banding on plates

[wonderings]

I am having trouble with our presstek dimension excel ctp. Using Anthem Pro plates.

I am getting banding marks down the plate, it appears to be a laser issue as its in columns down the plate, which appear to be the width one laser burns. I am somewhat new to this, we have had our Dimension for 2 years now. I am not sure if its actually the lasers or something in the wash. If the plates are scrubbed by hand well, we can pretty much get rid of this. I am having issues with laser calibration, it does absolutely nothing. I follow the manual step by step and get figure out what I am doing wrong. Does this problem sound like a laser issue or something to do with the rollers and how they clean the plates in the water bath?

thanks

 

[overtwo]

I would first suggest calling in a service tech. Then go from there...

 

[digiservice_it]

Hi wonderings,
I think (and hope...) you have a problem on the washing solution....
Keep a new solution and try again.
Regards,
Luca Lombardo

 

[wonderings]

Hi wonderings,
I think (and hope...) you have a problem on the washing solution....
Keep a new solution and try again.
Regards,
Luca Lombardo

Its cleaned by water, no chemicals.

As for calling in service, if I cant find a solution we will do that, but they are not cheap to have come in. So I am doing what I can first before shelling out the money for tech to come in. Going to try and adjust the brush pressure in the waterbath and see if that helps.

 

[Elewis]

It can be one of three things

1) A dirty sensor where the hose comes out of the dimension
2) partical filter needs replaced (will cause air-flow errors and stops imaging half way through the process.
3) ???

 

[KimSaks]

One way to rule out your wash processor is to feed the plates in at an angle or 90 degrees if possible. If the anomolly changes direction then the problem is in your plate processor. If not then it's in your plate imager.
If it's your imager you might want to check not only the calibration and alignment of the lasers, but also the cleanliness of the imager. I've seen a lot of issues such as you describe that traced back to dirty lenses and lasers.
Contact me direct if you wish...
KJ Saks
[email protected]

 

[wonderings]

thanks for the suggestions. I am going to give the CTP a good cleaning today and try again to do some laser calibration. I cant feed the plates in any other way as they are large 23 x 29 plates that only feed in one way. I think the lasers just need to be adjusted. Thats my other problem, when I try to do any calibration, nothing seems to work. I have done it many times with no issue. I am sure there is one little step I am forgetting. Going to give it a go today with a fresh head.

 

[DCurry]

2) partical filter needs replaced (will cause air-flow errors and stops imaging half way through the process.

Had a similar issue a couple weeks ago, and it was the filters in the vacuum unit that needed to be replaced. Wasn't cheap (especially because we had them overnight the filters to arrive on a Saturday morning) but it fixed the issue. Another symptom of that was that the GUI kept quitting out - had to relaunch the GUI 3 or 4 times per plate to get it to run.

 

[wonderings]

Had a similar issue a couple weeks ago, and it was the filters in the vacuum unit that needed to be replaced. Wasn't cheap (especially because we had them overnight the filters to arrive on a Saturday morning) but it fixed the issue. Another symptom of that was that the GUI kept quitting out - had to relaunch the GUI 3 or 4 times per plate to get it to run.

Our Filters were changed a few months back, definitely not cheap and a terrible design by presstek. I guess they found a good way to charge $900 for a filter in a metal box. We have the GUI cut out as well, because of the filter needing to be changed. It shouldnt be the filter, it should last alot longer then a few months.

 

[spectrecom]

This is a very common problem with the Dimensions, the lasers need to be balanced every few months. You'll have to call Presstek, sorry.

 

[David Galway]

If the marks disappear after a hand scrub and wash, I'd be looking at the washer. Any Dimension-based artifacts will survive the wash and scrub process in my experience.
Perhaps the water processor feed rate could be slowed, and/or the speed of the scrub rollers increased. There may be a roller pressure issue as well, but be careful here, if you go a little over tolerance the plates will buckle and jam.

 

[western411]

We have the vector unit which is a different plate but had the same problem. Our wash unit has a slottted under plate. We found the wash unit brush roller would build up more in areas where the plate was soild and the plate would build a crust around the edges as water passes through. The combination of the two gave us the same weird streaks. We began a program of dumping the water sooner and cleaning both the under wash plate and the brushes every 3-4 days and the problem went away. We also clean the laser mirroro every Mon-Wed- Friday as they attact dust and we never had the problem again.

 

[aedsgn]

If the marks disappear after a hand scrub and wash, I'd be looking at the washer. Any Dimension-based artifacts will survive the wash and scrub process in my experience.
Perhaps the water processor feed rate could be slowed, and/or the speed of the scrub rollers increased. There may be a roller pressure issue as well, but be careful here, if you go a little over tolerance the plates will buckle and jam.

I agree with this, although we have a Presstek Dimension Excel 450 and an Anthem washer. I think we'd have to diagnose the problem based on what the banding actually looks like. Are the bands light gray or are they 100% black stripes when the plate ejects?

If it's the former and you simply have darker gray bands, then it may be that the problem can be fixed by adjusting the power to the laser diodes using the Diode Current Adjustment program. I end up doing this about once a year. A Presstek technician walked me through the process and it's quite simple once you know how it works.

Also, Presstek technical support is absolutely top notch.