I just recently purchased a used Xerox Phaser 6280 color laser printer, and it has a problem that I was not quite expecting and don't really know what to make of. When printing in color, it prints perfectly straight horizontal lines that repeat at regular intervals. The lines are quite thin; I don't have good tools to measure their width, but by eye they seem to be somewhere between 0.5-1.0 mm, so much more than one "pixel", but still quite thin. They go all the way from the very left edge of the paper to the right edge.
The lines are primarily cyan and yellow, and they repeat at 76 mm intervals, which, if the service manual is anything to go by, matches the drum diameter very well (which it specifies at 75.4 mm). However, I can't really imagine that the drums would be damaged in such a way as to produce perfectly straight lines, and especially not two drums being randomly damaged in the exact same way. Right? I have also inspected the drums by eye, and I can't see any physical defects on them.
Furthermore, the distance between the blue and yellow lines seems to very closely match the distance between the drums as they are mounted in the printer, being 113 mm apart. This leads me to believe that something happens that causes a line on both cartridges at exactly the same time.
While not leaving lines in the same way, the magenta cartridge also seems to show some kind of similar defect. While it doesn't print a line per se, it has some weird kind of "smudge" that is also perfectly straight horizontal. I can't quite describe it, but it looks kind of as if there is one thin band where the toner is rarefied, followed immediately by a similarly thin band where it is laid on somewhat more densely. There is no visible magenta defect in places where there isn't supposed to be any magenta toner, however. These defects do, however, also appear with the exact same interval, and also matching the mounting distance of the drums, so I would assume that they are related somehow.
The black cartridge had the same kind of problem when I first received the printer, however they actually seem to have faded by now, to the extent that I probably wouldn't notice them if I didn't know to look for them. Looking back at the pages I printed that still had the problem, they also seem to obey the same distance relative to the other colors, matching the mounting distances of the drums inside the printer. The width of the lines seems to be exactly identical for cyan, yellow and black.
Like I said, I'm having trouble figuring out any kind of mechanical problem that could cause this, so any help would be greatly appreciated. I don't know if it could be some kind of software issue, but at least the same defects appear whether I'm printing from a computer or using the built-in test prints. As I hinted at earlier, the colored lines only appear when I print in color mode, whereas if I print in black-and-white mode, only the very faint black lines appear. If I print in color made, and there are pages that contain no actual color, they will actually have the colored lines, but they will be extremely faint (like the black lines are).
Thanks for any help!
Solved! Go to Solution.
The problem is really from the drums. It is a known problem for this type of printer when the printer does not work longer. The drums are always in contact with the transfer belt and their charge rollers. That is why it is ideal to work frequently with the printer, and when it is known that it will not be used for a long time or even when transporting the printer, the cartridges should be removed and stored carefully. Try to give more prints to see if the defect disappears, and if not you will need to replace them with new ones.
Interesting, and thanks for that informative reply! Examining it a bit further does seem to confirm that, because manually moving the drums does throw the lines out of the alignment I mentioned, so I guess that does explain it. I'll certainly try printing a bit more and see what happens.
I'm still a bit surprised, though, and I'd like to learn more about the theory behind this if possible, because while this is my first color laser printer, I've had several B/W laser printers in the past, and none of those seem to have had that problem, and yet I'm pretty sure that their drums are also in constant contact with their charge and transfer rollers. And yes, some of them have stood unused for over a year or two without acquiring this problem. Is there anything peculiar to this printer design that causes the problem? Is the belt somehow different from a plain old transfer roller in this regard, or what?
Not that that is something that I'd expect an answer to, but more as a reflection, I'm also rather surprised that I didn't find anything on Google if this is a typical failure mode. I could hardly find any information at all on repeating horizontal lines. The service manual also doesn't seem to cover it in its troubleshooting chapter.
From what I noticed this is happening also in other printers, especially small printers. In some of the large printers, the first transfer rollers have a system that withdraws the transfer rollers