Quote: Take your DMM, set it to measure conductivity or resistance. Touch the center pin with one probe then the probe contact pins of the power jack. When your DMM beeps (conductivity) or reads zero ohms (resistance) then you've found the corresponding contact pin. The center pin is positive, the sleeve is negative. What kind of sockets did you buy? Sockets come in two flavours: PCB mount and chassis mount. You need chassis mount sockets since you don't use a PCB. Chassis mount sockets usually have solder eyelets.