Buzzing sound from guitar?

mattacjones

Ok, many times I have experienced a noise from the amp tha goes away when you put your fingers on the strings, and I understand that. However, I have the opposite occurring (humbuckers), so the buzzing starts when you touch the strings! Any ideas what that is?!
Thank 'ee

ICBM

Either the ground wire to the bridge/tailpiece/trem claw has come off, or the jack is wired backwards.

mike_l

I had that, it was a bad solder joint on the earth. I'd resolder the wiring as a first port of call.

mattacjones

Hmm, well, I put the soldering iron on the various connections around the jack, and where the braided wire is soldered to pots and where ground is soldered to the tremolo etc, loosened up the solder and let it harden again. Didn't make any difference - was that a waste of time? Also noticed inside the control cavity it's shielded, and buzzing goes away if you touch the shielding! It's a decent prs and too much fiddly wiring in there for me to start from scratch.

ICBM

If the buzz goes away when you touch the shielding but increases when you touch the strings, the problem is that the strings aren't grounded. There must be a contact problem somewhere between the bridge and the ground in the control cavity.

For what it's worth, reheating all the solder joints without identifying where the problem is is *not* a good idea, you can easily make things worse. Melting the solder without really getting it hot enough or adding fresh fluxed solder can cause cold joints.

mattacjones

@ICBM - thanks for that insight. Bugger!! Still, looks like there's something I can have a go at - there's a traceable wire that goes from the trem fitting (bridge). What is it that actually provides 'ground' - is it the pots? The braided part seems to be soldered across the pots. Cheers - of course I could take it to a tech, but seems like such a faff when it's prob quite simple.

Rox

I'm no tech wizard but have you checked if you have bumblebee caps installed?

ICBM

mattacjones said:

@ICBM - thanks for that insight. Bugger!! Still, looks like there's something I can have a go at - there's a traceable wire that goes from the trem fitting (bridge). What is it that actually provides 'ground' - is it the pots? The braided part seems to be soldered across the pots. Cheers - of course I could take it to a tech, but seems like such a faff when it's prob quite simple.

You should be able to trace it from the buzzing sound.

If the buzz stops when you touch the shielding, it should also do so when you touch the back of the volume pot.

There is a black wire which runs from there to the trem claw. If touching the trem claw doesn't stop the buzzing, either there is a broken or cold joint at one end of that wire, or the wire is broken in the middle - unlikely but not totally impossible.

If touching the trem claw *does* stop it, then the springs are somehow not making an electrical contact to the bridge - which I would find difficult to believe, but isn't totally impossible I suppose…

Rox said:

I'm not tech wizard but have you checked if you have bumblebee caps installed?

Ha .

mattacjones

By way of an update ... spent several hours fiddling about and tried a few things, but after a noisy buzzing rehearsal took it to a tech. Got it out to demo the problem, plugged in and .... nothing ... not a peep! 

ICBM

Sounds like you have a bad source of interference in the rehearsal room.

Dimmer lighting, computer power supply, mobile phone charger, drummer, that sort of thing...

mattacjones

Maybe, but it was two different venues, at home as well, all my others sound fine. We will see what comes back!

mattacjones

So the conclusion is, a loose pickup selector switch and overly long braided cover from jack plug causing a short (?). Touching anyway. Now silent! £15 from dan the guitar engineer in berkhamsted. 

mattacjones

aaarrrrrggg - this is driving me nuts! So, retrieved guitar (prs with hb) from tech, played through his amp, all good. Go to rehearsal, buzzing when played through my TK, but not when played thru my mates mesa. Come home, same buszzing thru both my TK and swart. WTF?! completely stumped! also tried other mains sockets including the one the mesa was plugged into. Other guitars work fine, so must be something to do with the guitar?

ICBM

Unless both your amps have the same issue, given that the Mesa didn't.

Are both UK voltage models, or US imports with stepdown transformer?

mattacjones

Hi, no both pukka UK models

ICBM

How very strange!

Guitar buzzes through two amps when other guitars don't indicates it's the guitar. Guitar buzzes through one amp but not another when both are plugged into the same socket indicates it's the amp...

If it isn't a massive faff, take the other amp to the rehearsal room next time and confirm that buzzes too. (And the Mesa still doesn't.)

mattacjones

I know ... bonkers. I need to be methodical about it but there can't be that much to go wrong. Both my amps have been faultless, so it's deffo the prs. Maybe I've developed some kind of magnetic aura that I didn't know about. 

ICBM

There's probably some special thing that Paul has built in so it only works through one of his own amps, or a Mesa - since these are the only approved combinations for a PRS.

mattacjones

Ok, so guess what? I have 'fixed' it. After reading some guff on the web about multimeters, I realised that the strings were connected to the ground of the output jack and that a multi meter would put current through the strings that could be measured at the jack.Unfortunately, I don't have a multimeter, but I do have some audio leads, a 9v battery and my tongue. So after some athletic analysis, I deduced that most of the gubbins relied on being soldered to the volume pots. I also deduced that the jack cground wire connects to the tone pot (which is also a coli tap switch). However, I could not spot anything connecting the volume pot to the output jack earth (unless it relies on the sprayed on black conducive material that cooats the inside of the control cavity), so I invented something and soldered a bit of wire from the volume pot to the casing on the coill tap (which is clearly connected to the jack braided wire). Hey presto, no buzz.God knows what's supposed to do that job, but there's a fault in there somewhere. Doesn't explain the non buzzing on the other amps though!! I'm exhausted now, going to lie down - then find a different tech to fix it properly). 

ICBM

mattacjones said:

I also deduced that the jack cground wire connects to the tone pot (which is also a coli tap switch).

That's bad wiring practice and I wouldn't have expected that on a PRS. I'm almost certain all the ones I've seen have the jack cable connected to the volume pot where it should be. The outer braiding is also soldered to the tone pot which completes the ground connection there. If they left off the connection at the volume pot that would definitely explain it, although not why it was silent with the Mesa!

mattacjones

You are correct, just checked the wiring diag. Jack earth shoud go to volume pot. The coild tap is already earthed from another wire. Simples, and got rid of my crappy fix. I wonder why the guitar tech couldn't see that and I wonder why it worked on those other amps! Anyway, I'm going to forget about it now, thanks for the pointers. Cheers