Hitachi HT-4139-28 Maintenance Manual page 48

When "NG" is displayed, check below.
(1) The sheet is normal? (Not extended or shrunk?)
(2) The rollers are not contaminated?
(3) If the Pinch Roller is contacting partially?
(4) Roller wear of the sheet separation mechanism?
However "NG" is displayed, if AVR value is within STD, judge it is OK.
Fig.2 Position of recognition
(4) Display results after scanning specified number of
sheets.
(5) Click the "Confirmed" button.
(6) Return to the dialog (1), and click the Display of
calibration information button.
REV0 2010.02.15
-H7-15-