Latitude E6430 audio controller issue - Where is the controller chip located?

Dear All,

I have an E6430, with Windows 10.

The sound card worked fine until last night. I unplugged a USB headset and the internal sound card is no longer reactivated. This is not a software or driver error, as the internal sound card has disappeared from the device manager and the original sound card driver cannot be installed again because it cannot find a compatible device.

I tried to install a new clean Windows7 and Windows10 on another hard drive, the sound card is not there either, nor as an not installed device.

The speaker does not beep during the Dell Bios Diagnostics and under DOS test programs. The internal sound chip is probably broken.

I also reset the BIOS and also removed the cmos battery for a few hours. No results.

Question: Where is the main audio control chip located? Is it on the big motherboard or is it on the small separately replaceable PCB, where you can also find the jack, VGA, LAN connectors?

What do I have to order to change? The complete motherboard or only the small PCB with the jack connector?

Thanks,

Attila