# 9V jack - long part positive (+)? Center negative (-)?



## Cucurbitam0schata (Jan 21, 2020)

Hey Folks - 

Total noob question: I got these 9V jacks from Tayda (part #A-991). I'm having trouble figuring out which lead off the jack is (+) and (-). Is this like caps and LEDs, where the longer lead is (+) and the shorter lead is (-)? The last 9V jacks I got had a diagram... these don't!

Also, I'm sure there's a tried-and-true method for troubleshooting this. As in, is the center _always _negative? Sides/sleeve _always _positive? If anyone has a pro tip, I'm all ears. 

Thanks!


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## phi1 (Jan 21, 2020)

My tip:

Get comfortable using a multimeter to double check what goes where, even when you do have a layout. It helps to learn what’s going on. My opinion is learning to figure it out yourself is generally better in the long run than getting a quick answer. 

Standard power for guitar pedals is “center negative”, so the sleeve is positive. So, using the continuity beep setting on your multimeter, see which lug connects to the the center pin of the jack, and that lug will be your negative. 

Or plug power into the jack and use the Vdc setting on the meter to determine which lug connection is correct. 

I’ve only used that style jack a couple times, so I don’t remember which is which (I’m sure someone else here does). I’ve just checked w the multimeter right before soldering.


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## Nostradoomus (Jan 21, 2020)

You got it, long lead positive.


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## Robert (Jan 21, 2020)

Cucurbitam0schata said:


> As in, is the center _always _negative? Sides/sleeve _always _positive?



That's correct, for a typical pedal power supply the center pin is always negative.     Most DC adapters for _other _consumer electronics are opposite, so you have to be careful with those.

Your drawing is correct, the longer lug is the sleeve (positive).


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## Cucurbitam0schata (Jan 21, 2020)

Love it, ya'll are giving me fish _and _teaching me how to fish. Best of both worlds. Thanks, pals!


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