JV33-160 banding / streaking issue

[signcode]

Hi there, I have been a frequent visitor to this forum but this is my first post. For the past week nearly all solid spot colours in our prints have shown banding and also some streakiness where the colour kind of fades in and out for a few passes. It is worst in the browns, oranges and burgundies, not as obvious in blues and greens but its still there.

To give you a bit of info on our machine, it is nearly 2 years old, the heads were replaced after 6 months (I'm not 100% sure why, I wasn't working here are the time). We are using ECO-HS1 inks, printing from Rasterlink Pro3 using a generic profile supplied by Mimaki - 1440x1440, 8 pass, uni direction. Our print room is air-conditioned to keep constant temp/humidity all year round.

Of course this has happened at the worst possible time, we are half way through a very large job for a museum so I need to find a solution that isn't going to effect the colours or make a noticable difference to the quality as they need to match what we have already produced.

So far we have tried:

Replacing the capping station - no difference at all
Changing the heater setting - no noticable difference from raising or lowering the temp
Difference print resolutions - slightly better on lower resolution but still not what we would consider passable
Converting files to bitmap, converting spot colours to CMYK - this of course changes the colours but the banding/streaking is still there
Printing from a different RIP program - only a slight improvement and too much change to the colours
Printing blocks of 100% cyan, magenta etc to see if one particular ink was causing the issue - they actually all printed fine, no sign streaking or banding
Drop_pos adjustment - no difference
A million media comp adjustments - still can't get rid of the banding
Tested the pump - seems to be working fine

Our test prints are fine, there are no lines missing.

The dampers have never been replaced however our tech is sure they aren't causing the problem. I'm actually waiting on another tech to come in today for a second opinion. In the meantime any help/suggestions would be very much appreciated.

Thanks in advance, Shelley

P.S. I hope you can see the issues in the photos ok, the orange print has been matt laminated so the banding is not as obvious in the picture but the streaking is there

 

[bmw_ante]

In what direction is theese "banding lines" Scan or feed?
Is the print head guide lubricated? so the printhead runs smooth?

1.If in scan,, Clean the linear encoder and its sensor
2.Try adding a dry times between scans (If it would be a damper problem, that ink does not flow good then this would make it print better)

I would have changed the dampers if the machine is 2 years old anyways...

 

[signcode]

Thanks for the response, its scan direction sorry I should have mentioned that. I will try your suggestions in the morning. Tech#2 first suggestion was the dampers, he is coming tomorrow to replace them.

 

[Rooster]

What inkset are you running? Dual CMYK, CMYKLcLm, white ink?

 

[Letterbox Mike]

I've brought this up before, but the first thing I would do is try a different profile. We get by far the best results on our JV33 with a 540x1080 profile (really any). I'd almost bet money this would solve it.

If not, I second the damper notion. It looks like a mild case of ink starvation, part of which the resolution could also help clear up (it seems like higher res profiles require more ink than the ink train/dampers can actually deliver on this printer).

Just a thought.

 

[signcode]

Rooster - its dual CMYK

Insignia - spot on, it has turned out to be a profile issue. There are no 540x1080 rasterlink profiles available for our inks but 1440x720VD, 8 pass, bi-direction, fast print has worked a treat. Colours are slightly different but close enough that we can live with it.

Tech#2 replaced our cyan ink cartridges and dampers. Apparently our cyan inks were from a batch that was known to be faulty. He checked the other dampers but they were fine so he left them in there. He also did some adjustments, slant adjust, drop pos etc which improved the banding but the streakiness was still there until we changed the profile.

Glad to be back on track for the moment, a bonus is the new profile prints a lot quicker! cheers

 

[Letterbox Mike]

Good to know. We have found the DX5 head is very sensitive to certain resolutions. We've more or less stopped running anything above 540x1080, we get zero banding or dropout at that, but typically anything higher and we'll start to see some print aberrations. And the upside is you can get good band-free prints with a 6-pass high-speed bidirectional profile which is obviously hugely faster than an 8-pass profile.