As a last resort, replace the
printhead.
134 Phaser 840 Color Printer
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Weak jet
9923-114
Banding
9923-115