Panel Video Quality - Static / Artifacting

[mprigge]

Hi Everyone!

I have an official 7" touch screen for my Pi 3B which has some video quality problems:

https://youtu.be/XKevqDokCHw

Does anyone recognize this and/or know which component may be to blame? I have bought another screen and will likely return this one as defective, but I'm curious which component might be the problem and wonder whether this is a common problem for these panels.

It's notable that the Pi is booted into IoT Core here, but that the static/artifacting is present even in the rainbow test pattern that is written to the panel when it first powers on (it's short, so it's hard to catch on video while also plugging the thing in). I'm not sure if that pattern comes from the panel itself or the control board, so I'm not sure where the problem actually lies.

- Matt

[mprigge]

Well, I've gotten a replacement and this one has the exact same problem (except worse somehow). Is there a chance the Pi itself could be the source of the problem?

[DougieLawson]

Have you pulled the green and yellow wires off? If not, then do that.

[mprigge]

Yes - never installed them as I don't think they're required for the 3B. I only had the GND/+5V leads attached. I've tried several different combinations of powering the boards -- using the same 2.5A power supply with the red/black leads in place as well as using different power supplies for each board and using the USB OUT -> USB IN jumper. None of that seems to make any difference in terms of the display issue. All of them successfully power the RPi, though.

[DougieLawson]

OK. So it's either a faulty ribbon cable, a faulty connector (one end or the other), a good connector with a badly fitted cable (one end or the other) or a broken RPi.

I'd start by visually inspecting the solder joint between the connector and the RPi board. You may be able to reflow it to make it better if any of the connector pins are showing a dry joint.

[mprigge]

The solder joints look pretty good, but the DSI header is on just a little bit crooked:


(embiggened)

It doesn't seem like that'd cause a problem all on its own, but I'll round up another RPi 3B and see if that solves the problem (unfortunately, I don't have a multimeter handy to actually test it). I have tried complete replacements off all of the other components, so that's really the only thing left.

Thanks for your suggestions!

[mprigge]

Replacement RPi 3B fixed the problem. Chalking it up to a bad DSI header.

Thanks for your help!