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jv33 - hope it's the pump. Started with yellow

Discussion in 'Mimaki' started by petesign, Jan 15, 2013.

  1. petesign

    petesign Very Active Member

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    Feb 27, 2010
    Hoover AL
    I figured I would make a new thread, rather than hijack another one.

    Yesterday, Magenta dropped a little on us, I did a head soak, and it came back. Today, yellow just disappeared mid print. It didn't slowly fade out, it just shut off mid print. So I tried the head soak again. Nothing. Pulled the cover, checked dampers, there was yellow flowing to both of the yellow dampers, and I could get ample ink by pressing it in. (i know those are gravity fed)

    I was told by the tech support folks that it is because of the pump. Here's what makes no sense on that, the yellow nozzles are in the center, between the cyan and black nozzles on each side. Why would just those sets be affected by lack of suction?

    So, in my infinite wisdom, I started swapping dampers. Black for yellow... now the black doesn't print either (even with the dampers swapped back) cyan for yellow ... nope nothing there either. Tried an ink fill, those didn't come back. Tried pushing a little bit of yellow ink through the head on the yellow nozzle, and guess what, there was a little yellow on the next test print.

    Pump will be here in the morning. Odds on it fixing the problem?
     
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  2. Vinylman

    Vinylman Very Active Member

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    Aug 15, 2005
    Berlin Center, Ohio
    Did you check the edges of the docking station? If there are ANY cracks, even minute, that could be causing a loss of vacuume. I always try to do a process of illumination before any wholesale changes. A new pump is fairly inexpensive, and worth the time to swap in. If that doesn't take care of the problem, look to the docking station next.
     
  3. Robert M

    Robert M Very Active Member

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    Jan 23, 2007
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    20%

    I think your original problem was the need for a new cap top. To check it all you need to do is draw ink from one of the lines between the pump and cap (you need to open the switches for the individual ink lines first). If you pull down a mix of ink and air the cap may be bad or not seating right. Seems like with the JV33 and CJV printers, megenta goes out first with a bad cap. Switching around those dampers you may have opened the connections from the ink line to the dampers allowing air to leak in. You may want a tech to come out if the pump and cap don't fix it.
    We have the caps at www.solventinkjet.com
    Hope I'm wrong and it all works out with the new pump.
     
  4. SightLine

    SightLine Very Active Member

    I agree with Robert. Also the JV33 and CJV30 machines are not gravity fed. They are very much reliant on negative pressure created by the peristaltic pump. Without the negative pressure the ink system cannot overcome the spring pressure valve in the damper. Actually it will take even more pump cycling to build that pressure back if you manually press the valve in o these dampers. This is also why you cannot simply draw ink on these with a syringe without first somehow opening the solenoid valves behind the cartridges. You are pulling against a closed valve. Very very often problems on these are indeed due to the capping station no longer making a perfect seal.

    If you are replacing the pump, that can't hurt but go ahead and replace the capping top while you are at it.
     
  5. petesign

    petesign Very Active Member

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    Feb 27, 2010
    Hoover AL
    Wow, I wish I had ordered the capping station at the same time :( Fingers crossed that the pump works, we have an install tomorrow and Thursday, and a little less than half printed before it went out.

    Thank you for all of the information, you guys rock.
     
  6. petesign

    petesign Very Active Member

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    Feb 27, 2010
    Hoover AL
    Ok, so I am going to Mimaki and picking up a cap this morning. Turns out they are about 2 hours from me. I'd rather be safe than sorry, and this job has to go out tomorrow. I did a little test, opened the valve behind the ink cartridge and opened the damper to see if ink flowed through the head. Sure enough, yellow started to drip.

    I couldn't get any to drip on the colors that dropped out yesterday after pulling dampers, but didn't wait a really long time. I'm going to replace the dampers, the cap and the pump when i get back this afternoon. Is anyone interested in me posting pics on how to do it as I go?
     
  7. Vital Designs

    Vital Designs Vital Designs

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    May 29, 2005
    Dalls, Texas
    I have chased a very similar issue. I replaced dampers, cap-top from a 3rd party supplier. I still had intermittent ink starvation issues. Ink was not drawing through the dampers consistently. One yellow bank in particular would go away when I printed large areas of yellow. I had replaced the dampers twice.

    I decided to order genuine Mimaki dampers. You can feel the difference when the attach to the head manifold (they seat tighter). Ink instantly pulled through them and the printer is perfect again.

    I learned my lesson not to chase ink starvation issues with non OEM parts. $6 vs $46 for dampers is tempting but it is false economy.



     
  8. petesign

    petesign Very Active Member

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    Feb 27, 2010
    Hoover AL
    It was the cap :) printer is running great. I replaced 4 dampers, and the cap. It took one cleaning and it was printing 100%. Yay. Was too tired after driving 8 hours to remember to take pictures (turns out Mimaki's headquarters are on the other side of Atlanta so it was a haul). I cant believe it was the cap... I was just sure it was something different. Thank you to all of you for the help and input, this job was saved because of signs 101! Also big thanks to Grimco, and tubelite's tech Jeremy for their help.
     
    Last edited: Jan 16, 2013
  9. Robert M

    Robert M Very Active Member

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    Jan 23, 2007
    colorado
    Cap top

    Once a week I'll get a customer who just will not believe that a cap could be the problem. Logic makes you think that if the cap goes bad it will cause all the colors to drop out. I think that where the cap is leaking air is where the drop out starts.
     
  10. petesign

    petesign Very Active Member

    1,191
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    Feb 27, 2010
    Hoover AL
    You were right on the money. Put in the pump yesterday morning before I left, and it didn't do anything, after filling the dampers and one cleaning cycle, all nozzles were printing perfectly after replacing the cap. I have looked all over the old cap, and see nothing wrong - it was just worn out. Amazing how tight that tolerance is and how bad you think things are going to be, and it's such a simple fix.
     
  11. SightLine

    SightLine Very Active Member

    Good to hear you got it up and running! Yeah the cap is deceiving.... can look perfectly fine even under very close inspection but still be worn out. Make sure to clean the original pump out and keep it on the shelf as a spare. Never know when you might need it but it will probably be quite a long time since you now have a new one in.
     
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