Need Help Mimaki Ucjv 300 firing nozzles all the time

[pottifar84]

Hey all.
I just bought a used Ucjv 300. Full of error messages when I bought it, but getting there now. Replaced both subtanks, 2-3way air valve, 4 of the ink valves and black ink line.
It’s now printing pretty good on all colours, but still have a problem with a few nozzles firing all the time. The error is on the second head (LcLmWW) I tried changing the multicolor ribbons from carriage board to print heads, but still the same head misfiring. Also changed the cable from main board to carriage board with the new shielded ones. From the nozzle recovery print I can find out which of the nozzles that are constant firing. Is there anyway in the service menu to disable these nozzles? Or any other solutions you can think of? I can’t spend money on a new head right now, so last solution would be to reprogram the printer to a "Ucjv 150" so it only uses one head.

 

[pottifar84]

I tried removing the ribbons to printhead 2 and changed the parameter 66 to 1 just to be able to do a test print, and the stripes disappeared. So it’s not a cleaning issues as I have been told from others

 

[Solventinkjet]

If the new cables didn't fix it, it's probably the head unfortunately.

 

[Smoke_Jaguar]

If it seems to be a random channel(s) that are dripping, it could be an air leak in the head itself causing the head to leak ink while printing. If you haven't already check and see if an air purge clears it up. In certain cases, it can also be a small leak in the damper, not a cheap part, but if it fixes the issue without needing a head, worth it.

If the channels leaking seem to be at the same point consistently, head/electrical is my guess.

 

[pottifar84]

Electrical issues/head is where my thoughts are going too. I already changed both the sub tanks. I don’t think there is any dampers on the ucjv? I will try to disconnect and reconnect all the ribbons again today. Look for any ink marks or broken parts. Worst case I will just clean the ink lines and head. The try to reprogram it to a "150" so it only uses 1 head. After all I just paid 450$ for the machine

 

[Smoke_Jaguar]

Subtanks are used instead of dampers as they can handle the thicker ink and support vacuum/pressure loading. Can try turning on nozzle recovery to disable the specific nozzles and see if that cuts power those nozzles.

 

[dudeinthemoon]

Checkyour HDC pcb, if you're sure the printhead and its cables are fine, check the other side of the HDC pcb, at the other side of the connectors on HDC board you'll see small elements marked as Lxx (xx - number), these are coils they should have continuity, and visually check all small elements near the connector pins, sometimes soldering becomes fragile and if the pcb was removed for something it could be damaged. Your problem it is 100% connection issue and if both heads has no printing issues then repair or replace HDC pcb.
You can check the second head by just connecting it to the first head port, you can leave the first head disconnected for testing, there is no need to change parameters UCJV300 can boot up with only one head connected only the nozzle test will look weird, but you should see no lines if head and cable are fine

 

[pottifar84]

Checkyour HDC pcb, if you're sure the printhead and its cables are fine, check the other side of the HDC pcb, at the other side of the connectors on HDC board you'll see small elements marked as Lxx (xx - number), these are coils they should have continuity, and visually check all small elements near the connector pins, sometimes soldering becomes fragile and if the pcb was removed for something it could be damaged. Your problem it is 100% connection issue and if both heads has no printing issues then repair or replace HDC pcb.
You can check the second head by just connecting it to the first head port, you can leave the first head disconnected for testing, there is no need to change parameters UCJV300 can boot up with only one head connected only the nozzle test will look weird, but you should see no lines if head and cable are fine

Unfortunately everything points at the second head now. I tried as you said. Cables from second head was to short, but I connected the first head to the ports of the second head, and it printed just fine without any lines. So doesn’t look like pcb problems either. So will continue with plan b and convert it to a "ucjv150" and only use the one head that is working fine.
Anyone her done this before?
It should be possible but just need to figure out how to