There seems to be a grounding issue with my guitar. The buzz doesn’t disappear when I tough the strings, but it does disappear when I touch the switch or output jack. What can I do?
On the .strandberg* bridges, the ground connection is provided by a wire that goes from the control cavity and wraps around the front screw that fastens the bridge. There is a small spring that connects the head of the screw with the adjustable saddle of the bridge. The string rests on the saddle, and grounds the remaining strings through the 0-fret.
Several things can go wrong in this assembly:
1. Sometimes, there is a bad connection between the wire and the bridge screw.
2. Sometimes, the way that the guitar is intonated means that the spring doesn’t end up on the head of the screw, in which case some anodization must be ground off (see link below).
3. Sometimes, there is oxidization on the spring, and it doesn’t provide a good connection, in which case you can lightly sand each end of the spring to get clean surfaces.
4. Lastly, sometimes the spring gets stuck somewhere inside the bridge and actually doesn’t touch the saddle.
There’s a description of all this in an old blog article: http://guitarworks.thestrandbergs.com/2009/10/24/ground-zero/ This description refers to an older version of the bridge, where you would always ground off the anodization. In the current design, it (usually) works by providing ground through the bridge mounting screws.
If you have access to an ohm-meter, you can easily check the DC resistance from the string to any other metal part on the guitar, like the switch. It should be close to 0.
To correct this issue, start by removing the bridge and see if touching the head of the bridge mounting screw gets rid of the buzz. If it does, then the problem is with the string not connecting the screw with the saddle, and you can sand off the spring and stretch it carefully to make sure it has a connection.
On most guitars, the ground wire will be attached to the G-string bridge, but some (in particular older) guitars, it is attached to the high E-string.