I have a Raspberry Pi 5 as my Linux box. Debian / KDE, all updates applied as of this morning. I’m using a Samsung 65" 4k LCD as my monitor, with a Yamaha Aventage receiver in between, acting as a source / sound manager.
I wanted to get 7.1 sound working so I resolved to sit on the couch and have an AI walk me through the steps needed to solve all the issues. However once I got started I realized that the distance and the lousy rendering of text on the screen (don’t know if its Firefox, Debian, KDE, the Pi, or whatever) meant I’d have to sit on the floor 3 feet from the display to do my work.
Since fixing text sizing on my iMac is as easy as changing to a lower resolution, I figured I’d do the same with the Pi. What a huge mistake.
I looked in the Displays control and found it was set to 4K, so I dropped it down to 1080p, 16:9. The display blanked out and then the TV reported no source was connected. I power cycled the Pi, watched the thing go through POST and load the OS, then the login screen came up with the text in tiny 2pt type. I got a foot away so I could read it, and then logged in. Spinning Debian logo, the display went to black, and then the Samsung told me “no source connected”.
Nothing brings back my desktop. I hope someone can tell me how to get around this little speed bump so I can go back to getting some use out of it.
This usually happens when the Pi switches to a display mode your TV or receiver doesn’t support. Power off the Pi, put the SD card in another computer, and edit config.txt on the boot partition to force a safe mode like 1080p. After saving, put the card back and boot again. If there’s still no picture, connect the Pi directly to the TV instead of going through the receiver, then use display scaling in KDE rather than changing resolution.
I don’t normally respond to bots but in this case I will, because I don’t want anyone reading this thread to be misinformed. I’m a living person with decades of experience in the audio/video industry, but I’m a Linux rookie. Based on “sanjay210” posts in other threads, I believe he’s an unqualified person posting generic AI-generated advice, most of which ignores helpful responses that actually solve the issue, weeks or months earlier.
Here’s where he’s sending us on the wrong track:
he says this was caused by switching “to a display mode your TV or receiver doesn’t support”. That would make sense if I selected 4k120Hz while the Pi 5 was hooked to a 10 year old TV and receiver that didn’t support that mode, but I switched the Pi 5 to 1080p60, which I’m fairly certain that every panel and every AV receiver of the past 10 years can support. Additionally, my Pi 5 as originally configured was running 4k60 through the Yamaha and on to the LG display, and it worked quite well before I tried stepping down the resolution.
he told me to edit config.txt to “force a safe mode like 1080p”. A human would have seen that I ran into this problem by selecting the very mode you suggested.
he assumed I was using an SD card - I’m not, this system is on an NVMe SSD HAT.
In my post I said that after I changed to 1080p and restarted, the Pi 5 booted up and displayed all of its OS loading info on my LG panel perfectly, and it got to the GUI login screen. The issue happened after login - indicating this wasn’t a hardware-level display issue. This was “userland” - something wonky in KDE. Editing at the hardware level isn’t going to fix that.
If I’d gone to the trouble of pulling my SSD out and attaching it to my iMac to edit config.txt, would the iMac have been able to read the Linux file system?
Even if I succeeded in editing config.txt and re-installing the SSD and starting the Pi 5 without any problems, KDE overrides config.txt when it launches, so his edit would have been a huge waste of time.
the only piece of useful advice he offered was that display scaling in KDE should be used, not a resolution change.
For those following along in this thread, I ultimately resolved this issue by doing the following:
Power cycle the Pi
At the login screen :
Press Ctrl + Alt + F2 (switches to text console/TTY2).
Login with your username/password.
Then enter the following:
rm -rf ~/.config/plasma* ~/.local/share/kscreen/ ~/.cache/*
sudo systemctl restart sddm
If needed: Ctrl + Alt + F1 or F7 (returns to graphical login).
Login again—desktop should load at safe resolution (e.g., 1080p fallback).
Reconfigure display in System Settings > Display.
I was referring to my poorly-written notes from when I fixed this a few days ago, so if there’s any error in the rm command above, thats on me.
Thanks for joining me on this. I get what you’re saying. I think posting solid info won’t be used to train their bot/agents, because that information is already available on many forums, yet they don’t use that. And by the time they join a thread and post their “solution”, the OP has been helped and the thread has good, relevant info, not this generic out-of-date stuff.
Now what I’m not going to get into in a public-facing thread is how I noticed these were AI agents. Thats something that they WILL learn from. You spotted it, so did I, and I’m having discussions with people behind the scenes where we exchange notes on this.
I’ve flagged numerous messages for removal, and sent many notes to the admins pointing these aberrations out so they can investigate it fully, but I’ve never gotten a response. I think it’s time to put a big spotlight on them anytime they surface, from now on.