JV3 banding / dropout / starvation with no visible cause?

[genericname]

Noticed a stripe of lighter colour in a single pass on a display we printed, only in the are of the image that was red. Ran a test print, and sure enough, all colours are fine except magenta. Prints perfectly for about six or seven inches, then a light stripe. Sometimes it's just the one, sometimes it's every few inches, and sometimes it emulated ink starvation, in that it starts gradually, and either gradually goes away, or persists across the whole print once started.

Here's what was done that hasn't solved it or pinpointed it:

1. Pump repaired last week due to unrelated issue (line burst). Now works flawlessly.
2. Test pattern printed. Flawless.
3. Cartridges swapped for full ones.
4. Cartridge assembly examined, no cracks or receded feed pin.
5. Encoder strip and sensor cleaned (even though I knew this would do nothing).
6. Dampers swapped, stripe did not travel.
7. Lines inspected, no air bubbles present.
8. Head replaced.

That last one is where I hit the wall. I'm sick as a dog, and can't be bothered to stress about this thing, but we have a lot of work coming down the line, and we can't run one printer alone.

Any ideas aside from the obvious?

 

[genericname]

No luck so far, but with everything I've done, it can't be an ink, head, line, damper, or o-ring issue, so it's either software or hardware.

In the interest of not ripping out the main board, I tried to do a parameter swap with our other JV3, but I keep getting errors when trying to pull information from the functioning one.

Anyone familiar with the FW Update tool? The transfer seems to be working, and even gets to the point where I can save the CSV file, but on the printer end, it beeps, and displays "ERR PRM.SHORTAGE" on the screen.

 

[genericname]

:iamwithstupid

Right. Wrong setting set to pull data from the printer. Either way, null result. Pulled params from working printer, pushed them to the borked one, no change.

Set my params back, then decided to swap the slider boards. No change.

I'm left with only the I/O board, and the main board as culprits at this point.

 

[MikePro]

you've done everything I would have, thusfar.
still trying to throw out some ideas, crazy or not, but I'm stumped right now.

 

[TheSnowman]

Mine acted like that right out of the box, and it ended up being the pump in the end. This is mind boggling. Seems like if it starts out fine, and only does it later in the print it'd have to be something in your ink system.

 

[Solventinkjet]

It's possible that while printing something is hitting or collecting on the bottom of the head. Make sure the wipers are very clean and that there is not even one piece of dust or fibers/hairs that are collecting. Other than that it could be a head cable issue. You can always try a data swap to see if the issue moves to a different head.

 

[particleman]

Air is getting into the system somewhere... finding it is the trick. I don't think this is software related at all. I would've said cracked manifold or o ring on manifold but you changed the print head? What about the o ring on the damper?

 

[ChicagoGraphics]

I had something like that a couple of years ago on my JV3 and I was told by a tech to clean the encoder strip and sensor and the problem went away instantly.

 

[genericname]

Already did a data swap, and the problem stayed with the Magenta head.
Can't be air, o-rings, or dampers either, as I swapped the dampers as well, and the problem stayed put. Also, yep, changed print head.

Encoder strip and sensor was one of the first things I checked and cleaned too.

Edit:
Giving it a rest for the weekend. Just pushed forward a big overnight print, and got some bad news over the phone. Screw this day.