static noise issue

[brokin009]

hey guys. i need a little help. i have an issue that had just arrised and i dont know how. im getting a static nowthrough the amp when im not playing, when its just plugged on and turned on. anyone had this issue before? anyone know where i can start to look?

[Chuck]

Wiser folk than me will chime in, but it sounds like a grounding issue. Does the noise go away when you touch the bridge? Did you shield the cavity? Did you make sure there's a ground from the bridge to the back of one of the pots?

[brokin009]

thanks Chuck yeah all things have been earthed the only thing im not sure of is if the earth wire to the tunomatic bridge is still connected. i honeatly dont known how it would of disconnected but ill still check it. it does go quieter when i touch the bridge or leabe my hands on the strings but it still is a fair bit louder than before.

[Simon Barden]

Valve amp or solid state? If it's a valve amp, it could be a noisy tube. You aren't going to get true static noises if you aren't even touching the guitar. Turn the guitar volume right down (which will connect the signal wire to ground). Are you still getting the noises? Yes, then it's the amp. No, then it's something to do with the guitar. One step at a time.

[brokin009]

ok checked it out amd the noise drops of once the volume is turned right down

[Simon Barden]

OK, so it is almost certainly guitar related. If you've got a multimeter, first do a continuity test on all the ground connections back to the jack socket. All readings should be close to zero, certainly less than an ohm.

Also check for noisy pots. Move all the pots fully back and forth several times, which should clear out any dust in them, but if they are still noisy when you turn them, then a spray with a contact cleaner like Servisol 10 should help.

Do the same with the pickup selector switch.

Which guitar is this on?

[brokin009]

hi Simon, thanks for your help. its the flying v. i was told to upgrade the pots to 500k as the guitar came with 250k pots. i kept the volume as 250k would that be an issue? maybe thats the issue.
i have put the standard pots back in but it still has the same noise like a buzzing through amp. softer when clean but when i use the amps distortion it is alot worse. like im using really cheaps leads. but i know this one is good. its a dimarzio lead and i plugged it into the prs and not issues there. had to rule that out.
is there a way to check the pots themselves?

[Simon Barden]

No, 250k would only make them sound a bit duller, nothing else. I now see you have one volume and two tone pots (my V has two volume and one tone).

It's not that easy to check the pots themselves without unsoldering at least one wire. But if you can sweep each volume pot from end to end without getting any sudden breaks in the sound, then the tracks are OK. Likewise with the tone pot - though that should get duller as you turn it down. If the sound suddenly becomes clear again, or the sound remains clear until a certain point and then gets duller, then the tone pot track is broken and it needs replacing (I found that on a mate's strat-style guitar - it was very bright indeed because the tone circuit was basically disconnected until you turned the tone pot around halfway as the track was broken).

Looking at your build diary, I see that you put shielding tape in the cavities and on the control plate, but that you've trimmed it off flush with the surface of the guitar. Have you soldered any ground wires to this? The copper tape all needs to be connected to ground to work effectively. The tape on the back of the pickguard is grounded through the pots. For the control cavity, running some of the tape over the edge and onto the top of the body allows the tape of the pickguard to make contact, and so ground it without running any special wires. But the pickup and jack cavities need the screening to be specifically grounded. Without it, its just at a floating potential and may be making any noise issues worse. Did you run any ground wires to these at all? You can try and solder a wire to the copper tape, or you can get a small screw and a washer, wrap the bare end of a wire round the screw and screw it in so that it holds the wire against the copper (in the pickup cavities place it so that it doesn't foul the pickup). If you run the wires back to the main control cavity and attach the wires to the tape in that by the same method, then all you need to do is run extra taps over the edge so that it makes contact with the top when screwed down and you should be OK (obviously keep the tape inside the pickguard boundaries.

This may not cure your noise issue, but it will certainly make your screening far more effective.

You mentioned a PRS. Presumably you aren't getting a similar noise from that? Just wondering of there's a new external source of noise that is causing you problems, but it should be noticeable on all your guitars.

[brokin009]

wow thabks heaps Simon. i didnt know that the tape had to be earthed out to work. the pots or the switch was not in contact with the insulation tape. i have now put some extra insulation tape so the pots and switch now get in contact with the tape.
question, if the pots now are in contact with the tape and i have put some more tape on the body so both scratch plate and body tape are now going to be touching when screwed down will that be enough or do i need to wire and screw it into the tape?

[Simon Barden]

That will be fine for the main control cavity, which is where the main source of any external noise pickup will be. As you've got humbuckers, screening the pickup cavities has less of an affect that it would do with single coils, but it's still worth connecting those to ground. As I said, this can be back to the main control cavity screening.

The thing to watch out for now (as the tape is now connected to ground) is any loose bit of signal wire touching the copper and grounding the guitar signal. This may have already happened before you grounded the copper tape, and the copper was acting as an aerial and feeding noise into the signal path, rather than taking it down to ground. Your tone capacitors have a live leg that is currently running parallel to and close to the shielding. If a wire moved and caused the leg to touch the shield, then you are going to have problems. So I'd stick a bit of insulating tape over the copper in those areas where there's a possible risk of wires touching (don't worry if it's a part already connected to ground). Check that there's no stray whisker of wire poking out from any of the pot and switch connections - it's very easy to do and difficult to spot.