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Need Help One line of magenta stops working, strange issue

Discussion in 'Mutoh' started by marco-it, Jun 13, 2020.

  1. marco-it

    marco-it New Member

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    Jun 11, 2020
    Italy
    Hi everyone, I'm facing a very strange issue with my VJ1204. One line of magenta stops working btween a print and another (due to automatic cleaning), not entirely, but approx an half. The only way to restart the line is perform a LittleCharge process, normal or strong cleaning not help. After the LittleCharge nozzle check prints perfectly and the machine works for meters.

    Here some informations about machine and what I tried:
    - The printhead is approx 2 years old, I replaced it by myself;
    - Maintenance station is less than 1 years old (replaced by year basis, in November);
    - There's a contiunous ink supply system,
    - Tried to replace the dampers and switch the 2 magenta dampers but the issue is on the same line at the printhead, so I think the problem isn't airleak in the damper or air bubbles in the tube;
    - Tried to clean the manifold at the top, without removing the printhead;

    I thought the problem still reside in the manifold, but I'm not sure disassmbling the printhead is a good idea...

    What do you think? Any suggestion? Thx in advance for your help!
     
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  2. Jim Hancock

    Jim Hancock Member

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    Nov 11, 2008
    Delray Beach, Florida
    Did you switch the magenta dampers positions or did you replace them? As the 1204 splits each color ink line at the head, switching them may not tell you anything. If you have replaced them, be sure all the ink line connections are tight. Did you replace the ink line O rings on top of the dampers? These can cause air leaks if reused. Also suggest checking the manifold posts by removing the magenta dampers, clean them with a swab dampened with cleaning fluid, inspect them with a strong light looking for any cracks and put your fingertip on top of each post and wiggle slightly to see if there is any movement, indicating a crack. A pic of a file showing the issue and nozzle test print done immediately after the problem occurs will be very helpful in diagnosing your issue.
     
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  3. marco-it

    marco-it New Member

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    Jun 11, 2020
    Italy
    First of all thank you for your reply.
    Both, I switched positions and replaced the damper. Can you explain me why switching dampers may be unhelpful diagnosing the issue?
    The o ring is the same, not replaced, unfortunately my supplier did not have them and the manifold as I can see is in good condition (no cracks or anything else).
    As soon as I can, I will post an image of the noozle test.
     
  4. Jim Hancock

    Jim Hancock Member

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    Nov 11, 2008
    Delray Beach, Florida
    The reason switching the position of the dampers won't help much in this case is they share a common ink line just a few inches away, so any air leakage is common to both dampers. Did you replace one damper or both? And where did you get them? You can get OEM, good quality aftermarket and crap quality aftermarket dampers. As far as the O rings and dampers go, try here - https://www.solventinkjet.com/search-results-page/o%20ring . I have bought quite a few different dampers from them and so far haven't had any issues and their prices are very reasonable and they ship quickly. You will have to see if they ship out of the country though. Not saying dampers are your issue yet, but troubleshooting these issues is sometimes a process of elimination, especially ink dropout problems, as there are so many things that can cause the same issue. Will look for pics, hopefully of some jobs where you had ink loss, as well as the nozzle test. A good tech can tell a lot from the prints showing the problem.
     
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  5. BigO

    BigO New Member

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    Apr 7, 2020
    Texas
    Inspect your flat cable (ribbon cable) for damage, when in doubt, switch it out. I got som cleaning fluid on the connector and it did all kinds of wonky things. Replaced $10 ribbon cable and used a little air to clean out a connector. Back in business. I read somewhere they are only designed to be plugged in 5x before pin failure. I can’t recall the source so take that with a grain of salt.

    As far as the dampener, in my experience the expensive ones last 2-3 months longer vs the “chinesum”. I purchase in bulk and switch every 6mo. The difference in quality is minimal so I use cheap ones unless I get issues.
     
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  6. marco-it

    marco-it New Member

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    Jun 11, 2020
    Italy
    Both. Unfortunately (or fortunately :)) I'm living in Italy and can't buy from solventinkjet.com, I buy cheap dampers from digiprint-supplies (€ 2,00 each) and no trouble as far as now. If switiching not help diagnosing, the problem can be actually the old o-rings.
     
  7. marco-it

    marco-it New Member

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    Jun 11, 2020
    Italy
    Can be as you say, but I'm not so sure because after a little ink charge the machine works for hours until pump perform an automatic cleaning. In my opinion is a ink flow related issue.
     
    • Like Like x 1
  8. marco-it

    marco-it New Member

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    Jun 11, 2020
    Italy
    I resolved the issue and I post my experience for anyone who can find it useful.

    A friend of mine gave me some new orings, so I replaced the old two on both magenta lines. During the operation of ink charging I noticed that in the capping there was only a little quantity of ink, so I decided to replace the entirely maintenance station (fortunatley I had got a new one). Inspecting the old MS, I saw an evident break in the rear part.

    I'm not sure if the issue was caused by the MS or orings, but with these maintenaces I'm now fully operational again!

    Thank you all for support!
     
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