Yellow lines iGen4

Getting a problem when we run a job after about 20 sets 2 up, 66 page book 12 x 18 double sided the yellow starts getting lines.
Not evident on the back edge of print but moving towards the front edge the lines get more pronounced. Happens on both sides in process direction.
We can pause the job, let sit for a minute and restart the job and prints beautifully for another 20 sets then it's back.
Have swapped charge screen, Wire mod, donor rolls all to no avail.
Any ideas?

 

Whoa, that's messed up.

Does it occur in yellow halftone too?

CPUC is on? CPUC Lamp is clean?

I've never seen that before. I'm curious to know what it is.

 

It takes so long to show up that we haven't been able to reproduce in FPHT 20 test on about 200 pages. I guess we could waste about a 1000 pages and find out...lol.
It only shows up in the imaging area too, no background at all. 951 sets up no problem. CMT sets up and engine check is 10s for all colors

 

Mmmm - I can't see clearly enough to see whether the lines are digital or xero. As a start check the cleaner is clean and has good vacuum (3.5H2O) and rep the flicker bars. I have seen similar in Magenta when there has been a buildup on the bars.

They look to close together for STAB issues but worth a look

--
Mark

 

Could the CPUC lamp cause this only in Yellow? I would think that it would show up in Magenta first. And the edge of the lines are so crisp and straight, no fuzziness. It does only happen when we have run about 1200 images through. I was thinking it was a charging issue and that does play into the whole charging area
Could it be that I'm running the screening at 200 instead of the standard 175?

 

Check the seam on the PRB to see if there is any build up that is dragging approx 1/2" on the trail edge. Yellow is the colour that is layed down for the CPUC nearest the seam if I remember correctly. There is also a lube bar layed down that is yellow across the seam. You may not see anything unless the engine is running as the cleaner will clean any residue from the seam. Get your engineer to check whilst it is running for any extra toner at the seam by looking at the belt between the transfer and the CPUC

You can disable the CPUC in DC131 (uncheck the screen NVM's in pairs and reboot after) to eliminate any CPUC issues

--
Mark

 

Update*

Talked to a buddy and found out that the Toner concentration is most likely too high for the yellow. Too high TC can cause this especially in yellow where it is more prevelant. I personally have only seen toner spitting come from too high of TC but evidently this is a symptom of that also. Will let you know of the outcome.