Grounding / Shielding advice

peejay123

I have a Japanese Jaguar which still has all its original electronic parts. Recently I've been getting some fairly loud hum, I'm pretty sure this is a grounding issue, but I haven't managed to find something about this particular issue online. Most posts I've read talk about touching the strings to see if the hum gets louder/quiter. This makes no difference to my Jag, though if I touch the bridge or metal plates that hold the pots/switches/jack it goes away.

I've opened it all up and everything looks connected. I guess it could be a dry solder joint? But would like a second opinion before I get the iron in there!

Also, As xmas is coming and I'll have some spare time, I'm thinking I'll apply some shielding paint while I'm sorting this out. I'm in the UK, no shop sells it here online and the Stewmac stuff is very expensive. Can I use any conductive paint or does it need to be a particular type of paint for guitars?

I'm not going to replace any of the components (ie. pickups, pots, etc) unless they are broken, is there any other maintenance worth doing to the electronics while I've got it all open?

Cheers

Joey

peejay123 said: Most posts I've read talk about touching the strings to see if the hum gets louder/quiter. This makes no difference to my Jag, though if I touch the bridge or metal plates that hold the pots/switches/jack it goes away.

The noise goes away if you touch the bridge, but not the strings?

peejay123

That's right. But actually I've just realised something... I have GraphTech String Savers barrels on the bridge that are not metal so that's probably why touching the strings make no difference. The tremolo on my particular model isn't grounded either (there's no drilled hole in the cavity).

Joey

They usually ground the bridge thimble that's embedded in the guitar... the treble side. Your gonna have to go to the hardware store, buy a 10" or 12" long drill bit... that's about 1/16" or 1/8" in diameter (just large enough to pass a single stranded wire through). You need the longest bit you can get cause your gonna have to put the bit in a handheld drill and pretty much lay it flat on the guitar to get the angle you need to get from the tremolo cavity to the control plate cavity. Lay down a couple layers of masking tape where the drill bit is gonna meet the tremolo cavity, so it don't f*ck up the paint. And check... double check... triple check that when you get the length you need to get into the control cavity that your drill chuck doesn't touch the guitar finish either.

Once you pass your ground wire through, you'll have to scuff the bottom of the tremolo somewhere with a file or steel wool. Then solder it your ground wire to the tremolo. And easier solution {if you can't get that solder to stick to the tremolo) is shield the tremolo cavitiy with copper/aluminum tape. Let each joint overlap by a 1/8" and come out the tremolo cavity onto the finished paint of the guitar. Crimp a tongue ring onto the ground wire, drive a screw thru it into the shield. When you screw the tremolo down, it makes contact with the shield laying onto of the guitar and completes the circuit.

And the other end of the ground wire can ususally go to the back of a pot in your control cavity... just look how everything else is grounded.

peejay123

That's an awesome bit of advice, really appreciate it. Thanks.