Ground Issue I Think

[a_novice]

Hi All, i'm sure this has been covered but not quite sure i can find what i need so posting another query. I have just put all the electronics into a new build, and when i tried it out to ensure its working i found i have a huge noise issue and assume its grounding.

I have 2 hum buckers that are plug and play and doubled checked everything. Ok, so here is what's happening:

When i plug the guitar in and don't touch anything its really noisy, a loud buzz/humm. This doesn't happen on my other guitars. When i touch the strings or any metal part on the guitar (wraparound bridge, washer around the switch) the noise completely goes away.

I did run a ground wire from inside the stud wall to the cavity but for some reason it doesn't seem to be working (my assumption) so i ran another from between the inside of the stud well and the stud and that didn't help either.

In a separate query it seems that the graduation of the pots isn't as i expected, they are either on or off almost. But this could be affected by the grounding issue so trying to fix one thing at a time.

Now given i can't take out the stud wells, i don't know how to retro fit a ground wire. Its not an easy body to drill a hole in for this. Maybe i can't now??

I also intend to add coper tape int he cavity but not sure this will do a lot.

Thoughts?

[Sonic Mountain]

That the hum goes away when you touch the bridge usually indicates that earth is OK. To reduce the hum, your best bet is shielding. This is tricky in a semi hollow as you really want to contain all the electronics in a Faraday cage. That said, any extra shielding is helpful. So putting some copper tape in the cavities is not a bad idea. Ideally the shielding should be grounded as well.

To your other point regarding the pots, it's possible you have them wired back to front. Just double check that you have used the correct outside tangs. The center tang is the sweeper and looking at the bottom of the pot with the tangs facing up the left hand one is the output. You can actually swap those two around, but not the outer two (as you may have- ALSO I'm still learning here so if someone know better please correct me)

Finally, as long as you will be looking at the pots, just make sure all the connections are good and you don't have any stray bits of wire touching stuff they shouldn't.

[a_novice]

Yeah, as soon as i touch the strings or anything metal (even the input jack plate on the outside or the metal end of the guitar leed) the buzz/humm goes away completely.

I'll try adding the shielding and see if that helps but will also double check the wiring (was my first attempt and even though its plug and play there is a chance i have something wrong). I did switch the pickups around on the switch because up was neck instead of bridge so figured they could just switch over ok.

[Simon Barden]

A huge amount of hum normally indicates that you've either got the output jack wired the wrong way or that you've missed a ground wire connection on one of the pots. As your volume control seems to be on/off, I'd suspect the latter, but it's worth checking both.

[a_novice]

Thanks Simon, i'll check this as well. There was a huge amount and then i switched the output jack wires which helped a lot (reduced by half) but still much louder than it should be.

I noticed that turning the tone to max removes the noise completely so i thought maybe a ground issue as the tone essentially just cuts the noise (filters).

[a_novice]

OK, managed to get rid of the hum/buzz completely! I shielded the electronics cavity, but the main issue was the input being wired incorrectly as Simon mentioned. Now the pots work as expected and really happy with the sound of the EMG H4(A)s...love the sound. Still have some slight issues with action that is really hard to rectify on the treble side but willing to put up with given the twist in the neck that i can't fix. Overall really happy with the build.

The plug and play wiring was also really cool, nice not to have to solder for a change. Need to think about next build :-)