Yellow and black issue on HP L25500

[Dennis422]

Hi gang. I had my printer sitting for about 2 weeks (Vacation and a small shop)
Came back from vacation and had a bunch of screen printing to finish so I ended up not printing for an extra week after vacation.

Tried printing yesterday afternoon and get terrible results. It looks like one of the print heads is dead (3) and that other one is printing yellow/black mix (4).
Any suggestion on how to fix #4?
I did print a few print like that and a test "block" print on the pic. Yellow printed brown instead. I was hoping it will fix itself while printing.
I have one printhead in stock and I have a replacement cartridge (Yellow is down to 52ml).

Also, I got that warning from the printer too.

let me know what do you think.

Thanks in advance

 

[dypinc]

Did you shut it off or leave it on during that time?

 

[Dennis422]

Nope, it was ON.

 

[dypinc]

That is what I figured. The prevailing theory is to let these printers on when not in use, but when I had a L25500 I had nothing but trouble doing that. When I left it run overnight I would come in in the morning and find it powered up, sometime with the fans fired up and sometimes with a error. When I started shouting it off every night I had much less trouble from it especially imaging problems.

Now so far on my L360 I leave it on unless I going to be going for a day or two. Too much chance of power failures in this area.

 

[P Wagner]

You have cross-contamination occurring on one of the K-Y heads, and Y is out on the other one.

For the first issue, I would print a solid Yellow (0,0,100,0) area, in an effort to get the K ink cleared from that channel. For the other head, I would suggest the following:

a) Take a lint-free cloth, and fold it several times to give it more cushion.
b) Take IPA 90%+ and soak the cloth.
c) Remove the printhead, and gently place the nozzle plate onto the cloth, but do not 'wipe' it. You are resting it onto the cloth in clean area(s) in an effort to get the IPA into the nozzles to clear them. You may do this several times, but be sure to use clean areas of the cloth each time. Note that you want to see ink migrating into the cloth in the areas where the printhead has previously rested. Also clean the printhead's plastic areas around the nozzle plate. (see image).
d) Re-Install the printhead and let the machine attempt to do it's printhead alignment calibrations.
e) There are no guarantees that this will work, but it has worked in some situations, and it's worth a shot to keep you printing until you ultimately replace the printhead.

 

[Dennis422]

Thank you.
Will try that later today.

 

[Dennis422]

I was able too get both print heads to fire yellow, but it was still contaminated with black.
I made yellow block and sent it to print.
The attached image is what I got after some time. I lost yellow completely.
The cartridge was low on ink so I replaced it and still after 4-5 feet of printing "nothing" I did not get it to start printing again.
Is there any way to get the ink faster to the printhead in case I bleed the line completely?

I know that on my old Mutoh I was able to get the syringe and pull some ink out.

Thanks

 

[P Wagner]

There are many differences between the ink train on a solvent machine such as your Mutoh, and the HP Latex machines. The solvent machines are gravity-feed while the HP Latex machines are pressurized ink systems.

Is there any ink in the Yellow line? You should be able to see the ink tubes where they attach to the carriage, they are located on the right side of the carriage.

 

[Dennis422]

I got it to print but still have some residue of black in the yellow ink. I had to change one of the printheads. It seems that it stopped ink flow completelly.
Thanks for your help, lets hope the other one will clear up quickly.

BTW, that printhead has a pretty good test plot, not many missing lines in the test print with almost 5000 ml fired