Finally I found enough time to open (again) the laptop.
After I've studied the electronic scheme of MB, I realised that the short that I made was totally wrong.
If I number the pins like this :
12 gap 345
then the needed short was between 4 and 5 (HP_NB_SENSE signal).
I remove the old short and resolder all the pins from Headphone and Mic connectors. Now everything looks OK. Hope this was the problem : a cold soldering issue.