Aligning the Document Reader Tray
Proper cable placement is important for accurate alignment of the device. Place the cable in the wire channel if the scanner will remain in the base most of the time. If you plan to frequently lift out the scanner to scan items, then set the cable in the location where it will rest while the scanner is in the stand.
Note: The 4850DR will not capture any images until it has been properly aligned using the following procedure.
1.Loosen the screw in the base tray with a coin.
2.Place the alignment page on the tray. Align the upper left corner of the alignment page to the upper left corner of the tray.
3.Make sure the serial number on the alignment page matches the serial number on your document reader.
4850DR serial number 
4.Press the button on the scanner to display the illuminated aimer crosshairs. You will hear a single beep that indicates you are using the correct page.
(If you hear an error razz and the aimer turns off, then you have the wrong alignment page for your document reader.)
5.Move the tray until the illuminated aimer crosshairs line up with the printed crosshairs on the alignment page. (Be sure to wait until the crosshairs go off before removing power or attempting to capture an image.)