Designjet 500 has started printing bands on prints NOTHING seems to fix this problem.

[RHOPKINS]

I have tried updating drivers, updated firmware printed with and without spooling.
I am wondering if I have a ram issue? Tried with and without the GL/2 card.
New printheads, new ink cartridges running Windows 10 on one machine and
Windows 11 on another. Get the same results in both.
This printer had been printing fine on both computers. Any help would be appreciated.
DSC_4458.jpg

[Lance15]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Banding is typically a printhead problem.

How do internal prints look?

Is the encoder strip clean?

[blackcat4866]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Are those bands crossfeed ... or in the feed direction?

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

[QUOTE=Lance15;2158880]Banding is typically a printhead problem.

The internal prints are perfect. All new printheads, and it passes all calibrations. Encoder strip is clean. I talked to HP today and they said it sounded like the feed roller encoder sensor was dirty. So I have taken the left side panel off, but I can't figure out how to get to the sensor encoder wheel. I got the cover to the sensor off easily but I have taken everything I can off to get to it but have been unsuccessful. There are no Youtubes for the disassembly to this encoder. I have found a lot of dust and some spiderwebs thus far so I am pretty confident that the sensor wheel is dirty. I just don't know what to disassemble next.

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Are those bands crossfeed ... or in the feed direction?

The bands are completely across the print horizontally. The printer prints perfectly for about 6 inches then does one band, and starts printing perfectly for about 5 or 6 inches then another band, then prints perfectly. On a 24x30 print it will do 4 bands. I done multiple prints and the bands will like up perfectly in the same sequence even if you change sizes. I talked with HP and they said it sounds like the drive feed encoder is dirty. I have removed the left side cover but have not been able to get to the encoder on the left side of the printer. I just can't see how to get to it to clean. I got a small cover off that shows part of the encoder but the wheel I can't get to. It is dusty inside the area of the encoder.

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

The bands are crossfeed. See attached photo. ThanksDSC_4457.jpg

[D Hook]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

If your internal prints look fine I would suspect something other than the encoder wheel. My own experience is that when an encoder wheel gets dirty it can't be read by the sensor and will cause a skip in the print, showing a bright white line where no ink has been laid down. Your banding is light and the image can still be seen, just not as dark. If it was dirty to the point of causing a skip, that would show up in the test print as well as the print you've posted. When I encountered the problem with a dirty encoder wheel, any print made would show the white line where there should've been ink, including the demo prints from the printer itself. Mine had actually gotten dirty with grease from another component that was over greased at the factory and slowly leaked onto the encoder wheel. Once cleaned off it went back to printing normally.

As far as cleaning the encoder wheel, if you can get a canned air nozzle close to it, that should be about all you need to get the dust off.

As I said, this is only my experience, limited as it is. Some others I'm sure will chime in with other possible causes/solutions. But I don't think there's a problem with the printer itself.

Maybe a memory issue?

I guess I would start looking at the program you're using to produce the image. Does this banding show on everything you send to the printer using this program? Is this an Adobe product? Does the banding show up even on text, like the test print page? Do PDF versions of this image print ok? Does changing the paper type make any difference?

Be interesting to know the solution to this.

[Gift]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Did you check against another paper roll / sheet?

[blackcat4866]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

... I guess I would start looking at the program you're using to produce the image. Does this banding show on everything you send to the printer using this program? Is this an Adobe product? Does the banding show up even on text, like the test print page? Do PDF versions of this image print ok? Does changing the paper type make any difference?

Be interesting to know the solution to this.

That was my thought, too. Try other applications to see which ones are affected. That 6" interval might just be resistance from the paper rubbing spindles. That interval would imply a paper roll diameter of 1.90" ... which is impossible. The core is either 2 3/32" or 3 3/32" =^..^=

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Hello D Hook;
Well I attempted to clean the the encoder wheel, but I could not get to it to really see if it was dirty. I sprayed compressed air in a crack that I thought was the encoder. I took half the machine apart but could not get to the encoder. I have not tried printing a long document I will do that tomorrow. Update: I put it back together after hitting it with air, and now I have clear white spaces. I have made matters worse. I have the printer rigged where I can operate it without the cover on it. You can see the carriage skip (do a double line feed) ever so often. I have attached the latest photo. I am using Adobe Photoshop 22.3. I believe either the encoder is now really dirty or it may be a bad stepper motor. I thought I had worked on some pretty bad boys, but a designjet wins the prize. I don't know what you have to do to get to the blasted motor or encoder. I gutted it pretty good. The service manual is worthless other than part numbers, wish I had some exploded views. Oh, I will share with you if I make any headway.image-2.jpg

\

If your internal prints look fine I would suspect something other than the encoder wheel. My own experience is that when an encoder wheel gets dirty it can't be read by the sensor and will cause a skip in the print, showing a bright white line where no ink has been laid down. Your banding is light and the image can still be seen, just not as dark. If it was dirty to the point of causing a skip, that would show up in the test print as well as the print you've posted. When I encountered the problem with a dirty encoder wheel, any print made would show the white line where there should've been ink, including the demo prints from the printer itself. Mine had actually gotten dirty with grease from another component that was over greased at the factory and slowly leaked onto the encoder wheel. Once cleaned off it went back to printing normally.

As far as cleaning the encoder wheel, if you can get a canned air nozzle close to it, that should be about all you need to get the dust off.

As I said, this is only my experience, limited as it is. Some others I'm sure will chime in with other possible causes/solutions. But I don't think there's a problem with the printer itself.

Maybe a memory issue?

I guess I would start looking at the program you're using to produce the image. Does this banding show on everything you send to the printer using this program? Is this an Adobe product? Does the banding show up even on text, like the test print page? Do PDF versions of this image print ok? Does changing the paper type make any difference?

Be interesting to know the solution to this.

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Did you check against another paper roll / sheet?

Yes I bought a new HP roll of paper 2 days ago and it made no difference.

[RHOPKINS]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

That was my thought, too. Try other applications to see which ones are affected. That 6" interval might just be resistance from the paper rubbing spindles. That interval would imply a paper roll diameter of 1.90" ... which is impossible. The core is either 2 3/32" or 3 3/32" =^..^=

Blackcat;

Yes it is a 2 inch core. Any suggestions on how to disassemble the monster to get to the stepper motor and encoder? If you read my previous thread I tried cleaning through a small opening to the encoder, and when I put it back together I now have clean white lines. I could also see the feed motor making the jumps. I have the printer rigged so I can operate it with all the covers off. Here is my latest print. I am going to print some text data and see if it skips on it.image-2.jpg

[Gift]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

That new sample looks worse than the first one, now there's definetly ink missing but I think the geometry is OK or is the image somewhat stretched in the brighter areas? How does it look under high magnification? Is there any difference if you change quality/dpi settings?

[D Hook]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Please post up an image of a demo print you've recently printed from the printer's front panel. This will confirm if the printer is at fault or the program you're using. If the demo prints out fine, then the printer is working as expected and you can focus efforts elsewhere before tearing the machine apart or getting the parts cannon loaded.

[D Hook]

Re: Designjet 500 has started printing bands on prints NOTHING seems to fix this prob

Here's a link to the service manual posted up by LPS Computers: https://cdn.shopify.com/s/files/1/10...84334271461826

On page 8-90 they show the encoder disk and how to get to it. It's actually in the section on Drive Roller and some parts they list to remove may not need to be removed. I don't have a machine in front of me so can't make that call.