Switch screen turns off randomly, but console is still on

Insomniac · June 7, 2022, 7:55am

So removed, cleaned, reballed and fitted this all over again last night and it seems to be working
At least I got a list of wifi points and bluetooth is working again. Will need some proper testing to see if the orange screen has returned etc. If there are still issues I will return, but otherwise it’s looking good!

Severence · June 7, 2022, 2:36pm

Nice one. Glad you got it sorted

Insomniac · July 31, 2022, 2:27pm

ahh damnit. So, I finally got round to giving this a good proper test, and everything was working well until I got it connected to the Wifi again. Wifi itself worked fine (as did bluetooth), I was able to install the latest updates and get the updates for a game no problem (while it was docked). But now it is back to a combination of the original issues. The backlight turns off shortly after the screen is turned on, and if you keep turning it on and off again it will eventually orange screen. I seems unlikely at this point to be something with the wifi chip itself, what’s next to poke at? backlight driver?

Severence · August 1, 2022, 11:20am

Shame,

Yeah it’s less likely to be the wifi IC at this point. Yeah, I’d go ahead a replace the backlight driver as a matter of course, failing that the 8316 and failing that too, I’d swap the LCD connector itself…and it might also be worth verifying this board in another LCD/assembly too incase for whatever reason the LCD has issues.

failing all of the above there’s not many places left to point the finger other than at the SoC… the PMIC can in very rare cirumstances cause an orange screen (afair) but it’s unlikely.

Insomniac · May 21, 2023, 11:21am

It has been a while, but I have finally got round to swapping the backlight IC. It went well, I still have backlight, but it didnt fix the issue.

That said, I haven’t seen the orange screen in a while, currently I get an error message after turning turning the screen back on from sleep, but only with wifi turned on and connected.
I will do some more testing to see if that is the only symptom now.

I have already got it in my test case, so its not an issue with the LCD itself.

I kinda suspect it has to be whatever is supplying power to the backlight and wifi chip, which I guess is the main PMIC?

Severence · May 21, 2023, 12:29pm

I see - this intermittent behaviour is further reinforcing the SoC being the issue given all your other steps ruling stuff out. Wifi I/O issue SoC side would be my guess. The only way to truly rule this out would be to swap the SoC and EMMC over to a known good donor board and see if the problem travels across.

Sorry I haven’t documented what any of the source rails are as I usually just buzz this al out when I’m working on them so I could be remembering wrong but I think backlight VIN is SYS (but you’ll wanna check this) so don’t imagine that’s your issue. WIFI IC VIN is 3V3PDR and/or SYS too as far as I remember (though you’ll wanna double check this too) and it generates it’s other rails internally. After you’ve verified these rails I guess you could monitor the voltage and see if they fluctuate at all - if they don’t then that’s probably not your issue either.