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I need help fixin a hum please.

Bluesey

New member
Joined
Jul 18, 2001
Messages
232
I just bought a Les Paul Classic Premium Plus and it has a hum in it when I am not touching the bridge. I will be changing the pickups, pots, and caps. Can someone tell me how to ground the bridge properly? Or is the hum common to the stock pickups in a Classic?
 

Davepaf

Davius J. Pufficus
Joined
Jul 15, 2001
Messages
4,250
Sounds like a bad ground somewhere? Is it a brand new guitar? Do you have a meter? Check your solder joints, make sure nothings touching that shouldnt be. Check the continuity between your ground and your bridge. It shouldnt hum if its a new one.
 

Bluesey

New member
Joined
Jul 18, 2001
Messages
232
I checked the ground to the bridge this morning and it looks good. It got the same continuity readings as the rest of the grounds like .6 to .8 ohms. What do you think????
 

Davepaf

Davius J. Pufficus
Joined
Jul 15, 2001
Messages
4,250
That meter should be pinned with almost no resistance at all on the ground wires. Youve got a short somewhere. check your output jack for a loose conection. Do all the solder joints look good?
 

Bluesey

New member
Joined
Jul 18, 2001
Messages
232
I checked the output jack and it looks OK. I'm using a Fluke meter and the leads alone read the same resistance. The solder joints look OK, no shiny ones.
 

Davepaf

Davius J. Pufficus
Joined
Jul 15, 2001
Messages
4,250
Well, you got me.:dohId have to see it. If your gonna swap all the guts out of it anyway, make sure you have a good ground to your bridge. Are you sure no ones fucked with the wiring or the pickups? You also might have a bad pot?
 
Last edited:

Bluesey

New member
Joined
Jul 18, 2001
Messages
232
The neck volume pot reads real low, 2.6K ohms. It doesn't look like it's been messed with but you never know. Listen, thanks for the help. I'll just be careful when I replace everything.
 

BrianGWN

Great 'Double White' North ~ Electronics Specialis
Joined
Jul 15, 2001
Messages
1,401
2.6 Kohms? :wtf
I rather expect most of the production LPs through the 1990s used 300K volume pots and 500K tone pots, the closest thing I would have looked at is a LP Classic from 1995 and it had them. With the pickups installed you should get a reading at the volume pots close to the reading of the pickups, should see about 8K or so for the 496R neck pickup and up around 15K for the 500T bridge pickup.
There's nothing going on that should cause a reading around 2.6 Kohms. Keep digging, if all else take all the electrics apart so you can measure each pot and pickup individually.

Also, as to another dumb source of hum, check the wiring that runs from the control cavity to and from the selector switch. In the modern times they use a four conductor cable, white and red wires go from the volume pot outputs to the selector, black and green wires are the return from the selector to the output jack. A problem I have seen with some LPs is that someone FORGOT to connect the shield of the four conductor wire leaving all the wiring effectively unshielded. If the bare ground wire of the four conductor cable has been cut even with the outer insulating jacket (seen that!), remove an inch or so of the insulation to get at the bare ground wire, splice in another piece of wire if necessary, but make sure that ground wire connects to a ground point in the control cavity ie. where the green wire ends up on that intermediate terminal strip.

:*#$%
 

Bluesey

New member
Joined
Jul 18, 2001
Messages
232
I am going to replace the pickups, pots, and caps. My questions now are, how do you ground everything without creating any ground loops? Right now all the pots are on a metal plate. Do I have to reinstall that plate or can I ground it another way? Also should I change all the wiring to be sure there are no suspect wires?
 
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