Odd+Printer+Artifact

=There is an odd artifact on all my prints that looks like "ghosting"=


 * Problem:** Jim Harrison encountered a strange artifact on all of his prints. The problem is a strange "shadowing" of dark black areas. There appears to be a "ghost" image displaced from the original dark lines. In the jpeg image shown below the left side is the Banding Test file at actual pixels (100%), while the right shows a photo of the print containing the artifact. There is a red line above the branch that shows the "ghost image" directly BELOW this branch:




 * Resolution:** The service tech first tested to be sure that the problem was reproducible from his laptop to eliminate any possibility that it was an issue with my computer or the communications. He connected via USB while I normally connect via Ethernet. These tests showed the same issue was present, so that eliminated pretty much everything associated with the data being sent to the printer and the method of data transfer. Next, the main controller assembly was replaced. This is the "main board" for the unit and must perform all of the intricate calculations determining ink-droplet generation and placement. This, unfortunately did not resolve the issue either. The third step was to swap out the carriage relay PCB assy which seemed like the logical next step. It was clear that the heads would need to be removed in order to do this so we pulled them out. However, once the heads were out it became clear that replacing this board would still require that the carriage be completely removed from the printer and disassembled separately--not a trivial matter.

Since there was nothing to lose and everything to gain, the heads were reinserted. We then printed one of my test grids and it looked even worse than before! In a way, that was encouraging because it showed that the heads don't necessarily go in exactly the same each time. We ran an advanced automatic head alignment and then printed a test grid. Perfect! So we ran a few more tests, and the "ghosting" had been totally eliminated.

The conclusion seems to be that the heads don't necessarily go in exactly the same each time you install them, which is to be expected. In my case, it appears that the way they went in when I first set the machine up had one or both positioned such that the head alignment procedure simply could not accommodate their relative positions. There simply must not have been enough "range" in the alignment system to compensate for the mechanical error that existed. Oddly, before the heads were removed and reinserted, the manual head alignments appeared to be fine when you ran them, yet the result still did not get the alignment of all of the colors with respect to each other to be correct.