[Misc] Advice needed: Xerox 700 Digital Colour Press- horizontal lines (black only)

[SaxonPrint]

Hello, any advice / suggestions would be much appreciated.

We're experiencing an issue with our Xerox 700 Digital Colour Press whereby when printing lighter greys there is a noticeable horizontal line pattern / banding (perpendicular to the process direction, across the whole print area). The pattern repeats every 1.5/1.75mm and it looks like it has printed on laid paper.

We've used a test file with test strips from 5% to 100% K. The lines are noticeable between 10% and 70%

This issue is only present in K (we've used the same test on CMY)

Scan of the printed test page below.

K test.jpg

The machine has been in use regularly for over a year and this issue has only recently started. We've not noticed any particular environmental change or issue that could explain the problem. The black toner was running low but not empty. We have only recently noticed the issue, but on reviewing some recent print work, we believe the issue has developed within the last couple of thousand prints.

The issue is present regardless of whether we're doing a copy or a job via the RIP (Creo), and presents on all stocks we've tested.

So far we've tried the following steps, with no change to the issue:
-changed the black drum & charge corotron ;
-changed to new black toners;
-put in new black developer housing and new developer;
-opened the back of the machine, checked the drive gears for the developer, cleaned the area. Everything looked ok- we needed to clean some toner off some of the gears, no noticeable missing teeth or gear damage.

We don't believe it is a problem with the ROS as there is no problem with Cyan. (we're aware that there is also a vertical light spot about 1/4 page from the left, this is not the issue we're struggling with)

Many thanks for any advice / suggestions!

[xcopytech]

Re: Advice needed: Xerox 700 Digital Colour Press- horizontal lines (black only)

Clean ROS (laser)

[SaxonPrint]

Re: Advice needed: Xerox 700 Digital Colour Press- horizontal lines (black only)

Clean ROS (laser)

Thanks for this. We thought the ROS would not be the culprit as the Cyan was fine. There was a definite smear pattern on the glass (also on the Cyan's glass). A good clean and the issue has reduced significantly.

For future reference of anyone reading this: We had trouble with error codes related to the ROS cables (). They are very delicate and routing is a right pain. We cleaned the contacts and all worked.

Thanks again, much appreciated!

[Caffeine]

Re: Advice needed: Xerox 700 Digital Colour Press- horizontal lines (black only)

Thanks for this. We thought the ROS would not be the culprit as the Cyan was fine. There was a definite smear pattern on the glass (also on the Cyan's glass). A good clean and the issue has reduced significantly.

Although the K&C are in one unit and the M&Y are in another unit, each color has all its own optics/lenses/mirrors within each unit. So the K could be totally trashed while the C is perfectly fine, even though they are in the same unit.

Actually, they do share a SINGLE component. There is only one spinning polygon mirror per unit, so technically toner dust or whatever on THAT could cause an issue for both colors, but the two lasers hit the spinning mirror at different locations on the mirror, so it is still possible for dirt to affect one color and not the other.

I know you got your situation resolved, so this is more just FYI for anyone else.

I sympathize when it comes to the flat foil cables. They are HORRIBLE. Just getting to the laser units is such a pain. What I would give for them to slide out the side like the older DocuColor 3535/WC 7345 series did... (But, in exchange, we get much easier to access developer units... So I guess it is a wash.)

[SaxonPrint]

Re: Advice needed: Xerox 700 Digital Colour Press- horizontal lines (black only)

Although the K&C are in one unit and the M&Y are in another unit, each color has all its own optics/lenses/mirrors within each unit. So the K could be totally trashed while the C is perfectly fine, even though they are in the same unit.

Actually, they do share a SINGLE component. There is only one spinning polygon mirror per unit, so technically toner dust or whatever on THAT could cause an issue for both colors, but the two lasers hit the spinning mirror at different locations on the mirror, so it is still possible for dirt to affect one color and not the other.

I know you got your situation resolved, so this is more just FYI for anyone else.

Yes, we weren't thinking about the fact that both K&C have quite separate components withing the same unit when first considering the potential issues, therefore wrongly considering the ROS as an unlikely culprit when C was fine. Also, for future reference of anyone finding this thread, we were surprised that streaks on the glass in the ROS unit produced such a clinical repeating pattern which looked much more like a mechanical (slipping, jumping, roller) type issue.

Thanks again to all for the input