Microphone Circuit

[Crinkmeister]

Does anyone have a circuit diagram for the microphone input on a V1 Switch please? Long story short: Fault symptoms were microphone not working and no stereo sound (both earpieces with identical sound). Diagnosed headset ground wire fault. Replaced headset. Also replaced 3.5mm jack socket. Microphone still not working in-game, but I can probe the mic pin with a scope and see that a signal is being generated. So the 2V bias is there and the mic is actually working. Somewhere, the mic signal is getting lost - presumably on the main board. Anyone experienced this before? Mic settings have been checked and are correct.

 

[thesjaakspoiler]

The IC managing the audio is the ALC5639.
It uses a different voltage line/regulator than other chips so a good point to start is to check whether this chip gets voltage

https://gbatemp.net/threads/first-post-switch-not-turning-on-short-near-alc5639.574160/

 

[Crinkmeister]

Thanks thesjaakspoiler. I know the ALC5639 is providing the 2V DC bias for the mic and I used my scope to check that the mic is working by probing the mic band on the jack plug. I assume there is only one trace from mic to the ALC5639 and that the audio signal is AC coupled into one of the analogue inputs, so why it is not working is evading me!