Mutoh ValueJet 1638UH – Printhead side guard came off + nozzle plate edge lifting

[brammekeuh]

Hi everyone,

I’m working with a Mutoh ValueJet 1638UH UV printer and ran into a problem with one of the printheads. The small protective metal guard (“head guard” / “side protector”) on the side of the printhead came loose. Since that happened, I also noticed that the edge of the nozzle surface on that side seems to be lifting slightly.

At the moment it looks like:

• The guard is no longer properly fixed.
• Only the side edge of the nozzle plate is lifting, not the whole surface.
• Printing still works, but I’m worried this will get worse or cause permanent damage.

My questions:

1. Is it possible to re-attach or replace just that small protective guard?
2. If the nozzle plate edge is lifting, does that always mean the head is near the end of its life?
3. Has anyone replaced a printhead on the 1638UH themselves, and if so, what’s the best way to do the alignment afterwards (without official Mutoh service software)?

I’d appreciate any advice, part numbers for the guard or head assembly, or tips on whether this is still safe to use or if I should be planning for a full head replacement.

Thanks in advance!

 

[Solventinkjet]

If the metal guard is damaged or bent, putting it back on might just cause more problems. I've taken the metal off of a used on e and replaced it before though. There's just 4 little screws that hold it on. If you can do that, that's the best solution. That guard not only guards the head surface from head strikes, but it also helps discharge static build up around the head. Just note that the 4 screws that hold it on also hold the manifold on the head. It doesn't pop off easily however but just be aware that when the screws are out, be relatively gentle with the head.

The fact that the head surface is slightly detached is a sign that the head could fail sooner rather than later. You might get lucky though. If you start seeing colors mixing in the nozzle checks, that's a sign it's close to the end.

All of the head alignments are done on the printer itself and no software is needed. You just need to get into service mode by powering the printer on while holding the up, right, and down keys.

The official part number for that head is DH-40866 but any DX7 head will do. There is no part number for the guard because it's not an official part. You can only find it used.

 

[brammekeuh]

Thanks a lot for the detailed reply, that helps me a lot!


I do have some experience with maintenance on this machine (for example, I’ve already replaced dampers before), but I’ve never actually replaced a printhead myself. That’s why I’m a bit cautious.


Do you know if replacing the head itself is considered much more difficult than replacing dampers?


Also, could you maybe outline the main steps for doing the alignment once the new head is installed? I understand from your message that all alignments can be done directly on the printer itself in service mode (holding up + right + down on power-on). If you have a quick step-by-step of the alignment sequence (bi-directional, interlacing, head slant, etc.), that would be really valuable.


Basically I’d like to know:

1. Is it manageable for someone with damper replacement experience to replace the head?
2. What are the critical things I must watch out for when removing/attaching the new head?
3. Could you share a simplified procedure for the alignment menu sequence after installation?

Any tips or “watch out for this” advice would be highly appreciated!


Also, to clarify the current situation: the nozzle plate on this head is actually coming loose on one side. Because of that, it sometimes scrapes against the media and causes visible damage to the prints. In the meantime, before I manage to get a replacement head, is it at all possible (or recommended) to remove the loose nozzle plate entirely to prevent it from scratching the media? Or would that just make things worse?



Thanks again for your help.

 

[Solventinkjet]

I've personally helped 1000s of people install their own printheads. In my experience, most people can handle it. The main thing is to be patient and not try to rush through it all. Avoid spilling ink on any of the electronics and make sure to unplug the main power cable from the printer, hit the power button, and wait about 15 minutes before doing anything. That will protect you from causing any electrical damage like popped fuses etc. Other than that, the process of actually installing the head is basically taking the dampers out, removing the old head, and putting the new one in. I usually install the head cables on the new head before installing it because they are hard to install once the head is in position.

As far as alignments go, there are physical and electrical ones. A lot of the time you get lucky and don't need to do the physical ones but always check anyway. The printer will print out a pattern and you adjust it based on how it looks. On this machine they make it easy and they just use levers to do the adjustment. You adjust it, then print another pattern and keep going until it looks good. The electronic ones are similar but instead of physically adjusting it, you input numbers into the printer that tell it which pattern looks good. It's hard to explain without going into a ton of detail but those are the basics. It will help you much better to get a hand on the tech manual. If you ask for it her eon the forum, someone usually will have it. It goes through the steps for each alignment. One note on alignments, you can skip the ones that are labeled as Unidirectional. Those should only be off if the printhead is completely malfunctioning in which case the alignment is the least of your worries.

Taking the nozzle plate off will essentially remove the nozzles and you won't be able to print anymore. So you're probably looking at a new head sooner rather than later if it's physically touching the media.

 

[brammekeuh]

Thank you for the advice.

If I remove remove the nozzle plate, will it drop ink? So is it possible to print with one head?

Thank you