Background Fogging - Toshiba FC-22 Manual

(4) Background Fogging

Cause/Defect area
Density reproduction
Printer
Parameter adjustment
value
Scanner stain
Auto-toner
Main charger output
Developer bias
Developer unit
Developer material
Drum cleaning blade
Toner dusting
Note:
If the main charger and developer bias outputs seem to be abnormal, replace the main high-voltage transformer of the color likely
to be abnormal with another transformer of another color likely to be normal, and then, output the chart again.
If the same color remains abnormal, check if there is any disconnection of harness between the LGC board and the main high-
voltage transformer, disconnection of high-voltage harness, the power supply defect, or stain on the main charger wire.
If the color changes as the result of replacing the main high-voltage transformer, this fogging trouble is caused by the main high-
voltage transformer defect. Therefore, replace the main high-voltage transformer of the abnormal color with new one.
After this checking, return the other main high-voltage transformer back to the original color position.
FC-22 TROUBLESHOOTING
Step Check items
1 Image density reproduction defect
2 Check printer image.
3 Check image processing parameters.
4 Adjust image processing
parameters.
5 Is the original glass or mirrors
or lens filter dirty?
6 Is the auto-toner sensor normal?
7 Is the toner supply operating constantly?
8 Is the main charger output normal?
9 Is the developer bias proper?
10 Is the contact between the drum
and developer material right?
11 Is the developer's life finished?
12 Is it cleaned properly?
13 Is toner accumulated on the seals of
the developer unit?
Measures
Perform automatic adjustment of
gamma correction.
Output test print image (04-231) for
each color and check it.
Check the value of offset amount of
processing background.
While checking the above encircled
image, remove background fog by
adjusting offset amount of processing
background.
Clean them.
Check operation of auto-toner sensor
and re-adjust.
Inspect motor and circuits.
Check circuits. (Note)
Check circuits. (Note)
Adjust doctor-to-sleeve gap and pole
position.
Replace developer material.
Inspect drum cleaning blade pressure.
Remove toner and clean.
4 - 60
Remarks
Go to step 5
If defects
occur.
January 2000 © TOSHIBA TEC