• I want to thank all the members that have upgraded your accounts. I truly appreciate your support of the site monetarily. Supporting the site keeps this site up and running as a lot of work daily goes on behind the scenes. Click to Support Signs101 ...

Need Help MUTOH XpertJet 661UF is driving me crazy. Need help replacing Valve Head Assy!


New Member
Hello! I apologize in advance for how long this post is; I just want to include as much info as may be helpful. SO, I've been an engraver for about 15 years. I also run multiple lasers, screenprint, make photopolymer signs, rubber stamps, etc-basically every single thing but printing. About a year ago though, our shop acquired a Mutoh UV printer, and I ended up being one of the only ones trained on it, and am now the only one left that even knows how to turn it on. I've spent the past year learning my way around it and its many quirks...our dealer has been FAR less than helpful, therefore when problems arise, I either have to work away at it until I figure it (or a good workaround) out, or look it up online. And though it is slowly growing, there is still quite a lack of internet chatter/knowledge about this guy. It wasn't until recently I started seeing actual posts about it on here. I've loved this community for years and years - you guys have gotten me through a lot of weird issues - so I re-signed up JUST to try to get a little help with this printer.

Okay SO among the myriad of issues I've run into, my biggest one right now is simply the color white. If I clean everything up, give it a nice soak, and hop on my left foot three times (jk), it'll eventually give me a nice clean nozzle test. However, the more I print the more the white nozzle clogs right back up and halfway through the day I have to just stop and give in to the fact that she's not doing any more for the day, and requires a soak and a rest. This has almost always been an issue, but now it's simply debilitating, considering I'm supposed to be printing 300 colored plates with a full white back. Again, speaking to our dealer was pretty useless, so after reading up everything I could about printer maintenance in general, I found out that some things naturally need replacing at least annually, ie head cap, dampers, etc. I requested they sent me a new maintenance box and dampers. I received a new Head Cap Assembly (the cap and its tubes, not a full maint box) and a Valve Head Assembly. I was able to switch out the cap fairly easily (again, I don't know printers too well but I DO know about taking things apart, figuring them out, and putting them back together) but I hesitate about the other piece. I don't know where to look in the machine, nor how to even properly flush dampers. I can't seem to find any kind of tech maintenance manual specifically for this printer anywhere online, and the only things they gave to me with the machine were for daily maintenance. Fearing that it might possibly involve messing with the printer head, I'm far too scared to just do my usual hands-on investigation, relying on similar-but-not-the-same printer help videos.

Has anyone with a UV Mutoh done this before? Or maybe there's a video I missed? A manual or a post maybe? Should I be intimidated or is it as easy as some of you make it out to be? :)
I can't even be sure that this will fix my problem, but it seems to be the best place to start. Aside from the constant clogging of white there also always seemed to be a major excess of ink going into the sponge...so much so that it's natural habit for me at this point to open 'er up every few plates and dab it dry (along with lightly dabbing off any small fibers/whatever it was that would appear on the cap), lest my work become splattered with random ink. I also have issues getting the same shade of a color to come out each time, even when I'm just re-ripping the same file. ESPECIALLY if it's a day or more later. I'd decided that most of that was the white fading and therefore changing the hue on a CMYK+W print, but it's not ALWAYS a white-backed print, so there's likely something else I have to address after the white. I've also had to remove half-full cartridges of ink bc the machine INSISTED it was empty. What do you guys think?

Note: I have changed the wiper, the sponge/pad, and the inks are not expired (some WERE, but not white-we use way too much of it way too frequently). The room it's in is not necessarily ideal temp or humidity, which I do plan on addressing in the near future, but it's not horrible either.