PRESS C1060 uneven black fill

[blackcat4866]

This was a fun one. My enduser at his print shop has some skills. He had saved for me this test pattern 1 at +125 K. The rear side is a good 10% lighter than the front.

C1060 black fill before.JPG

It help fishing out some of those fibers discharging the grid, but that only smoothed out the gradation. I swapped corona units, no change. Developer has only 7% and the brush looked perfect. The drum had 32% and had no visible flaws.

Our other press tech suggested swapping around primary transfer rollers, and drums. Primary transfer rollers made no change. It was the black drum that was the cause. When swapped to cyan, that's where it went.

C1060 black fill compare.JPG

I had not noticed any issue at installation of those drums, but I suppose I wasn't looking for it. The 11% ARCH B test pattern did not show it. The internal test pattern 1 is the only way I could consistently see it at ~45% fill. I just thought that it was interesting.

Does anybody know what's up with this one drum? It will probably finish it's life as yellow, since defects in yellow are very difficult to identify. =^..^=

[Phil B.]

could the charge be losing charge and gaining it back?

Yeah Brother.. weird one there.