By an "AC socket" do you mean a socket that looks like a AC wall socket you might plug your toaster into () or a socket that you could plug in an alternate source of power for the flash?
Originally Posted by olleorama
If it is the former, it isn't for power at all - it is a "household" style connector for flash synch (as noted above).
The latter type of socket isn't found very often now, but I recall having a small Braun flash that had a socket that you plugged one end of a proprietary cord into, with the other end plugged into the AC socket in the wall, for power.
The "household" style synch cords were both good and bad - good because they provided a strong and simple contact, but bad because they could be mistaken for something that plugs into a wall.