DC jack continuity

[Tombaxter97]

Hi, I've bought these dc jacks and can't remember where from, they have two pins either side one longer than the other.
Is there anyway of checking which lug is negative and positive using continuity on multimeter

[Tombaxter97]

as I had a nice sound before i put into enclosure (ea tremolo) at 4.5v on test point then when i put into enclosure it now reads at -2.5v?

[EBK]

Without the jack being wired to your circuit, plug your power supply into it and measure the voltage.  That should let you know which terminal is which, and whether your power supply is still working.

You didnt post a pic....  Do your jacks have a metal casing?

[Tombaxter97]

I'll take a picture now, what of exactly so I can give you as clear a picture as possible

[GibsonGM]

Front and back of it....the pins, and also the rear where you'd make connections (solder lugs). 

[Tombaxter97]

[duck_arse]

the pins don't have a polarity until you tell them. the "boss standard" puts negative/0V/ground on the centre pin, barrel positive. the barrel positive is what causes the build problems w/ metal bodied dc jax. if you can see on the back/inside/wire side of the jack which lug is under the rivet, that is the centre pin. otherwise, use your meter on ohms/continuity, and test for which lug connects to centre and which to barrel.

on another topic, arising from your photo, don't use the lug-rivet holes on pots as solder eyelets. they are NOT for electrical use, but for mechanical stability of the lug-to-track. if'n youse stretches the rivet a tiny little, the lug goes loose, and the pot goes cronk. and if yu over-blob with the solder and short to the pot case, it'll be the divil to find. solder to the pin, or cut a little perf or vero, solder that to the pot pins, then solder wires to the board. this terminates both the wires and the pot pins properly.

[blackieNYC]

Google images for DC jack. Here's a nice article, or skip to the bottom photo
http://www.diyaudiocircuits.com/tutorials/diy-center-negative-power-supply/