820-3662 chime but volume icon grayed

[interaptiva]

Hi everyone, I have a macbook pro 820-3662 which emits the chime when powering up but when the system starts up I don't have any audio devices.

I checked the voltages on U6201

PP_3V3 on pins 7-61-85
PP_4V5 on pins 77-129

I noticed that if I plug the headphones into the jack the device detects the audio output on the headphones and the volume icon activates but no sound comes out of the headphones

thank you all

 

[2informaticos]

Ceck all small diodes and coils on the audio connectors page.
Also clean the headphone connector; YouTube videos available.