Hp8000 banding

[ae101]

Hi lads, having a problem with our hp8000 for the last little while. When printing, we get banging in the darker shades and printing solid black is a no go, this print here is at 16 pass, nozzle tests are fine, only a couple of missing nozzles but it used to work fine like that and at 8 pass.

(pic isn't the best but you can see the banding in the print and none in the colour strip)

No amount of cleaning, fill caps or adjusting the feed adjustment fixes it. It will happen regardless of the media type. The print room is kept between 20'c and 24'c, we use sam inks, anybody any ideas for a fix?

 

[papabud]

i would replace a few of your print heads.
even when they test fine i have found they can produce some banding
just replace them and fix your problem

 

[ae101]

i would replace a few of your print heads.
even when they test fine i have found they can produce some banding
just replace them and fix your problem

I was afraid of that answer but printheads are costly, we are looking at getting a new machine sometime this year so i have to keep this one working till then

 

[papabud]

if you use the hp 940 printheads i think they are like 30 bucks a piece on amazon

 

[ae101]

if you use the hp 940 printheads i think they are like 30 bucks a piece on amazon

jays that not a bad price, a i'm only going of what the boss man told me, would there be a lot of configuration to do after changing the print head? would that be a job for an engineer?

 

[papabud]

i think i looked up the wrong printhead number for you. but they still are not bad princed when you think of how much money they produce.
but first you can make sure everything is clean and the printheads are properly aligned
here is a link to your manual that gives full instructions on how to clean your machine and do adjustments.

http://www.hp.com/ctg/Manual/c00843161.pdf

 

[methogod]

We still run a hp 8000s - with sam ink as well... age will show sometimes as banding on longer prints. Before replacing heads we couldnt print 4" without a recovery, no i print 12-18 without issue. Anything more then 1 nozzle per head or if the heads seems to dry out way to fast, and band due to ink starvation i would replace.

1st check your prime assy, they get nasty over time, run "wash print head" and you should have ink on all 6 prime assy drain tubes after 1 or 2 cycles, if you have to run 3 or 4, would start there.

2nd Make sure your Caping Units (Q6670-60065) are not old, they should be less then 2 years old - otherwise I would replace all of them.

We also only run OEM wiper fluid, the SAM INK stuff is fine for cap cleaning and cleaning ink off the platen, but found its not right for cleaning the heads (once you replace you can get another 2-3 years out of it and for sure can sell it for more then your new print heads would cost.
Only other place i would check is your ink dampers, if they look funny - not filling up right, too much air, bulging - would replace as needed (again only OEM dampers)....

I have also found running some OEM ink though the heads can bring dead jets back to life.
We are small company, and I would buy a new Oki version of this machine, just cant justify it right now, we run 10-15 jobs a week, ink is dirt cheap and its reliable....