HP L26500 banding in black

[bigben]

Here is my problem, I've printed 4 12inX12in squares (CMYK) and I have banding in my black square and a little bit in my magenta square. The blue and yellow are fine. All black/yellow and magenta/light magenta printhead are brand new and the cyan as less than 1000ml of use. I've tried head cleaning, hard cleaning, printhead adjustment (automatic and manual) and I still have banding in my black square. Even if I print on vinyl, poster or fabric. If If I print a photo, I don't have banding, even a dark one (like a sunset). If I print a bright blue sky, I have a little of banding, but you see them only at 6in or less.

What to I need to do next? I'm coming short on ideas. Thanks.

Ben

 

[StarSign]

are you printing a gutter with the print?

 

[chafro]

Its probably your black or/and magenta head. Hope its that,, its easy to fix!

 

[bigben]

To answer the questions so far:

• No I don't print gutter. I'm not sure why you ask this question. Can you elaborate?
• the black and magenta printheads are brand new (the black/yellow and magenta/light magenta have less than 60ml and the cyan/light cyan have less than 500ml). The test plot are perfect. Would I still need to change them?

 

[chafro]

I have seen in more than one occasion a good plot but that the head was still making banding in solid colors. I just change head and banding went away.

There really aren’t much more elements if it’s doing it in all your different profiles and medias. Only other factor that i could think of that could affect all you profiles would be your temperature and humidity conditions.

 

[dale911]

I have a L25500 and started to panic a couple days ago when I ran a test print and saw banding, thinking I was going to have to change a virtually new printhead out. I then checked and found that I was running the print too fast. I changed it to a 12 pass and printed again and didn't have any banding. The print was perfect. I would first check to see what quality you are printing before changing the head out with another to rule that out.

 

[MikePro]

"pics, or it never happened"
higher pass rate may eliminate the banding, as I believe that the highest pass rate is used by default in the test prints ...so that's why you don't see it there.

printhead may be new, but there might still be a scratch/blocked nozzles in it from a headstrike and/or old cleaning station.


run a few extra PH cleanings, just to be safe, and print on the highest pass-rate that you can. should be golden.

 

[bigben]

last news: I was doing a head cleaning and at the end, the printer pop me a problem and asking me to shut down the printer. When rebooted, I'm made some test and alignment manually and the problem seem to be solved at 90%. If I take a picture, we can not see the banding. I normaly print all my stuff at 8pass. But If I print at 12pass, everything is ok. At 8pass, the banding is more obvious the first 3-4in, then it blend at the end (12in). I never had any banding problems at 8pass in the past. Do I need to reprofile everything to avoid this?

 

[danno]

I have added an 8 inch test pattern that fires all printheads before I print. It makes sure all heads and heaters are up to a good operating temp before the actual print begins. We also print everything in 10 pass or higher. Nothing else gives us the quality we want to be associated with.

 

[neil_se]

10 pass is my standard, I wouldn't be surprised to see some banding at 8 pass depending on the vinyl.

 

[bigben]

ok, so how do you explain I never had any problem printing in 6pass and 8pass before? At 10-12pass, the printer is very slow.

 

[neil_se]

If you keep a spare Y/K head, just try swapping it in to see if the problem continues.

 

[bigben]

If you keep a spare Y/K head, just try swapping it in to see if the problem continues.

I've swapped k/y and m/lm with the spare i kept and i did not saw the differences. I've made a total of 4 change to swap each head of each color.

 

[chafro]

ok, so how do you explain I never had any problem printing in 6pass and 8pass before? At 10-12pass, the printer is very slow.

Your ambient conditions might have changed? 6-8 pass sounds low for good solid colors in most substrates. We don't print anything under 10 pass, we start losing quality.

If you need more printing time these printers work great leaving them printing unattended at night.

 

[isas]

Your ambient conditions might have changed? 6-8 pass sounds low for good solid colors in most substrates. We don't print anything under 10 pass, we start losing quality.

If you need more printing time these printers work great leaving them printing unattended at night.

We have a brand new L260, brand new everything, get black BANDING at 16 pass! Utterly frustrating

 

[bigben]

We have a brand new L260, brand new everything, get black BANDING at 16 pass! Utterly frustrating

I had the same problem. When you print, check if you see alot of yellow ''sprinkle'' when printing. If you see that, change the 2 black/yellow printhead. I even had a brand new head not firering up properly even if the test plot was very good.

Back to my problem, I did correct my banding problem, mostly. But I'm not 100% satisfied with the solid color it give me. I understand that some of you print at 10pass, but I never had any problem at 8 pass before...

 

[Sign Eagle]

We have an L25500 and had gone thru a lot of in with few head problems, but in the last 2 months we have had to change the cyan head 3 times, one was only in a week. Seems like there must be a bad batch of heads out there.

 

[MikePro]

still, hard to say for sure what your issues may be without actually seeing pictures of the problem & test prints.
sooooooo "pics or it never happened", or get a tech out there to diagnose your issues in-person.

 

[MIMO]

We have an L25500 and had gone thru a lot of in with few head problems, but in the last 2 months we have had to change the cyan head 3 times, one was only in a week. Seems like there must be a bad batch of heads out there.

We've had the same, there are indeed a lot of bad cyan heads being supplied. All you can do is keep a spare or two and return them under warranty.

 

[bigben]

still, hard to say for sure what your issues may be without actually seeing pictures of the problem & test prints.
sooooooo "pics or it never happened", or get a tech out there to diagnose your issues in-person.

Here is the picture at 8pass printed on vinyl. The camera don't show it up verry well. There is more banding at the startup of the print than the end of it (12inX12in square). Oh, and the test prints (test plot) are perfect.