HP Designjet T2500 eMultifunction Printer series - Manual (Page 222)

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