What is the proper size for the beagle bone DC power connector? The SRM says, “2.1MM center positive x 5.5mm outer barrel” but a number of connectors I have that state 2.1x5.5mm will not mate as they are to large outside diameter and they measure 5.5mm OD as stated. A 5mm OD connector seems to fit just fine. What is the proper size? Is the SRM in error or did maybe some of these boards get built with slightly off sized DC power jacks?