Unsharp Printing; Grey Background - Kyocera Mita FS-6750 Service Manual

Unsharp printing

Check point
Check paper for property.
Check the transfer roller
installation.
Check the transfer bias
potential.
Check EcoPrint setting.

Grey background

Check point
Check the print density set-
ting.
Check the surface potential of
the drum (in the drum unit).
Check the grid.
The developing roller (in the
developer) may be defective.
Suggested remedy
• Paper with rugged surface or dump tends to cause
unsharp printing. Replace paper with the one that satis-
fies the paper specifications.
• The transfer roller must be supported by the bushes at
the both ends. Clean the bush to remove oil and debris.
Replace the transfer roller if necessary.
• Check the transfer bias output on the high voltage unit.
This requires removal of the left cover and the test equip-
ment. Replace the high voltage unit if high voltage poten-
tial is not available on the board.
• The EcoPrint mode can provides faint, unsharp printing
because it acts to conserve toner for draft printing pur-
pose. For normal printing, turn the EcoPrint mode off by
using the operator panel. For details refer to the printer's
User's Manual.
Suggested remedy
• The print density may be set too high. Try adjusting the
print density using the Remote operation panel utility.
For details refer to the printer's User's Manual.
• The drum potential should be appoximately 430±15 V.
This may vary depending on production lots. Measure-
ment is possible only by using the jig and tool specifically
designed for this purpose. The drum unit will have to be
replaced if it bears values far out of the allowable range.
• Clean the grid by grid cleaner.
• If a developer which is known to work normally is avail-
able for check, replace the current developer in the
printer with the normal one. If the symptom disappears,
replace the developer with a new one.
6-24
Troubleshooting
Print quality problems
FS-6750