Designjet Z3200 not reproducing black correctly

New to this forum, but I've been thrust into a position at work where I'm now looking after large format digital printers, with not a huge amount of experience (my background is photographic and retouching).

Anyway, I'm trying to print a black and white image, with a lot of black in it, probably 80% black, 20% light grey and white (its a photographic reproduction of a black lino print).

However when I print it, its printing the black background as a light grey. I've been through everything I can think of and am literally tearing my hair out with this one.

Can anyone help please?

 

Have you done a nozzle check? Have you checked the image in Photoshop to establish whether the blacks really are black?

Does the selected paper match the material that you're printing on? Different materials use a particular blend of MK and PK and the "wrong" black will not give optimum results.

Has an appropriate level of "global ink limit" been selected in the printer utility?

 

Ok, so I think it was a blocked printhead, that print head was still under warranty so they're sending me a replacement, hopefully that will sort it out. I had checked it 2 days before and it seemed ok, but when I did one after trying to get it printed the MK wasn't showing at all.

Yeah I had done the photoshop checks, and the paper was the correct paper.

Hopefully the new printhead HP are sending me will sort it..... Do I need to do anything to stop them getting blocked? It tends to be used quite intensively for a period of time, and then sit idle for a good while.

Global ink limit? Ill look into this. Our IT dept in all their wisdom haven't actually given me access to the print utility.