Gestetner G060 Service Manual page 151

Rev. 09/2003
Subject
Crow marks When making duplex prints in
low temperature and humidity
conditions, crow marks may
appear on black images,
especially in halftone areas
on the 2
Image density change When the machine is tuned
(1) on in the morning (having
been unused for a while), the
ID of the initial outputs may
be relatively low or high, in
which case the machine
needs to compensate by
raising or lowering the ID
during machine operation.
SM
Symptom
A charge is applied to the paper at each
color station in order to attract each
toner onto the paper. Therefore, the
initial toner colors will receive multiple
charging as they pass each station,
nd
side. which increases the attractive force
between the toner and paper. Since
black is the last toner to be applied, the
attractive force between it and the paper
is lowest. Black toner moves on the
paper during transport to the fusing
section, due to discharge from the toner
to the surrounding guide plates.
When the machine is off, the
environmental conditions can begin to
affect the machine's development
capability. When the main switch is
tuned on, the machine starts a process
control self-check and adjusts the
development parameters to achieve the
proper development potential gap
without adjusting the toner
concentration. Over the course of the
print operation, the ID will then get closer
and closer to the target level.
Cause
Using SP2-301 (Transfer Current), increase the
paper transfer current for black in the mode in
which the problem occurs.
NOTE: White dotted lines may appear on outputs
if the transfer current is increased too much.
Therefore, after adjusting the transfer current, it is
necessary to check the results by making a solid
or halftone image in duplex mode.
If this is often pointed out by users who are very
particular about image density, turn on Auto TD
Adjustment (SP3-125-003) as a solution.
NOTE: It takes about 5 minutes to complete the
self-check.
4-37
TROUBLESHOOTING GUIDE
Action
G060