Detailed Explanation - Gestetner B147 Service Manual

Detailed Explanation

The table below shows the troubleshooting procedure for the considerable image problems.
Subject
Symptoms not related to color
Vertical white dotted If the paper transfer bias is
lines excessive for the paper type
used in the low humidity
condition, vertical white
dotted lines may appear.
Vertical white lines In high temperature and
humidity conditions, vertical
white lines may appear in
halftone areas on thick paper
after multiple prints of the
same image.
Dirty lines/bands or
background on 2nd
side
Poor fusing / Fusing
offset
Smeared image When making prints of an
original with a solid image
near the trailing, a smeared
image may appear.
B147/B149/B190
Symptom
In the low humidity condition, the
electrical resistance of paper tends to
increase. Excessive paper transfer bias
may cause electrical leak, causing
vertical white lines.
In this condition, the drum sensitivity
tends to drop. Since the image transfer
efficiency differs between plain and thick
paper, sensitivity drop may cause
changes in image transfer efficiency on
thick paper, causing vertical white lines.
The cleaning blade of the transfer belt
cleaning may be worn away or damaged
when the transfer belt cleaning unit
becomes close to its life (500KP).
The type of paper selected in the printer
driver does not match the paper type
used for printing, causing the fusing
temperature not to be controlled for the
paper used.
The paper's trailing edge tends to flip up
and come very close to the fusing belt
after it passes the paper transfer unit.
The static electricity built up on the
fusing belt may cause toner to move,
resulting in the smeared image.
This is most noticeable with 600x600dpi
printing.
Cause
• Check if the optional heater has been installed
in the paper tray and it is activated.
• Customize (decrease) the paper transfer
current for the related mode (SP2-301).
The drum sensitivity recovers, and this symptom
disappears after waiting for about 5 minutes after
this symptom has been observed.
Check and replace the transfer belt-cleaning unit.
Please instruct users to select the correct paper
type in the printer driver.
Please instruct users to select 1800x600 or
1200x1200dpi
4-61
TROUBLESHOOTING GUIDE
Action
.
SM