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Fixing Ground Hum


FadeAway
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You could have had a ground loop going on. Grounds can be tricky, as just slapping wires together may not get the result you are looking for. What kind of grounding scheme do you have going on? Have you made sure that all other grounds are properly connected? If you reverse ground and signal of a pickup, it can sometimes cause hum issues depending on the grounding scheme.

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I would assume the hum also goes away if you touch the strings or the bridge. It should happen when you touch anything connected to the ground circuit. It's a very common issue. You need to check your wiring and make sure all the necessary grounds are connected.

For a strat style guitar, that means all pickups must be grounded, as well as the bridge, and the ground must be connected to the ground on the output jack.

Edited by dpm99
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Narrow down the problem. Without unplugging anything else, pull the cord out of the guitar and put it directly in another guitar. If that guitar does not hum, the problem is obviously in the guitar you wired. If this is the case, and the guitar is wired correctly, I can only conclude that the guitar is haunted. You can test for this by throwing it in a river. If it floats, it's haunted. Burn it and scatter the ashes. If it sinks, it's not haunted. You won't get much use out of the guitar after that, but at least your mind will be at ease.

(Personally, I'd start checking connections if I were you. We've all been there. Just don't give up.)

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It's probably some tiny little piece of wire that's touching something it shouldn't, or not touching something it should. Just make sure it's all clean. Are your hot wires shielded? And if so, is the shielding in those wires connected to the ground? (They should be.)

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The hot/lead/positive wires are the ones you want to shield. The ground wires can be unshielded. Some will disagree with that statement, but I hold to it. Most everyone will tell you to ground the lead wires. And like I said before, if you don't ground the actual shielding that surrounds the lead wires, you haven't shielded anything. It's a frustrating process sometimes, huh?

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The hot/lead/positive wires are the ones you want to shield. The ground wires can be unshielded. Some will disagree with that statement, but I hold to it. Most everyone will tell you to ground the lead wires. And like I said before, if you don't ground the actual shielding that surrounds the lead wires, you haven't shielded anything. It's a frustrating process sometimes, huh?

Yup, but not TOO hard to figure out. My jag had me stumped for awhile, but I finally found that one loose wire that was suppose to shield one of the control cavities. Too many wire all in one place.

Also, try plugging in the guitar and touching the shielding. If it doesn't go quite, it's probably not shielding.

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The first guitar I ever wired was a simple strat clone. The second one had two P-Rails. It had neck/both/humbucker switching on a tele-style blade switch, one volume and one tone, push-pulls that switched between single coil/P-90/series humbucker/parallel humbucker mode, a six position varitone that alternated capacitors and effects, a variable treble bleed on a hidden micro-potentiometer, and a kill switch.

When I plugged it in and it didn't work, you can only imagine my frustration. I'd wired it according to what I thought was a good diagram, and it was, except that one of my switches didn't work the way the diagram said it should. I pulled the whole thing apart and started over. I used test leads.

test-leads.jpg

First I played around connecting pickup wires directly to the jack and holding a tuning fork over the pickup until I understood how that all worked. Then I sat down and took a hard look at the switch to see how the connections worked. I tested my theories, and realized that you should never, ever buy one of those ridonkulous tele switches that StewMac passes off as a decent guitar part. (I like StewMac...just not that particular item.) Then I started experimenting with the push-pull pots until I understood how they worked. I tried random lug connections, just to see what would happen. I did the same with all my components, and each one was easier than the last.

By the time I was done, I didn't need a diagram anymore. I'm no expert on this, and there are a lot of guys here who know much more than I do about guitar electronics. My point is that for those of us that don't have a background in electronics, there's a learning curve. I used to hate wiring, but that was just because it was all voodoo to me. There was a point when I really did want to just throw my guitar in the river to see if it would sink. Stick with it and you'll get past that point. Ask questions. And if you do happen to have on of those pitiful tele switches from StewMac, film yourself smashing it with a hammer and send it to their customer service department.

This is the one, curse the day it was made!

http://www.stewmac.com/shop/Electronics,_pickups/Components:_Switches_and_knobs/Lever-action_Pickup_Switch.html

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thank you for your continued information. This hum is pissing me off XD, I have repeatedly looked at the factory diagram, and resoldered many connections, yet it still hums as much as ever, I think that the main hot wire too the output should be shielded now that I have played around a bit, because when I touch the insulation, it hums louder. Also, will I inevitably be the ground for the guitar?

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OK! its fixed. After looking at it until I went cross-eyed, I said @*$* it, swapped out the out jack because it was the only part I wasn't sure of, and BOOM no hum. BUT WAIT, I put the pickguard back on and it starts humming again. Then after a few more minutes of blindly staring at the thing I notice the switch is touching the shielding paint, grounding it. Once again, duck tape saves the day. I just put a strip in between the switch and the body and the thing is quiet.

thanks for all the comments helping :D

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