I bought a Raspberry Pi 400 to connect it to my old TV (Telefunken) and make it a smart TV. I installed the latest Raspberry Pi OS, and everything works EXCEPT the sound. I connected the TV by the official Raspberry HDMI cable, and I have the official charger. If I connect the Raspberry Pi to another old Sony TV everything works fine. Also If I connect my laptop (Win 10) to the Telefunken Tv, everything works.
I tried everything I found on the internet, every possible permutations of the options in the config.txt file. (hdmi_group, hdmi_drive=2, etc.) When I go to raspi-config, and enter Audio options, it blinks one, and goes back. So I cannot even get to the Audio options. I use the HDMI 0 port. It seems like a hardware problem in Raspberry Pi.
Do you have any ide what I could try?
vc4-kms-v3dfor the purposes of debugging
tvserviceshould now be able to tell you some details about the HDMI connection that may be useful when trying to figure out why this one TV doesn't work properly