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ink channel not printing

Posted: Thu Dec 14, 2017 4:41 pm
by casementsigns
On my EJ-640 one of the ink channels (black) on one of the heads was not printing at all. Everything else fine. I suspected a stuck damper so changed the offending one for a new (original) damper. I did a choke clean after changing it. The result is I now have one of the yellow channels not printing also! So am I right to now suspect air in the line (which also got into the yellow line while working on the machine)?

If so, what's the best procedure? Use a syringe to draw ink through? And through what - the head, damper, ink line, etc?

Or could it be something else entirely?

Thanks in advance!

Re: ink channel not printing

Posted: Thu Dec 14, 2017 6:30 pm
by mrtn
If there’s still air in the line after choke cleaning there’s something wrong in the vacuum system, a leak or a crack.

Avoid choke cleaning at all cost. If possible, don’t do it.

Re: ink channel not printing

Posted: Tue Feb 06, 2018 3:33 pm
by casementsigns
ok, I am trying to revisit this problem now! The machine still prints (and works every day) but obviously the quality is not 100%! Attached is the test print. The missing yellow channel sorted itself out, so I'm just left with the original missing cyan channel still.

What might be causing this? Air in the line? Did I need to draw ink through manually with a syringe after changing the damper? If I need to draw ink through to clear the air bubble, where do I attach the syringe?

Or is it something else, cap top maybe?

If all else fails I will call an engineer in, but if it's something I can fix myself I always prefer to do that! Thanks,
IMG_6194.JPG

Re: ink channel not printing

Posted: Tue Feb 06, 2018 3:45 pm
by mrtn
I suggest you contact the local tech support. I wouldn't mess with print heads myself if I were you.