Wiring a power jack

[Joecool85]

If you wire it like it shows, and you have a battery in the box and plug in an adapter, will it just not use the battery or what?

[Processaurus]

right, it disconnects the battery + from the board +, and the AC adapter + goes to the board + instead. 

Make sense?

PS the metal jacks are no good for tip negative 2.1mm DC plugs, it shorts the + to the enclosure, which is connected to ground.  You can get crazy and try and insulate it, but its much easier to use the ugly plastic ones.  I wonder why Boss made tip negative the standard?  Seems kind of backward.

[Joecool85]

oooooh!  Tip negative is standard for pedals?  I did my fuzz that way because it was positive ground.  That makes sense now! 

Meanwhile, I thought my black coffee metal pedal was pos ground because it has negative center lol.

[KaptenSpark]

I've tried wiring a dc plug but I just don't get it. To me it seems like no power will get to the fx board if nothing is plugged in to the power jack. And i'm using those metal 2,1 mm plugs. Could someone explain?

[Paul Perry (Frostwave)]

I've tried wiring a dc plug but I just don't get it. To me it seems like no power will get to the fx board if nothing is plugged in to the power jack. And i'm using those metal 2,1 mm plugs. Could someone explain?

Some plugs have a "normally closed" switch built in, so if you plug the external power in, then that is connected instead of the battery.
And THEN, the power (whether from battery or external plugpack) connection is completed (via the ground connection) when the guitar lead is plugged into a stereo jack, wired so the plug closes the circuit. I think.

[KaptenSpark]

But if there's no plug in the dc jack, no power can get from the battery to the fx board, because there's no contact! Right? I'm kinda going crazy here.