9V Socket Wiring 2 pin vs 3pin

paulphoenix

Can anyone help/confirm please? 

how do i wire up a 2 pin 9V socket? 

my supply is centre negative (standard boss type supply)

any help greatly appreciated.  

Sporky

Ground to centre, 9v to shell.

Unless I've misunderstood the question?

paulphoenix

maybe i should have asked: 

is the long lug + and the short lug - ? 

Sporky

D'you have a photo?

Or, better, a multimeter so you can check?

paulphoenix

no wait maybe i should have asked: 

if my supply is centre negative which lug do i connect the ground wire to? 

paulphoenix

i'm obviously too old as i struggle with uploading photos on this forum or maybe i struggle with photo hosting sites! 

i have a multi meter yes.

randella

Set the meter to DC resistance.  Put one probe on the centre pin of the socket (careful it ONLY touches the pin!), and touch the other probe on each of the lugs in turn.  One of the lugs will read 0 ohms on the meter and the other won't.  Connect your ground wire to the lug which read zero ohms. 

Just for reference - when this sort of DC supply unit is said to be 'centre negative', it's not strictly true (usually) as the positive is at +V (in your case, 9v) and the 'negative' is ground or 0V.  It's a bit misleading as in some circuits you'll need a supply with V+ and V- as well as ground (0V).

Sporky

Or if the multimeter has a continuity buzzer you can use that - might be easier than trying to hold the probes on and watch the screen at the same time.

Or it could be just me that's so ham-fisted.

randella

Sporky said:

Or it could be just me that's so ham-fisted.

Nah, I'm just too cheap to upgrade my meter to a posher one with a continuity buzzer and as a consequence forget that such luxuries exist

Sporky

I have a nice Fluke and a cheapo one from Rapid - it's the cheapo that has more features.

Not as accurate, but for guitar stuff accuracy to Fluke standards isn't awfully important.

Roland

The third pin is there to allow a battery to be shut out of the circuit when a power lead is pushed into the socket.