How to Check for Ground Continuity Mode Multimeter

This week I'm gonna talk about my trustiest of trusty tools, the multimeter, and the feature that I use the most: continuity! If you have a meter, it's the option that looks like this:

When you are testing continuity, any time you touch the two leads to two metal parts that are connected, your meter will beep. This is great when you need to know why your guitar is making awful electronic noises. In fact, this should be the first thing you check on any electric guitar as it's easily one of the most common failures, besides jacks which we've already covered here. So how do you know what's supposed to be grounded? Easy! Everything metal! Well, everything that isn't your signal path (which I'll talk about in a future post), or I guess the pickup magnets aren't grounded, but otherwise…all the metal!!! You can do a super quick check of your string grounds and all your components like this:

It's best to check all grounds with one lead connected to the output jack because it (the jack) is the most important ground, and it'll make the most noise if it's not connected. If your meter doesn't beep at all when you have one lead connected to the jack, then you can safely bet that you found the problem. You can see if everything else is connected by resting one lead on the strings and then using the other lead to test the rest of the components just like above! Logical!

So wait, why do we ground things?

Because there are ambient electromagnetic fields all around us all the time, especially in our modern cities. They come from telephone wires, transformers, electrical boxes, wifi, TVs, lights, even that box fan you keep in your practice space. That means that there are electrons floating around in the air, going in and out of all kinds of things, walls, guitars, bikes, cars, ancient VHS copies of Teenage Mutant Ninja Turtles, and even you! And when they come into contact with the metal parts of guitars, especially any parts that are involved in generating or manipulating signal (so… everything), you will hear them–the electrons, that is. If your strings aren't grounded, any electrical interference that comes into contact with them will get induced into your signal through your pickups, and then your amp will make that noise even louder! When they are grounded, that noise gets shunted to ground (Thee Ground, as in the Earth), leaving the pickups free to sense only the vibrational energy of the strings, sans electrons!

It's kind of the same reason why we shield signal, which we talked about here.

So the cool thing about strings is that they are metal, and electric guitar bridges are metal too, which means that as long as they are touching each other (stop it!), all you need to do to ground the strings, bridge, and tuning machines is connect a wire from any one of those parts to the ground of the output jack. Most often you'll see the wire for string grounds (as they are most commonly referred) going from under the bridge to the back of one of the pots. But if you look closely, and if your guitar is wired properly, you'll see that the pot housings are all connected to the output jack too! This can be less obvious with some guitars like Teles because they have metal control cavity covers that connect the pots, switch, and jack without the need for extra wire, but it's all grounded! And you can test it for yourself with your handy multimeter!

Enjoy your tinkering!

Happy Saturday, hope you have a great week. See you next time.

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Source: http://landisguitars.com/2017/04/15/how-to-use-a-multimeter-to-check-grounds/

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