bad prints on my colorspan 5465Uv noe HP45500

[dasigndr]

I recently changed 4 heads on my HP45500 printer because we were getting bad results. (( getting intermitent printing...like leopard stripes in the consistency of the colours )) Did a "prime Bar" and all the heads are good but I still get the "blotchy striped" printing. Any idea what would cause this??

We removed and cleaned our "Vacuum Manifold" last year because of other issues and we would constantly get an attention warning saying the vacuum pressure is not resetting, etc...But it still would print nice. I am just wondering if this would have something to do with this.
My theory is...Like a paint spray can...the nozzle works fine..but maybe the pressure (hence, the vacuum manifold) acts up and then you get blotchy spraying...
Help me out here!!!

 

[justntym]

Carriage Movement OK?

Quick question. How smooth does your carriage run? I have 2 HP35500 UV printers and was having problems with declining print quality. I would get strange variations in solid colors, etc. I noticed the carriage was running a little rough and checked the bearings. The lower bearing was completely shot and the upper bearings were running rough. This caused the carriage to vibrate a lot which was creating the decline in print quality.

I have replaced the bearings on both machines and they are now quiet and print quality is back and the carriage runs smooth and quiet.

 

[justntym]

Vacuum Recovery

Also, for the vacuum recovery issue, I have had this happen to me and tech support gave me a lot of things to check. I checked all the lines for kinks, holes, bad connections etc. but to no avail.

I found the problem within the vacuum pump. There is a small brass connector in-line that helps regulate the vacuum pressure. Prior to 2010, Colorspan did not put an air filter on this line so it can get plugged. When that happens, the vacuum recovery time takes longer. A good way to tell if this connector is plugged is if the you don't hear the vacuum pump "oinking" on it's regular cycle (you know what I mean). When the piggies are quiet, the brass connector is plugged.

If you want more detail on how to fix it, let me know and I'll post more details.

 

[dasigndr]

Thanks a lot JustnTym for replying,
We did do a number of checks with our Tech support team. They were extremely helpful.
We ended up having to change 7 heads the last few weeks. (they were due) however that did not correct all our problems. We also had to change all 5 bearings on the carriage. This corrected the "vertical banding" issue. I did clean that "little brass" fitting in the vacuum pump. Tjhis helped with the vacuum recovery issue. We are still having fading ptrints issues which thay are thinking has something to do with the way the media is fed. We cleaned all our gritt rollers and it seemed to help a little but we are still having "blotchy / faded" prints. Only at the beginning of my prints though.
So I will keep you posted as to what the final result will be.