HP T2500 Random vertical lines, Wrinkles or folds, Actions, Troubleshooting scan-quality issues

due to incorrect settings, product limitations, or easily solvable mistakes. A failure mode is due to malfunctions of some of the scanner components.

Some of the corrective actions proposed here require the use of the Scanner Diagnostic Plot, which you can print and scan as indicated in The scanner diagnostic plot on page 220. Please do not use any printed version of this guide to test the scanner, as the resolution of the images included here is insufficient. Use the diagnostic plot when recommended in response to any of the errors described in this chapter.

Random vertical lines

This is one of the most common issues in sheet-fed scanners. Usually, the vertical streaks are caused by dust particles inside the scanner, or miscalibration of the scanner (in these cases, the problem can be solved). Here are some examples of images suffering from vertical lines or streaks. Please note the black arrow indicating the scanning direction in these examples.

Actions

1.Clean the scanner’s glass plate and the original to be scanned as described in Clean the scanner’s glass plate on page 157. Re-scan your original afterwards.

2.If the streaks remain, recalibrate the scanner as indicated in Calibrate the scanner on page 165. Make sure you clean the maintenance sheet before calibrating the scanner, and check that the maintenance sheet is not damaged (if so, call HP support and ask for a new maintenance sheet). Re-scan your original after the calibration is completed.

3.If the streaks still remain, check the scanner’s glass plate visually. If it is damaged (scratched or broken), call HP support.

4.If the streaks remain, there may be dust particles inside the glass plate. Carefully take out the glass plate and clean it as described in Replace the scanner’s glass plate on page 160.

NOTE: The problem of vertical streaks cannot always be solved, due to the technological limitations of CIS technology. HP offers HD Scanners with CCD technology for higher quality requirements. If the streaks remain after the corrective actions explained above, then no further action can be taken to improve the image quality, except to buy a more expensive CCD scanner.

Wrinkles or folds

Scanners based on CIS technology have a high optical resolution within their focus plane, at the price of a very limited depth of field. Hence, the images are sharp and detailed when the scanned original is perfectly flat against the glass plate. However, whenever the original contains wrinkles or folds, these defects are clearly visible in the scanned image (as shown in the following example).

202 Chapter 23 Troubleshooting scan-quality issues ENWW