Reviving a UJF-6042 (MK1), No Ink From Heads

[Smoke_Jaguar]

After spending a few long days working on the scrapped UJF6042 I got a while back, I am still having issues getting any ink from the heads. I've flushed the lines with ethyl acetate (LF-200's primary chemical), replaced the dampers, flushed the heads directly and gotten great nozzle flow on what appears to be all channels (waterfall check) and gotten all error codes cleared. All caps engage the heads properly, the suction nozzle has been replaced and I have the bed as high as it can go without tripping the work high alarm (since I know even a few extra mm can lead to a nozzle check looking like a puff of color). I know there is a deflate process, but all checking seems to indicate there is no air left in the lines.

The printer was left sitting with LH-100 (CMYK Primer Primer WW) for a couple of years, but was in working shape when shut down. Not sure if there is massive degradation of lines. The ink I got out was pretty bloody thick and I know the cartridge needles are replaceable. Is this possibly a flow issue? Heads seem to be talking to their control board as I used a Ricoh Gen4 head simulator to pass error codes on to the slider board, and it triggered proper errors on the display. I am using new (cheap knockoff) inks, and am stumped. Not sure if there is a case that can cause all 4 heads (8 channels) to die. But I would love to get this unit up and running for more crazy ink experiments.

 

[netsol]

i have never done a machine with ricoh heads, but, same principles should apply

did you consider that your flush/reverse flush may have ruptured a membrane or some internal component in the heads? (unlikely, all 8 failing EXACTLY THE SAME WAY, though)

damaged ribbon cable, blowing a fuse for the print head drivers? typically 41 volts on the rolands with dx4 head

perhaps it is possible to flush and allow flow through the ricoh heads, WITHOUT actually freeing up the "moving parts" inside the head (the part that FIRES)?

is there an internal bypass in the ricoh heads that allows flow WITHOUT clearing the part that fires?

FINALLY, and more to the point, i am always skeptical of flushing clogged heads with the ink's active ingredient. (ink with no pigment).

we always use a bit of acetone or isopropyl (whatever will wipe ink off a completed print job [this is basically what you are doing, inside the print head] and enough of a buffering agent to keep the clog from solidifying again, when the acetone evaporates, before you flush the whole mess out.

so, i would flush ONE HEAD AGAIN, with a bit of acetone, (not too much) in your flush SOLUTION you previously used. chase with alcohol, then compressed air LOW PRESSURE, lets see if you can get one head actually firing.

if it would help, i can loan you our chinese knockoff printhead doctor,
you could also contact vlad, who developed the printhead doctor, at his office in canada.
he sells around 15 different "recovery solutions" & you can discuss this with HIM, (they give out his cell phone number!). & you would consider sending heds to them for recovery.

i will post contact url from a pc

 

[netsol]

Recovery Fluids

Recovery fluids for Print Head Doctor

digitalsigntech.net

 

[netsol]

i normally include a warning, that you follow my advice about using acetone in your flush AT YOUR OWN RISK (we have had very good results)
the amount you use is critical. too little will not be effective, but, the first time i did this, i used a bit too much acetone & solvent welded the impeller inside one of my pumps. OOPS! too much can also lead to solution leaking out of a hole in the pump or somewhere in the path from damper to waste container

always flush well afterwards

 

[Smoke_Jaguar]

We have a really fancy modded to hell aliexpress 'ultrasonic printhead cleaner' that we added electronic solenoids, timers, a heater and other crap to, so clear on that front. As for the heads, they do have a bypass flow tube on them (2 barbed fittings per channel). The UJF's head assembly actually has a series of 8 capped Luer injection ports (why are these not on the MK2?) that are great for moving ink through the system or doing a quick head flush. That said, it could totally be trapped air inside the head itself causing the issues, in a piezo head, that'd kill its ability to be able to toss ink. I have had a single head pass nozzle check a while back.

As for the cleaning solvent, ethyl acetate is what Mimaki specs (yay SDSs and CAS numbers), and it does a great job on thinning out and busting through UV ink, way better than alcohol. That said, it's rough on plastic panels. Alcohol is an amazing solvent as well, considering it's pretty gentle on most parts, and almost as good as ethyl acetate.

As for the head flushing, I kept the pressure under 2 bar (Ricoh actually has a nice video showing how to flush the heads) and they are really easy to clean. Anajet was selling Gen4 heads for their older DTG printers that came back as warranty, returns, etc, and I bought a half dozen to mess with. Even milled one open and they're so much better than the Epson stuff I was used to.

I guess my next step will be to try and make sure the heads are purged of any air. I might also push some solvent into the dampers to thin out any potentially gelled inks. Might try and see if I can access the feed nozzles from the carts as well. Apparently those can clog as well.