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Help JV33 black losing black ink

Discussion in 'Mimaki' started by strandt, Jun 26, 2012.

  1. strandt

    strandt New Member

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    Jun 26, 2012
    Hi everyone...new to this forum. I have an ongoing problem with my black ink. I use a bulk system with water-based ink. For months now my black has been dropping of after 2-6" of printing. I have cleaned the damper, cleaned the head, cleaned the line but the problem seems to still persisit. When I switch the black position on the head with another color it works for awhile(like I mentioned above) and then drops off again. I have been rack ing my brain as to what to do next. Please an advice wouls soooooo be appreciated.:banghead:
     
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  2. Robert M

    Robert M Very Active Member

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    cap top

    First I would change the cap top, second if the bulk system has the adjustment, try changing the height of the black ink supply to a lower position
     
  3. 4R Graphics

    4R Graphics Active Member

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    I use solvent ink but have had a similar problem but mine will print for about 3 feet.

    I am not sure what is causing it but I have found that when I pull the dampner on both black lines the little pouch on the back top righ is indented and it should not be.

    What i have done is prop open the line locks at the cartridges and put a syringe in both black dampners (ihave 2 and you have to do both at the same time or one draws from the other) hold dampner upsidedown as far as I can and draw ink into the syringe then do the other dampner then remove both syringes and the then indented pouch is now bulging (like all the other colors do) put dampners back on remove props on line locks do a soft or normalclean and all is good wont have anymore problems.

    My problem is if the printer sits for a day or so it may do it again never had this problem before just showed up about a week ago and yes the cap and the dampners are only 2 months old.
     
  4. DigitalPrintTech

    DigitalPrintTech New Member

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    Jul 3, 2012
    Whitewright, TX
    The ink delivery system on these printers really sucks with bulk ink systems.
    First I am going to say that open air systems cause problems, sooner or later you will experience ink delivery problems. Running actual cartridges will fix most ink delivery problems you are currently experiencing.

    But if you choose to run the bulk ink system, here is something that might help. (NOTE: if your machine is under warranty you need to ask if altering the ink delivery system will void your warranty)

    With that said, your not hurting anything doing this, you are simply designating a single ink line per cartridge rather than two lines sharing the ink flow between two cartridges. Let me explain

    If you pull the back cover from the ink bay, you will see the ink lines coming from the ink carts bay. Notice the CROSSBAR between the ink lines. This is a terrible design and will eventually cause problems with bulk ink systems. When your printer was installed, there should have been a small bag that has some ink line caps in it. These are for certain inksets that is supported by that machine (ie CMYKLcLm) but nobody I know that has one of these printers runs that ink configuration. So with that said, I would remove that crossbar between the ink lines and cap them. There is still an adequate amount of ink going to the dampers without the ink trying to crossover line to line. I know it sounds crazy but take a look back there.

    One more thing, make sure your ink filters on the bulk carts are clean and replaced on a regular basis.

    Hope this helps
     
  5. artbot

    artbot Very Active Member

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    when you do the damper swap, does the black channel perform fine at the new manifold position? if so, i'd ignore anything above the manifold. that said, you could have a clogged or cracked manifold. the captop encompassing all the channels makes it difficult to isolate a bad vacuum to a single ink line. there is a possibility that your cap top is getting tired too. but i just can't think of a circumstance (a crack, or low spot) that might be able to single out that channel. i assume the sequence of the inks is black first, right? i'd look at that side of the cap, it may not be coming up level. one way to test this on an old jv3 is to turn off all noise making things in the room (havac, computer fans, etc). now pull a vacuum with a syringe at the waste line. if you hear hissing near the head carriage you have a leak. but considering that you have a channel loss, i'd be listening on the top more than at the cap. a cheap $9 automotive stethoscope can pinpoint the exact leak point if it is audible.
     
  6. SightLine

    SightLine Very Active Member

    DigitalPrintTechs not on bulk systems is mostly sound BUT. If you are running dual CMYK as most are you cannot remove the H (crossbar) unions. You will lose half your ink channels if you attempt to do so. These machines use a solenoid controlled ink delivery system to switch between cartridges. These only draw ink from ONE of the 2 installed cartridges per color at a time. This is why from the factory these have the H unions on the lines. The only time the H unions are not used is if the printer is configured for anything other than dual CMYK.

    There are a couple of bulk ink systems that do not cause problems in the long run. The only ones are those that used a sealed bag system. Triangle has one out, Bordeaux has one, and Mimaki's very own MBIS bulk system uses a sealed bag system. I've gone over this before in other threads. The advantage to a bag system, is that as ink is used the bag of ink collapses. In this scenario the ink system performs as it should. With other bulk systems there is potential for extreme negative and positive pressures being put on the ink train. That will cause issues every time. An ink bag (just like inside a cartridge) collapses as the ink is used, with ink a rigid tank bulk system the tank cannot collapse, as ink is used a good amount of negative pressure is developed which must be overcome until the tank refills the sub cartridge. Does not matter if it uses a float or not, until the float moves some negative pressure is going to build.

    I have Triangles EcoBulk system on ours which uses 2 liter ink bags ink boxes. These connect to sub cartridges which also have an ink bag in them. Picture attached. Notice that the bags in the sub cartridges are partially visible, this is so you know for certain that the main bulk bag in the box above is empty, the sub carts bag will start to empty. When it does you simply close the clamp on the line to the bag in the box, pull it off the box, set a new box up, push it's needle into the bottom of it and re-open the clamp. Viola', no air introduced into the ink train, no ink sitting in a tank exposed to a bunch of air above it, no spills, no mess, NO pressure problems. Been using this for several months now and I have to admit, after using about 4 other bulk systems over the years (on a JV3 and JV33), every one has been problematic or messy in it's own way, ink bag bulk systems are by far the best and least problematic bulk systems you can get. Also note, since the sub carts are short 220ml ones you can ditch the big shelf on the printer there giving more room. :) Of course these have their own quirks as well. Triangles only uses 4 sub cartridges so you MUST reset the printer when the ink levels run down to 1 or the printer will attempt to switch to the 4 unused slots. Part of the install though is disconnecting the solenoids to those unused slots so it will not be able to try and draw air into the lines since there are no carts there.

    I'm actually thinking about maybe adding 4 more of the sub cartridges, reconnecting those 4 selenoid valves, and adding H unions between the main bulk ink boxes and the sub carts so each bulk box can feed 2 sub carts.
     

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  7. DigitalPrintTech

    DigitalPrintTech New Member

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    Jul 3, 2012
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    Sightline-
    I hate to say, but I have done this and it has fixed the problem with OPEN AIR bulk systems. If it alternates between carts, the ink lines are still being fed, no matter which cart or solenoid is open. So with that said, let me ask you a question because it appears you have some good experience with these machines.

    If all the green lights are on, doesnt that show the solenoids are open? If they are red then they are closed? Please confirm this. I will continue when you answer.
     
  8. SightLine

    SightLine Very Active Member

    That is incorrect, the lights have nothing to do with whether the solenoid valves behind each slot is open or closed. The light only indicate the status of the cartridge in the slot. Green light indicates the "active" cartridge, in other words which one the machine will be drawing ink from. Off indicates, cartridge present but not active, machine will switch to it automatically when the current active cartridge is empty. Red flashing, near empty, empty, or expired cartridge and printer will not switch to it. Solid red, empty or no cartridge present and printer will not switch to it.

    Listen to the machine when you start a print job, the green light is already on and has been on, the clicks you hear at the cartridge area are the solenoid valves opening. And they are ONLY opening on the active (green lighted) cartridges. This is also why you cannot simply pull ink from below the capping station with a syringe. You will get a little but you woudl also be causing massive negative pressure on the dampers and ink lines since the solenoid valves are all closed. The only time it is safe to do this is if you go into service mode and manually set the solenoid valves to open or pull the rear cover and manually tape them open.

    If you are running dual CMYK and remove the 4 H connectors, each of the 8 channels at the head will only be able to draw ink from the cartridge slot is is directly connected to. With half the solenoid valved closed this would be a 100% loss on that channel. Mimaki used the solenoid valves on these machines for a couple of specific reasons. One, they allow the machine to auto-switch between cartridges. Two, they control the pressure in the line making sure the dampers do not get overpressurized. If they were locked open the printer would simply have the older DX4 head style "dumb" dampers. DX5 dampers have a very sensitive spring loaded valve in them that works closely with the pressure in the ink train.

    Many still do not get this on the newer DX5 head Mimaki's (JV33, CJV30, JV5) and think raising, lowering the level of bulk tanks and whatnot will have some affect. That will only affect things up to the cartridges or sub-cartridges themselves. Due to the solenoid valves that will have zero affect beyond them unless you have bypassed them or somehow locked them open. If this is done you may as well change it to the older style dampers as the DX5 dampers are not designed for the free flow higher pressure of ink that way.

     
    Last edited: Jul 4, 2012
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