Uknown problem horizontal stripes

[internetfab]

Since we have a black and white (grayscale) order we continue having the following problem;

The print is perfect but on the paper there is printed also light horizontal stripes (see the photo as attachment). We replaced the CF PHOTOCONDUCTOR 3 UNIT for the color black (part number; DU-101), advised by Konica Minolta Netherland. But the problem stays. On the attachment the stripes are visible in the lower sheet, a clean non-printed sheet is visible above.foto(1).JPG

The problem is only when printing pure black and not on other colors. The pattern is always the same. We checked most of the visible rollers but could find anything.

Does anyone now the solution for this problem?

[internetfab]

The machine is a C500 bizhub PRO

Since we have a black and white (grayscale) order we continue having the following problem;

The print is perfect but on the paper there is printed also light horizontal stripes (see the photo as attachment). We replaced the CF PHOTOCONDUCTOR 3 UNIT for the color black (part number; DU-101), advised by Konica Minolta Netherland. But the problem stays. On the attachment the stripes are visible in the lower sheet, a clean non-printed sheet is visible above.[ATTACH=CONFIG]9502[/ATTACH]

The problem is only when printing pure black and not on other colors. The pattern is always the same. We checked most of the visible rollers but could find anything.

Does anyone now the solution for this problem?