Need Help Vertical banding

[Peter Martins]

We think we are fairly hot at fixing latex printers.

But we are stumped by this.

We have a machine which when printing solid blocks of colour across the whole media produces a sort of tonal vertical band. We replaced the belt and cleaned the carriage rails c
Cleaned the bushes and replaced the lubrication pads.

It seems a little better, but not good enough.

Any ideas?

 

[Dan360]

Having the same issue, I've tried many things without success and techs seem to ghost me when I ask about it.

It's not bad enough to rerun jobs but bothers me enough just knowing it's happening.

I'm planning to replace the encoder strip when I have the time.

 

[Jester1167]

A picture would be helpful. A couple of things come to mind, encoder being one and the media buckling in that location would be the other. Drastic differences between the pre, print, and post heaters can cause the media to expand between the pinch rollers. As the printhead travels over those peaks, the distance between the printed dots will change, causing a distortion in the color.

 

[balstestrat]

Peter Martins Dan360
Lets see the pictures of the issue. My guess is Dan you are most likely wasting money by replacing the encoder but hard to say without seeing first. It's super rare having issue with the latex encoder so that you would have to replace it. Cleaning usually helps.

 

[Dan360]

Doesn't show up too well on pictures but you can see it here. That's about a 12 inch wide section and it's even like this across the print. Greys, browns and screens are the worst. Which makes me lean towards something wrong with the LM/LC. But you can see it in all the colours to different degrees in calibration prints.

Everything's been cleaned several times since this started, all heads have been replaced since as well. Some medias it's more noticeable than others but it's happening across everything.

Any insight would be greatly appreciated, we've decided that we're going to keep this printer for a few more years so if I need to replace parts then I will.

 

[balstestrat]

Doesn't show up too well on pictures but you can see it here. That's about a 12 inch wide section and it's even like this across the print. Greys, browns and screens are the worst. Which makes me lean towards something wrong with the LM/LC. But you can see it in all the colours to different degrees in calibration prints.

Everything's been cleaned several times since this started, all heads have been replaced since as well. Some medias it's more noticeable than others but it's happening across everything.

Any insight would be greatly appreciated, we've decided that we're going to keep this printer for a few more years so if I need to replace parts then I will.

Well lets try to figure it out.
You are not running the vacuum too high no? This line is in printing direction right?

 

[Dan360]

Vacuum hasn't been changed in most of our profiles since we first set them up and they were printing perfectly for years. And playing with the vacuum didn't give noticeably different results.

Line is only vertical and straight.

It also just started one day and never got any better or worse which I find odd.

 

[balstestrat]

Vacuum hasn't been changed in most of our profiles since we first set them up and they were printing perfectly for years. And playing with the vacuum didn't give noticeably different results.

Line is only vertical and straight.

It also just started one day and never got any better or worse which I find odd.

What if you try to print this at the same position with the media you have it worst.
Then take a some good pictures of it and if you see any strange spots.

https://latexregistration.heleni.me/docs/HP Control Print -30x20inch.pdf

 

[Dan360]

What if you try to print this at the same position with the media you have it worst.
Then take a some good pictures of it and if you see any strange spots.

https://latexregistration.heleni.me/docs/HP Control Print -30x20inch.pdf

Thanks, I'll give it a shot tomorrow and see what I get. Printer is tied up for the rest of the day.

 

[WYLDGFI]

which printer is this specifically? We used to get vertical bands on our old 850s. Consistent across the entire printed area or specifically just a certain area on the platen?

 

[Mandi Nickerson]

I have seen this on our HP when the vacuum is too high. I would suggest reducing the vacuum and printing a test.

 

[Dan360]

which printer is this specifically? We used to get vertical bands on our old 850s. Consistent across the entire printed area or specifically just a certain area on the platen?

Ours is a 360, it's consistent across the entire print area.

 

[Dan360]

Attaching printed tests. Ran on IJ35c 10 pass 100% ink.

Also did one with the vacuum set to 0, prints were indistinguishable.

 

[balstestrat]

Attaching printed tests. Ran on IJ35c 10 pass 100% ink.

Also did one with the vacuum set to 0, prints were indistinguishable.

Well that is strange. Like there would be some sort of issue with voltage/unstable printheads.
What's all that's been done? All the printheads including OP has been replaced? Encoder obviously has been cleaned (I don't think that's the issue)?
Really could be anything I guess. Vertical banding is super rare and usually related to the vacuum or heat/curing. And if it just started one day suddenly, it's even more troublesome.
It could also be because of low air humidity. If it started when the cold air started and humidity dropped, it could be that the ink is drying too fast. I know, sounds wild.

HP also added this air diffuser thing in L365 which L360 doesn't have. I can't remember why they added it but it was for sure something like this that you have. Now that also doesn't just "start" one happening one day but was from day one.
It's actually a add-on part that can be added to L360 as well but I just can't find any info on it right now.
Found it, this could be the solution to you really. There is just no explanation why it started just one day.
And I have NEVER seen vertical banding in L365s which all have these diffusers.
Part: V8N83-67006 PZ Air Clip Diffusors SERV

 

[Dan360]

Yup, all heads have been replaced, encoder cleaned, encoder sensor cleaned, vacuum holes in the platen cleaned, heater vents cleaned, carriage cables checked, scan axis motor has even been replaced.

Another user mentioned those diffusers to me before, P Wagner I believe. I'll have to give those a shot. I still don't understand how this came about seemingly out of nowhere, something must have happened.

Thanks for all the input.

 

[WYLDGFI]

Trailing or data cable? This wasn't mentioned above.
I had same exact problem on my 850s years ago...just trying to remember what solved it.

 

[Dan360]

Trailing or data cable? This wasn't mentioned above.
I had same exact problem on my 850s years ago...just trying to remember what solved it.

Haven't looked at that as an option, just replacing it alltogether?

 

[WYLDGFI]

balstestrat may want to chime in on that option. Again, I don't recall if the cable or the motor fixed our issue back then.

 

[balstestrat]

I have low doubts that it would make issue like this... I guess there could be some really tiny signal change if the cable was damaged but who knows.
Like I said, could be anything. You just have to have a pile of parts and start testing.
Trailing cable can be easily checked but that doesn't really tell much if there were internal rupture in the cable.

Those test look so good that I would just try the diffusers. Easy and semi-cheap.

 

[Dan360]

Thanks guys, ordering the diffusers. Will report back with results next week.

Again, much appreciated.