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Help - Problems with one Magenta bank loosing 20-50% of nozzles...

Discussion in 'Mimaki' started by ScotJ, Sep 21, 2008.

  1. ScotJ

    ScotJ Member

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    Aug 14, 2008
    Its almost like clock work - a year ago around this time I had a jv3-160 that was having nozzle crap out on my cyan cartridge. After alot of fiddling around and loosing a few job i traded up to a JV33 with a 1 year warranty.

    It runs problem free until about 2 weeks before the warranty is up - go figure!

    I've attached a few test prints - as you can see its not always the same bank. and its been getting worse and worse. I just did an ink fill-up, problem went away, and then I printed about 80 or so sq ft and it was back again.

    What are some probably causes? Dampers? And if so - how hard are they to change on this machine?

    My warranty covers parts only - so I'll have to do the labour unless its really tricky ( I want to avoid the $150/h tech rate)
    '

    THanks in advance!
     

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  2. ScotJ

    ScotJ Member

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    Aug 14, 2008
    Also- just for reference, I am running OEM inks, and have 2 nozzles that don't fire out of the entire 1440.
     
  3. Rooster

    Rooster Very Active Member

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    From my experience large blocks going out like that tends to be the result of getting some air into the lines. This usually occurs at the damper seal or the cartridge seal. The dampers should probably be replaced if the machine has seen a fair amount of use.

    If it's in a dual CYMK set-up on a JV33 air contamination could also occur at the crossover point in the ink lines where the two cartridge lines merge into one. If you tend to remove and re-insert the same cartridges I would try a new cartridge(s) to see if that cures it. You will need to print enough ink to move any air in the lines all the way through the system. If you can inspect the dampers look for air bubbles in them.

    Dampers are pretty cheap. Buy a couple of sets so you can have some spares when you replace the ones in the system now. Be very careful when removing the dampers as they plug onto a plastic pin on the print head. Any wiggling, or side to side movement can break that pin off and you'll need to replace the entire head.

    MAKE VERY SURE YOU UNPLUG THE MACHINE FROM THE WALL before you start removing any parts on the machine. The mainboards have some milliamp fuses that are not replaceable and will blow easily. You do not want to replace a mainboard.
     
  4. ScotJ

    ScotJ Member

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    Thanks for the info - yea we are reasonablly high volume, probably 50k+ square feet have gone through the machine if not more.

    I'll go grab the damper tomorrow and try the swap. hopefully that fixed the problem.


    As for the seal on the cmyk joint point, is that an easy switch?


    Lastly - doesn't anyone have a link to the damper swap manual? Ideally a service manual link :D thanks!
     
  5. Rooster

    Rooster Very Active Member

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    I believe the ink line joint is just a couple of brass nuts on a plastic fitting sealed with some small o-rings. Replacing the o-rings should be all that's required to renew the seal. Unless they are loose, I wouldn't think that joint would be the source of the air contamination. It's usually the dampers that go, or overuse of a refillable cartridge that causes this issue.
     
  6. ScotJ

    ScotJ Member

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    Aug 14, 2008
    Well I pulled off the damper and changed it ($60 bucks here in Canada!)

    I was able to pull some ink through, but with alot of fight.

    I took the ink line of the damper, and un-hooked the cliper aperatous and was able to pull ink easily with the syeringe. However, when I put the clip on piece ( piece that connects the ink line to the dampe) [point b in the my picture] I was't able to pull ink through. And if any came through, it was a HUGE fight. Is this normal, or could this be the route of the problem? I don't have that part handy, but I'll get one tomorrow.


    By the way, with the new damper, I get the same problem as I was before.
     

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  7. signage

    signage Major Contributor

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    If I'm not mistaken there is a small o-ring that goes over the line and inside the brass not that when tightened down helps seal the connection! Make sure you didn't loose this small o-ring if it is there try cleaning it.
     
  8. Rooster

    Rooster Very Active Member

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    I'm having a little difficulty understanding exactly what it is you're doing as far as where you're trying to draw ink from with the syringe.

    Are you saying it draws easily from point A and not from point B? Did you try to draw from the damper where it plugs into the head?

    When you say difficult to draw ink, do you mean it's difficult to pull the syringe due to too much suction, or do you draw the syringe easily, but no ink is pulled?

    Is the problem you're having drawing ink through the same on another line?

    If you cannot repeat the problem on another line and you've located the part in question that seems to be causing a restriction it would seem you've found the problem.

    Partial restriction of the line could cause the same initial problem due to ink starvation. Instead of the head drawing air and ink, it just cant get enough ink to fire all the nozzles, but still gets enough to fire some. Clogged lines or fittings with OEM ink cartridges are a rare occurrence in my experience. That doesn't mean it can't happen though.

    From looking at the picture again it seems the tabs on item B are at an odd angle compared to the other dampers. Are you sure the part is seated correctly?
     
  9. mimakitech24

    mimakitech24 Member

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    are you opening the valve before you try to draw ink through the line? pretty important question to ask because if the valve is closed...well then you can't draw ink through a line..

    :)
     
  10. ScotJ

    ScotJ Member

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    Well turns out I didn't know about the solonoide on the back of each cart (to use to my JV3 I guess).

    I replaced the valve assembly on the top of the damper, and still getting the problem.



    and yes- I did have the tab mis-aligned, but that has since been fixed.

    One tech mentioned possibly slitting of part of the feed hose and replacing the brass fitting and o-ring. Might that help?
     
  11. The Big Squeegee

    The Big Squeegee Major Contributor

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    If you see air in the line above the damper right after you pull ink up to it, you have an air leak. Never tighten the brass nuts with a wrench. The extra torque can crack the threads.
     
  12. ScotJ

    ScotJ Member

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    Aug 14, 2008
    Well thats the thing - Im not really getting air anywhere (visibly atleast) I know all I need is a microsopic amount mind you.
     
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