Ricoh D131 Service Manual page 638

Dust Detect: On/Off: Rear
Adjusts the sensitivity for dust detection on the ADF scanning glass. This SP is
available only after SP4020-2 is switched on.
[0 to 1/1]

If you see black streaks in copies when no warning has been issued, raise
11
the setting to increase the level of sensitivity.

If warnings are issued when you see no black streaks in copies, lower the
setting.
Dust that triggers a warning could move be removed from the glass by the
originals in the feed path. If the dust is removed by passing originals, this is not
detected and the warning remains on.
12 Detect Level: Rear
Sets the level for vertical line correction (the black vertical lines caused by dust
on the ADF exposure glass).
[0 to 8/1]
0: No vertical line correction.
1-7: Enables and sets the level for vertical line correction. If you select a higher
number, this can decrease the unwanted lines caused by dust. But, it can also
erase thin vertical lines of the original.
Operation Check APS Sensor
Displays the APS sensor output signals when an original is placed on the
4301
exposure glass. If a non-standard size is placed on the glass, asterisks (*) are
displayed.
SM Appendix 3-63
SP4000 Scanner
D131/D132/D133