new head, black ink starvation

[stevenjowens]

I posted in another thread about two new print heads. I haven't actually installed those yet, because I'm seeing some ink starvation in one the other two printheads, which were already professionally replaced by a skilled mimaki tech.

We the black and magenta heads replaced, but the black seems to be starving for ink.

There's plenty of ink in the cartridge.
I manually pulled ink with a a hypo and we did not see any bubbles or other signs of a bad damper or ink line.
If I let it sit while powered up, the black ink just slowly drops out of the test prints.
If I do a normal or soft clean, it comes back.
If I print a regular image (photo of a parrot), it drops out.
If I print a solid black bar, it doesn't drop out.

Here are photos of the tests and test patterns:

http://www.darksleep.com/mimaki_black_ink_starvation/

 

[TBFL]

Perhaps your capping tops are dirty and clogging your heads when they rest on them. have you tried replacing the caps?

 

[BigfishDM]

Have you tried doing a hard clean?

 

[inkjet frank]

Print head black channel

Hello,

sounds like it's still a good print head you may just need to flush It.

Did you also check the pump, making sure it pumps properly? Pull from the pump to see what happens.

also check capping position.

after tryi these two things, if it still drop out, flush the head. I guarantee you it will come back. I have seen problem like this numously times on Mimaki printers. It's not a big issue.

I posted in another thread about two new print heads. I haven't actually installed those yet, because I'm seeing some ink starvation in one the other two printheads, which were already professionally replaced by a skilled mimaki tech.

We the black and magenta heads replaced, but the black seems to be starving for ink.

There's plenty of ink in the cartridge.
I manually pulled ink with a a hypo and we did not see any bubbles or other signs of a bad damper or ink line.
If I let it sit while powered up, the black ink just slowly drops out of the test prints.
If I do a normal or soft clean, it comes back.
If I print a regular image (photo of a parrot), it drops out.
If I print a solid black bar, it doesn't drop out.

Here are photos of the tests and test patterns:

http://www.darksleep.com/mimaki_black_ink_starvation/

 

[stevenjowens]

Frank,

Hello,

sounds like it's still a good print head you may just need to flush It.

Did you also check the pump, making sure it pumps properly? Pull from the pump to see what happens.

also check capping position.

after tryi these two things, if it still drop out, flush the head. I guarantee you it will come back. I have seen problem like this numously times on Mimaki printers. It's not a big issue.

Thank you.

By flushing the head, do you mean filling a syringe with cleaning fluid, pulling the damper off the back of the printhead, plugging in the syringe where the damper attaches, and letting it (gently!) drip through the head? I have not yet done that, but it's a brand new black head. I can try it, though I'm curious why that would help with ink starvation.

If you mean something else, what do you mean?

I'm not clear on what you mean by "pull from the pump". If you mean plugging a syringe into the end of the waste line and using it to pull ink through, I did that. I didn't get any bubbles or air in the waste line, which I would assume means that there was no air entering at the capping station, and therefore the capping station seal is good.

The capping position looks good as far as I can tell just by eyeballing it. I'm not sure that I'd be able to see anything subtle - whose idea was it to use black rubber on black plastic and put deep inside a machine where you can't get a good look at it, argh...

 

[boxerbay]

somehow somewhere you have ink in the line. that is what happens when you have good print then 6" into it drops. you have an air bubble floating near the head. when you begin to print it get pulled down into the nozzle area and then you get banding. we see this all the time with our flat beds and purging through the vent tubes resolves the problem.