stumped, chronic vacuum leak at cap

[artbot]

hoping someone out there knows of some mimakinese secret to solving a vacuum leak at the cap. recently i broke down my printer, did some mods, put it all back together. did an ink fill (CMYKx2) and noticed that the K and C weren't filling. did the usual isolation, extensive isolation:

swapped cap tops
swapped dampers
swapped pump lines
even swapped head locations!
readjusted head height
brought capping station to factory height (couldn't really be height because other heads (M and Y) had no leak. but did it for scientific method)
brought capping station up .030 and .060 with shims
moved capping station around to other positions
then change out to new cap tops!
even took a head manifold off and retightened!

today i was really excited because i'd decided that my captops must be tool old and replacing the would do the trick (replaced all four cap+tube, not just seal) ...no. still hearing very tiny sucking air sound. grrr...

i'm stumped.

i've even used a homemade stethoscope to make sure that the air noise is coming from between the head and the captop.

what else is there to check? this isn't rocket science.

 

[Vinylman]

Since you have seemed to eliminate the parts closer to the capping station, perhaps it may be somewhere up stream. I would check or replace the "O" rings and double check the connecters on the tubing.

 

[ruckusman]

Try reversing the flow - What I mean by that is instead of say pulling a vacuum at the end of the pump lines, put some cleaning fluid on the parking pads to avoid gunk going backwards into the heads - then move the heads to park position and paint suspect or potential seal areas with liquid soap and see if you can spot any small bubbles

 

[MikePro]

recently had an air leak in my cyan and replacing the cap top fixed the issue. Buuut since u already replaced the part... I can't think of anything else to look into besides your connections.

 

[signswi]

brought capping station to factory height (couldn't really be height because other heads (M and Y) had no leak. but did it for scientific method)

This isn't true, because of how the capping station levers up to the suction position you could easily get suction on M/Y/K and not on C. Head might not be level or the capping station arms are bent or not clipped in correctly or whatever. Happens all the time. Probably not meeting the head perfectly square.

You've hacked at it too much to really be able to help without being there to look at it. Is the spring on the left lift arm still good (or missing?). Is that arm bent, or off it's connector? etc. Could also just try replacing the whole station, that's what we usually do, cheap part.

 

[ddarlak]

when i can't get an air leak to stop my last resort is to put the syringe on the drain ink line and put ink through the entire system with the mega force of the mighty syringe.....

absolutly no reason it should work, but 90% of the time i get the desired result...

 

[artbot]

i can pull fluid with a syringe, getting lots of bubbles, and a tiny hiss of vacuum leak. is a hiss common? don't remember ever hearing an audible sounding leak.

during a cleaning cycle, i get nothing. meaning the printer will not work properly over time. maybe i should pull ink through the head manually and then see if the hydraulic difference between dry and present fluid changes things up.

as far as changing out the entire capping station vs. changing the guts of the assembly. ...don't know how that can apply to a diagnostic method. it was fine coming off, wouldn't be broken going back on. i must have put it back togehter wrong.

now the part about the head carriage being level... is there a mechanism for adjusting the plumb of the head carriage? to me, that is the most suspect possibility.

 

[WrapperX]

No there should be no hissing sound. That lets you know that there is an air leak somewhere. And you shouldn't be getting any bubbles from the drain ink line pull with a syringe.

 

[artbot]

...the air is getting in right at the cap. i've heard it (with my homemade stethoscope). also, "where" a bubble comes from is the leak location. the system is perfectly sealed from the damers back. i've had the dampers hanging off the head carriage for days, they haven't gone down in ink level at all.

being that all the parts are new, every thing is sealed. i'm down to contact/angle. but, i've even tried gently tilting the carriage fore and aft but still see an unchanged amount of bubbles coming in below the cap, while hearing the leak.

 

[J Hill Designs]

is it because you raised the head to 4mm maybe?

 

[Mimaki man]

air

If the springs are not sitted correctly on the buttom of the cap if will drive a person crazy

 

[Rooster]

Did you happen to bend anything when you were modding the head height. You obviously know your way around the printer.

If something has twisted you'll be chasing the leak forever. Since you mentioned shimming it, I wonder about everything still being square.

 

[artbot]

@jhilldesigns ...i've dropped the head back to factory... currently even set at the "thin" media height, which it's never been at.

@mimaki man. i'll check the spring issue.

appreciate all the input from everyone.

 

[J Hill Designs]

since you dropped it back to factory, did you take your shims out? might be buckling a captop lip or something...

 

[artbot]

i've tried every different combination. it has a facotory shim in there right now, but it's been at every possible different height combination. and i've moved the targeting position every possible way as well. i'm stuck with angle of contact or approach.

 

[signswi]

Chapter 4-2-5 in the JV3 maintenance manual. 4.12 has a bit about adjusting cap height individually, might be useful. There's also a section in Maintenance mode on the machine itself where you can adjust the head height, absorb position, flashing position, wiper position...gotta be something in there.

I'm sure there's also a way to plumb the head itself on the rails, but I'm not sure how. Probably in the manual somewhere.

 

[artbot]

@jesse i feel stupid. i'm like, "i don't need no stinking jv3 service manual... what can it have that i don't know"... sounds like there's a lot more dialing in to do. thanks for the suggestion. tired of looking at this giant purple weight.

 

[ruckusman]

You may well benefit from walking away from it for a couple of hours and doing somerhing else that occupies your mind entirely.

When you come back to it approach it from an entirely different angle, so walk up to it from the left side instead of right, or vice versa.

as far as changing out the entire capping station vs. changing the guts of the assembly. ...don't know how that can apply to a diagnostic method. it was fine coming off, wouldn't be broken going back on. i must have put it back togehter wrong.

I once couldn't get an old BMW to fire after reconditioning the head, last thing was the distributor, which was keyed and COULDN'T go on incorrectly, well it had and that assumption was very embarassing for me

 

[artbot]

that's what i'm doing. i've got a lot of things going on and will do battle later.

again appreciate all the replies.

 

[Jim Hancock]

Your problem is most likely a centering adjustment between the print heads and the caps. You can test this doing the following: 1. Power off the printer. 2. Clean the bottom of the print heads gently with cleaning fluid. 3. Wet the edges of the cap tops with black or waste ink. 4. Manually park the print heads on the capping station for a moment. 5. Move the print head carriage off the capping station and examine the bottom of each print head with a mirror and flash light and look for the ink mark left by the cap top. This will tell you if the caps are touching the silver frame on the print head, which will cause an air leak. Most likely the caps will be too far to the left on the problem heads. There is no left-right adjustment on the JV3 series, but you can change the position by shimming. You will change the position by placing vinyl on the upright on the capping station where the print head carriage contacts it. You cut 6 to 8 pieces of vinyl in the shape of the upright, stacking them on top of each other. Then clean the upright with alcohol and stick the vinyl "shim" stack on the upright. Repeat steps 1-5 and add or subtract vinyl "shims" as necessary. This should solve your issue. I have fixed a number of Mimaki printers with air leaks at the cap-head interface by this method. You will have to periodically replace the shims, but this should do the trick.
Another thing that can help is to insure the print heads are all pushed to the left side of the individual head mounting plates. This will require removing the heads. This insures the heads are all properly spaced relative to each other in the head carriage. You might check this first, and if you still have an issue, try the shim technique.