Tektronix Phaser 340 Service Manual page 278

Printers serial numbered B0 xxxxx to BB xxxxx .
Service Test Print 6 - Black vertical lines. This print
is made up of alternating vertical black and white
lines. It reveals variations in the ink drop spread
caused by thermal variations or transfix roller
pressure variations or uneven oiling of the drum.
Look for: 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 1/5
the width of the page, running the length of the page.
Also look for small light spots, vertically aligned with
each other, in the print.
This pattern is sensitive to the density variations in
the paper it is printed on. Use a high-quality grade of
laser printer paper; otherwise, the print will appear
mottled.
Causes: Use the PC diagnostics to check the
printhead and drum for good thermal regulation.
Also check the printhead-to-drum gap. Ensure the
drum fan is running properly. A vertical band, 1/5
page wide, running the length of the page, are
caused by a stuck heating plate in the paper
preheater. Run the front panel cleaning procedure
Clean: Ink Smears which raises the
temperature of the paper preheater and may free the
stuck heating plate. Additionally, you may manually
force a thick sheet of paper (65 to 80#) though the
paper preheater to jar the plate free. Light spots are
caused by a defective transfix roller with a weak, soft
spot that is not pushing the ink into the paper as the
rest of the roller does. In this case, replace the
drum/transfix unit. Replace the drum maintenance
tray; particularly if you observe variations in the
glossiness of the print.
Test Patterns
Light band
Uneven fill Uneven fill
Should see Should see
even fill even fill
left to right left to right
Service Manual
B
9100-88
B-4