HP T2500 manual Horizontal periodical banding, Defocus, blurring and fading colors

3.If the problem persists, analyze pattern 4 of the diagnostic plot. If you see the problem shown on the right, call HP support and report a “vibration problem”.

Horizontal periodical banding

This problem can be found in scanners with a defective pressure roll in some CIS modules. In this case, you may sometimes find horizontal periodical bands in your scanned images, separated by around 5 cm (2 in), in the area covered by one CIS module, as in this example: original on the left, scanned image on the right. Please note the black arrow indicating the scanning direction in this example.

Actions

1.Open the scanner lid. Clean the motor wheels (small black rubber) and the pressure rolls (wide white plastic). Check that all the pressure rolls can move freely. If you find dust particles or objects that obstruct the movement of the rollers, try to remove them, then close the scanner lid and repeat your scan.

2.If the problem persists, clean and calibrate the scanner as indicated in Scanner maintenance

on page 156, and analyze pattern 1 of the diagnostic plot. If you can find horizontal periodical banding inside this pattern, as shown on the right below, call HP support and report “horizontal periodical banding”. Please note the black arrow indicating the scanning direction in this example.

Original Pattern 1 affected by horizontal periodical banding

Defocus, blurring and fading colors

CIS technology scanners are tuned to work at a fixed focal distance, and they are very sensitive to small variations in the position of the original with respect to the scanner glass plate. If the scanner lid is not properly closed, or if the original has deep wrinkles or texture, you may sometimes find problems as in the following example (on the right), where the scanned image is blurred and colors are faded.

212 Chapter 23 Troubleshooting scan-quality issues ENWW