DC Jacks: finding out which lug is which

[choklitlove]

how do you do this?  it sounds kind of noob of me, but is there a positive way to do so?

this is the one particularly in question:

http://www.allelectronics.com/cgi-bin/item/DCJ-25/190/2.5MM_DC_JACK,_PANEL_MOUNT_.html

i thought i knew, but i'm having problems.  thanks!

[chokeyou]

first and foremost, I'd steer clear of that one unless you're using a nonconductive enclosure.

but the best thing to do when in doubt is break out the multimeter and check for continuity between the parts and the pins.

[choklitlove]

first and foremost, I'd steer clear of that one unless you're using a nonconductive enclosure.

yeah, i've heard about that.  but i can't even get it to work without it being mounted.


okay, i found this:


i tried it, and it's still not working.  is it possible that my pedal is supposed to be positive tip or negative tip (or whatever that's called)?  it's the old little big muff, so i guess it could be.  if so, how do i make this work?

[choklitlove]

update:
i don't think anything is reversed.  it works with a battery.


maybe there is something wrong with my jack?


i don't know.  it's getting frustrating, though.

[Mark Hammer]

I have a bunch of these, and yes they are awkward for installing unless you have a nonconductive material separating the jack and the chassis.

If you look inside the jack, you will see a little bump sticking out on the inside wall.  This is a little spring leaf that brings two of the solder lugs into contact.  When the barrel plug is inserted, the shaft of the plug pushes that little bump out of the way, and that default connection is broken.  This is how the power source is switched over from battery to wallwart when you stick the plug in.  Unfortunately, it also means that the outside of the plug MUST be used for V+.  For the rectangular plastic jacks that Boss uses (which simply slide into a slot provided), that'as not a problem because the jack is not grounded to the chassis.  In this case, however, the outside of the jack (hence the outside shaft of the plug) will also be in touch with the chassis UNLESS THERE IS SOME INSULATING GAP OR MATERIAL BETWEEN THE JACK AND CHASSIS/GROUND.  If the box is plastic, no problem.  This jack will do exactly what you need it to do.  If the box is metal, big problem.

One possible solution is to drill an oversized hole, and use large plastic/fibre washers on each side of the hole.  Tightening the nut on the jack will then pinch the two washers (inside and outside) together to secure the jack.  There doesn't seem to be tons of thread on the jack, though, so that solution may only work if the washers and chassis walls are thing enough.

[choklitlove]

that all makes sense, but it should work when it's not even mounted, right?  i just can't get it to work.  and for some reason, i can't get the standard boss style to work either.  like i said, though, a battery works.  i'm guessing that it's something to do with my adapter, although that's strange.  i'm using the 1Spot that worked with the old dc jack that used to be in this same pedal.  what's going on?!

[ianlogan123]

i'm glad I read this thread. I bought the same type of jack and was going to use it, but will now consider something else.

Ian.

[jxoco]

okay, i found this:


i tried it, and it's still not working.  is it possible that my pedal is supposed to be positive tip or negative tip (or whatever that's called)?  it's the old little big muff, so i guess it could be.  if so, how do i make this work?
[/quote]

try reversing the two black wires, you may have it wired so that when the power supply is plugged in, the power supply connects to the battery and the effect is taken out of circuit.
Rather than the correct way, when the power supply is plugged in, the power supply connects to the effect and the battery is taken out of circuit.