Post
by morganp » Sun Apr 13, 2014 6:22 pm
Hard to tell exactly from the photos, but it looks to me like the leads at the output jack are reversed? Usually black is ground and goes to the sleeve connection, and the hot goes to the tip. Maybe I'm seeing the jack wrong, or maybe you've chosen different colors, but your description of "noisy ground" could potentially jibe with these being reversed. Can you tell me where the other end of that black one is connected to?
Ideally, you want only one path to ground for each component. Multiple paths to ground can create extra noise from ground loops, and other problems. Maintaining just one path is hard to do when shielding, especially with a complex setup like a jag. But I try to make sure there is a clear path for each bit all the way to the ground at the jack. It's possible for this path to be along a bit of shielding, or along a metal control plate, but these can sometimes be inferior to an actual ground wire, because you can't always be sure the shielding or control plate is making as good a connection as you want.
Like, ok, so, look at the back of the tone pot for the lower circuit. You've got the cap soldered there, as a path to ground. How does it get to ground from there? Often we'll put a wire from the back of the tone pot (a common and convenient spot to run all the ground wires to, including pickup grounds, and a better connection than just shielding) to the jack's sleeve terminal. Technically, you've got a path to ground from the cap's leg to the tone pot housing, and then through the physical connection of the pot being screwed to the control plate, and then from the control plate to the jack's housing; in practice this can be a little iffy depending on the washers, what kind of jack you're using, etc, but usually works for a metal control plate. But sometimes it's more clear-cut to just run an actual ground wire at those spots, ie, tone pot housing to jack sleeve.
Another problem that can occur is the shielding making contact in a spot where you don't want it; if you've got a hot lead that accidentally comes in contact with the shielding, it can short around that component or, more likely, send all of your signal to ground. So make sure none of those hot leads touch the shielding anywhere.
Also, it looks like the solder joints on the pot backs are a little iffy; a hotter iron (applied for not too long) can work a little better, but we don't all have a good one (I for one definitely need a better iron). If you've got a multimeter, you can check for continuity to make sure all the connections are good; any that are splotchy or hazy might be a cold joint.
Hm, I can't tell if there's a path from the upper circuit's ground (looks like you're using the back of the tone pot here as the ground hub) to the jack. Multimeters are great for this too; just check that there's a low resistance (but not noresistance) between that upper circuit and the jack's sleeve connection.
Anyway, yeah, jags are pretty busy in there. To recap: in general, make sure solder joints are solid, make sure you have a clear path to ground, make sure the hot signal isn't touching the shielding anywhere. And for this guitar, check that your jack connections aren't reversed. Report back, and...
Good luck!
Edit: oh yeah, as far as the shielding overlapping the control plates: as long as it's not in danger of contacting a hot lead or terminal, I'd say leave it; often that's how folks make that ground connection for shields, is just letting them contact the plate and get grounded through that, so, shield touches plate touches pot housing touches ground wire to jack. And then your shields are grounded! Again, use a multimeter to check continuity.
