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Old 03-09-2013, 08:58 AM   #1
rancidryan
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horrible horrible earth buzz

recently acquired a fireman, and its got this horrible earth buzz until i touch metal! ive checked all the connections and re soldered the dull looking ones, but does anyone else have any ideas? its driving me crazy
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Old 03-09-2013, 09:21 AM   #2
GABarrie
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get a multi meter set to continuity testing, touch the bridge with one probe and the output jack with the other, if there isn't continuity you need to attach a ground wire to your bridge
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Old 03-09-2013, 09:46 AM   #3
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There is a wire from the bridge maybe its poorly connected at the stud end? That wouldmbe a nightmare -.-
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Old 03-13-2013, 01:41 PM   #4
sethasaurus
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Check the connection between bridge and output jack, as GABarrie says.
If there's a break, you will need to check each end of the bridge ground wire. At the controls end, this is easy to examine.

If you need to check the bridge connection, the bushing ('stud') can be removed easily once the strings are out of the way:
Remove the bridge adjustment screw first. Drop a small screw (pointed end upwards) or ball bearing down the hole and start screwing the adjustment screw back in. The pressure on the screw/ball will pull the bushing out of the guitar body.
These are usually just press-fit into place, so should come out easily.

Another reason for a lot of hum is poor shielding on the control cavity. This is pretty common, even on some expensive guitars. There are a couple of fixes - line the cavity with some conductive paint or adhesive-backed copper foil (some people use aluminium foil with a bit of glue).
I recently bought a 'fixer-upper' that had the same problem you describe - tons of noise and hum and it decreased when I used my hand to ground anything. Lining the control cavity completely fixed the problem and now it is dead silent.
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Old 03-13-2013, 01:43 PM   #5
ohaple
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Ive had some issues before if you have it shielded. If the shielding is somehow touching bare wire, you might have problems, and when you touch a screw on the pickguard or something, it goes crazy.
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Old 03-13-2013, 06:30 PM   #6
sethasaurus
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Everything needs to be grounded - i.e. cavity shielding, pot housings, bridge, output socket - preferably a star ground (all to the one point), otherwise you may get ground loops which cause hum.
(This is not critical, for example, my cavity shield connects the pot housings which are grounded to bridge, output socket and pickup shield).

I haven't actually seen the ground loop problem with a guitar, as the actual resistances in such a small space are very low.

If the cavity is shielded but there is no connection to the output socket, then you're not going to have a ground that will sink the noise for you. In this case, (for example, as you said) you touch the pickguard screw and transfer noise into the guitar. If it was grounded, you wouldn't get that.

If you are touching the bridge and it goes quiet, then the bridge wire is probably fine but also not grounded, as you are grounding it (and whatever happens to be on the same circuit) via your body.

Hope that is not too confusing.

You can easily test continuity between all these points.
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Old 04-04-2013, 04:41 PM   #7
rancidryan
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yeah ive checked between all the grounds with a multimeter. they all seem to be okay. I've noticed that if i turn my tone all the way down the buzz seems to go? would this indicate a dodgy tone pot?

going to try star ground if not i think
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Old 04-05-2013, 05:57 AM   #8
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Post us a photo of the internals.

All your grounds could well be connected, but if the wiring is miles of single core tangled spaghetti for everything (which Ive seen many times in the past on here) you will have a bit of work to do to get it quiet
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Old 04-05-2013, 12:36 PM   #9
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Old 04-05-2013, 07:57 PM   #10
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Yep.

You've got quite a bit of work to do.
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Old 04-06-2013, 06:12 AM   #11
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what do i have to do then? if i turn my tone knob down the buzz goes ive noticed and also that pot makes noise (not through the amp) but just when i turn it
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Old 04-06-2013, 07:48 PM   #12
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You can try replacing the pot. It seems it's being used as the star ground point. All the solder heat may have warped the wiper.

And if youre going to replace it, then I'd replace all the spaghetti with shielded wiring. The miles of single core red wires, the yellow wire that couples your vol pot and tone pot are all hot wires. All that single core wire acts like an antenna and picks up electrical noise.

I cant tell what the rest of them are. Two cables do appear shielded, Im guessing these are from pickups. Can't tell what wire goes to the output jack, but it should be shielded cable also

Any wire that carries a hot signal, should be shielded cable.
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