How do i connect this socket?

[confounded]

Hi, im not sure how to connect a 2.5mm power supply socket to the pcb i have.
I'ts a project from a magazine. The schematic shows 3 terminals on the socket, as i've shown on the top half of my sketch.
The pcb has 2 of the terminals connected together, as i've shown on the bottom half of my sketch.

I've attached pics of the socket.

I have used my multimeter to measure resistance between points, the results are:

with no power lead connected:
A-B = open circuit
A-C = open circuit
B-C = short circuit

with power lead connected
A-B = open circuit
A-C = short circuit
B-C = open circuit

Which points on the bottom half of my sketch are A, B and C?

 

[Hayato]

You have a "selfish" type female conector.

Is your 2.5mm plug connected to anything? Your measurements are a bit strange, because with or without the plug, the "A" terminal should never make contact with any pins. (Only if your 2.5mm plug is already connected to the seconday of a transformer).

"A" terminal will never change, so one wire will go there.

You are going to play with "B" and "C".
If your plug is already connected to a transformer, then the other pin you are going to use is "C".

"B" terminal will only work when there is no plug.

 

[confounded]

thanks for replying hayato.

Yes, my plug is connected to a transformer.
Thanks i now understand how the socket is connected