After some time I re-started an old model B.
Preparing the card with latest Jessie was easy, so I could fire up the old iron.
Now I am having a major issue about networking
- Ethernet (and wireless) connection is lost after a short time and there is no way to have it up again, unless I reboot the machine. I saw some services connected to networking being in the exited status
Same OS is working great on a Model Pi 2 created with same image (no issues at all, also wireless card is working great)