Print-Quality Troubleshooting 5-19
Random Bands, Lines, Marks, or Missing Spots
There are areas of the image extremely light or are missing entirely and do not appear
to be a repeating defect or in a single color.
Caution
Leaving an Imaging Unit exposed to light for periods in excess of a 10 minutes
can quickly degrade its performance and result in early failure.
Initial Actions
■ Using a flashlight, carefully examine the area around the Imaging Units and
the openings between the Imaging Units and LED Heads. Small
obstructions, such as hair or fibers, can create streaks
■ When troubleshooting, print a test print on at least letter size paper for
diagnosing this problem. The problem may be a repeating defect that is not
noticeable on smaller media.
■ Random missing spots can also be associated with “Cold Offset”, which lifts
toner off the page in certain areas. Usually this will occur in high-coverage
areas where the fuser temperature is not high enough to fuse the toner on the
media. This causes toner to be redeposited further down the page.
Troubleshooting Reference Table
Applicable Parts Example Print
■ Imaging Unit
■ Fuser
■ Transfer Unit
■ Engine Control Board
s7400-327
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