Ricoh D146 Service Manual page 1235

Main SP Tables - 4
4813 [ALC Selection]
FC
Sets ON/OFF variable correction for scanning level of original when
continuously scanning multiple originals using ADF.
For increasing productivity of ADF, creating correction data is done at a certain
(3min) interval.
If shade correcting data is not updated, original scanning level will change
affected by the light source brightness changing, therefore, variable will be
corrected by scanning the guide plate (white) of ADF from between originals.
001
This SP setting (enable/disable) will apply to color scan.
In an occasion of an unexpected malfunction and level correcting does not
work, or background density disorderly changes among multiple scanned
originals, and by changing setting these will improve; then temporarily set
correction OFF.
By setting interval shading OFF with SP4-351-001, even when ALC is set to
OFF, shading will be done each time, and will prevent density change when
having level correction OFF.
But in this case, shading data is created (moving carriage) with original interval
of ADF scanning, therefore Productivity will drop
D146/D147/D148/D149/D150
[0 or 1 / 1 / 1/step]
*ENG 0:OFF
1:ON(default)
2-516 System Maintenance Section