Printer Display Issues with Octoprint

What is the problem?

The Ender 3 Max printer screen looks like a QR code while using Octoprint.
It doesn't affect anything, prints come out great. I use Octoprint on my Windows 10 Chrome browser and never a problem.
I will hear little clicks coming from the printer and notice my display will change to another menu as if I pressed the selection button on it. It will time out and go back to main screen and then do it again from time to time. But what I am really trying to figure out is what causes the massive amount of pixels on my printer screen when printing from Octoprint. The only way to fix it is to wait till the print is done, power off and back on.
I have blocked the USB power wire from my Rasperry Pi 4B 8GB so as to not keep the display on while power is off the printer. My Raspberry is on 24/7 with heat sinks and cooling fan.
As I say, it doesn't affect anything and I never really use the display as I control everything from my browser, but I would like to know what is causing it and how to stop it.

What did you already try to solve it?

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Have you tried running in safe mode?

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Did running in safe mode solve the problem?

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Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!)

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Additional information about your setup

OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible

Ender 3 Max 4.2.2
Marlin 2.0.9.1
Octoprint 1.7.2
Raspberry Pi 4B Rev: 1.4

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Hello @Pauljp !

Backpowering the printer from the Pi can cause various issues with the printer.

You may try this:

Thank you for your quick reply. As mentioned in my 3rd paragraph I have already blocked the 5 volt wire on the USB connection between the Pi and printer so as not to cause any issues.

Oops, I've over seen that.

Then maybe the wiring of the display is way too close to the steppers and their cables.
The high currents can result into EMI that can mess up the display logic.

Now that is a very interesting theory, but perhaps it is coming from the Raspberry module as it is sitting directly under the printer display. Maybe it is giving off EMI. This will be easy to test as I will simply move it to the back of the printer. Thank you for this as I never would have considered that being a possible cause. I will let you know.

You may also have a look on this thread:

Well that seems to be exactly what is happening to mine. I am definitely going to print some isolating washers to put between the display and the frame.
This is fantastic, thank you again for this info. I tried searching prior to posting but I guess I didn't use the right words.
I am going to get into designing it right now and I will let you know.
Thank you once again.

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Here are the isolators that I printed, and although they will significantly reduce the metal to metal contact that may be causing this issue, there is a possibility that the screw threads will still touch the display bracket and conduct to the frame. I tried printing a tiny lip on the screw washers to avoid any contact but there wasn't enough room for this.
Either way I will try it and let you know if it works. If not then I can always just leave the display loose on the side of the printer for further testing.
I will keep you up to date.

Well with the isolating spacer and washers in place I decided to print a PLA temp tower, during the print the display would "chirp" and the display would switch over to another menu. It would then time-out and go back to the home screen. It would continue doing this as indicated in my original post. While it was still printing I removed the 2 screws and placed the display on the table beside the printer so as not to make contact with the frame. The display never acted up again and all printed well for the remainder of the print.
I believe we are on the right track in that there is a secondary ground path resulting in this behavior. I will attempt to print some non-conductive screws to replace the metal ones. That should totally isolate the display bracket from the frame.
I will keep you posted.

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Well I printed an M5-0.8x10mm bolt to replace the metal one in order to be non-conductive.
I will print a second one and install them, then I will test and let everyone know how it is going.
I appreciate everyone's assistance in solving this issue. I could not have done it without you.

I think we have solved the display issue.
Thanks to @Ewald_Ikemann for pointing me in the right direction as I never would have thought to do this to fix the problem.
It seems the display is picking up an erroneous signal through the different ground potentials from the frame of the printer while a Rpi is installed creating abnormal characters and random menu hopping.
So the solution is to isolate the display circuit board from the frame. This can be done in several ways, you could isolate the circuit board itself or isolate the bracket from the frame. I chose the latter.
At first I printed a spacer and a couple of washers but the metal bolts still made contact and the problem persisted. So I printed some M5-0.8x10mm PLA bolts and installed them thus ensuring total isolation between the display bracket and the frame.
I have printed 2 items so far, each about 1.5 hours long and the display has been operating perfectly. I know it has only been 2 prints but prior to this mod it would act up within the first 10 minutes, so I am predicting a success here.

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This may be a dumb question but why not use a non-conductor metal screw?

nevermind, lol

What material comes you to mind?