Help me wire an older skool DC jack? Got me stumped

[chumbox]

Hi All

Have been repairing an older model DOD 440 envelope filter for a friend and I have it working off power but I cannot seem to work out how to wire the DC jack for battery and power.  It is the older style that takes a tip/sleeve plug (like a tiny guitar jack).  Here is the jack from the outside http://medias.audiofanzine.com/images/normal/dod-440-envelope-filter-629372.jpg

On the inside it has three lugs like a normal DC jack and I checked with my multimeter where all the power went with the plug in and then wired the battery +ve to the spare lug but it doesn't work.  So I have the GND and +9v power lugs right, just can't seem to wire a battery as well, even though it originally had one but had fallen off. Hopefully this all makes some sense.

 

[mcknib]

I had the same problem with a centre positive Turbo Rat and ended up swapping the + wires around to get it working as far as I can recall, the LED only lit with battery and not adaptor or visa versa. I was thrown with it being centre positive and living in Europe it's almost always centre negative. As you probably know most US one's with the miniature jack plug are centre positive.

This may help

[chumbox]

Thanks so much mcknib.  I'll give this another whirl thanks to your diagram.

Much appreciated!

[italianguy63]

Note:  I hear all kinds of horror stories about people plugging the wrong wall wort into the wrong pedal and blowing them up with reverse polarity.

It is a great practice to color code / mark / highlight any pedals and worts you have that are "reverse polarity"  

MC

EDIT-- and A/C vs. D/C for that matter too.........

[Brisance]

Tip: always when unsure about jack lugs, get your DMM and use the continuity/resistance setting to verify

[mcknib]

If it's one of the older open style DC sockets stick the jack in and it should be pretty easy to see which lugs connect to the jack tip and sleeve and as Brisance advised you can continuity check it just to make double sure.

A tip for future reference I just solder a battery snap to these and put them in with any pedals I sell so that the purchaser can play with it straight away with a battery rather than have to buy an adaptor, they're cheap and easy to make and because I'm lazy I use them a lot when testing builds rather than unplug adaptors from pedal boards etc.  




and +1 on what Mark done said too

[chumbox]

All great advice guys.  I've been using the DMM to test everything, just for some reason I must have something mixed up.  Should be able to re-solder over the weekend.