New Volume Pot Crapping Out?

[uiah]

Hi,
​​​​​​​I recently replaced all of the pots in my Les Paul, but now the bridge volume is cutting in and out when i move it kinda like a bad jack that you have to wiggle to get sound other than horrible noise.
Is it possible i damaged the pot with too much heat or more likely a bad solder? Is there a way to test with multimeters?
Any help is much appreciated...

[newey]

May 18, 2021 1:00:04 GMT -5 uiah said:

Is it possible i damaged the pot with too much heat or more likely a bad solder?

It is easy to damage a pot with too much heat. I avoid grounding things to the backs of pots for just that reason. If you do have to solder to a pot back, use something as a heat sink.

However, usually when a pot is fried, you'd get nothing rather than an intermittent problem. It can be tested with a multimeter but you will probably have to desolder it and remove it to test it accurately, probably easier to just swap it out if you have another pot available.

With an intermittent type of problem, the ordinary ways we test stuff wihtout removing it (i.e., by using a meter across a guitar cable plugged into the guitar) won't work since you would never know if moving the control was showing a problem with the pot, or just joggling an intermittent connection.

[unreg]

uiah, 1.) is that a bare wire, tinned at the end, soldered to the back of your pictured pot? Since newey just said that destroyed pots won’t ever produce good sounds, and your pot sometimes produces good sounds, maybe that bare wire is causing extreme noise? {see newey’s post below}

2.) When soldering a wire to metal it is wise to have a “third hand”, an alligator clip device, hold the wire to the metal and then you simply cover the wire with solder. It seems that wire was pressed down into the solder glob. Poor solder connections do cause noise too.


FINAL-EDIT: You can use a multimeter to test your solder connections.

a.) Set your multimeter to measure Resistance.
b.) Clip the cables on either end of the solder spot, maybe clip one of the cables to one of the lugs {see my post below} and the other cable to the bare wire.
c.) If your multimeter returns a value super close to 0.0 ohms, then the tested spot has high conductivity. In my experience, any value of a measured ground solder above 0.2 ohms has been a noise problem

d.) Regardless, if that is indeed a bare wire, please replace it with a shielded wire. Your body alone gives off electrical interference. Electrical interference is bad noise source; the covered wires are (somewhat?) shielded from electrical interference. {sir newey states that bare wires are perfectly fine to transmit ground}

[unreg]

May 18, 2021 10:53:26 GMT -5 unreg said:

maybe clip one of the cables to one of the lugs and the other cable to the bare wire.

Woh woh woh! I’m sry, I’m sure the lugs are NOT connected to the pot case (they can’t be… that’s why it is necessary, for your setup, to solder lug1 to the case for ground); therefore just clip one of the cables to the bare wire and hold the other cable touching the pot shell.

So sorry… hope I didn’t cause you a lot of wasted effort.

[guitarnerdswe]

Looks like a CTS by your picture. Yep, I've had several new pots act like that. One of the reasons I don't use them anymore. CTS are just crap in general nowadays.

There's a reason Tom Anderson has stopped using them. John Suhr would also swap them for something else, if customers didn't simply demand to see CTS pots in a high end guitar (his words).

[uiah]

May 18, 2021 5:22:55 GMT -5 newey said:

May 18, 2021 1:00:04 GMT -5 uiah said:

Is it possible i damaged the pot with too much heat or more likely a bad solder?

It is easy to damage a pot with too much heat. I avoid grounding things to the backs of pots for just that reason. If you do have to solder to a pot back, use something as a heat sink.

However, usually when a pot is fried, you'd get nothing rather than an intermittent problem. It can be tested with a multimeter but you will probably have to desolder it and remove it to test it accurately, probably easier to just swap it out if you have another pot available.

With an intermittent type of problem, the ordinary ways we test stuff wihtout removing it (i.e., by using a meter across a guitar cable plugged into the guitar) won't work since you would never know if moving the control was showing a problem with the pot, or just joggling an intermittent connection.

Thanks very much for the input!

[uiah]

May 18, 2021 15:08:12 GMT -5 unreg said:

May 18, 2021 10:53:26 GMT -5 unreg said:

maybe clip one of the cables to one of the lugs and the other cable to the bare wire.

Woh woh woh! I’m sry, I’m sure the lugs are NOT connected to the pot case (they can’t be… that’s why it is necessary, for your setup, to solder lug1 to the case for ground); therefore just clip one of the cables to the bare wire and hold the other cable touching the pot shell.

So sorry… hope I didn’t cause you a lot of wasted effort.

All good, hadn't got around to trying anything just yet, thanks very much for the input and detailed response!

[uiah]

May 18, 2021 10:53:26 GMT -5 unreg said:

uiah, 1.) is that a bare wire, tinned at the end, soldered to the back of your pictured pot? Since newey just said that destroyed pots won’t ever produce good sounds, and your pot sometimes produces good sounds, maybe that bare wire is causing extreme noise?

2.) When soldering a wire to metal it is wise to have a “third hand”, an alligator clip device, hold the wire to the metal and then you simply cover the wire with solder. It seems that wire was pressed down into the solder glob. Poor solder connections do cause noise too.


FINAL-EDIT: You can use a multimeter to test your solder connections.

a.) Set your multimeter to measure Resistance.
b.) Clip the cables on either end of the solder spot, maybe clip one of the cables to one of the lugs {see my post below} and the other cable to the bare wire.
c.) If your multimeter returns a value super close to 0.0 ohms, then the tested spot has high conductivity. In my experience, any value of a measured ground solder above 0.2 ohms has been a noise problem

d.) Regardless, if that is indeed a bare wire, please replace it with a shielded wire. Your body alone gives off electrical interference. Electrical interference is bad noise source; the covered wires are (somewhat?) shielded from electrical interference.

That wire is the string ground and I basically just copied what was going on with the original pots. It was a bh to get off the original pot and there was more ground noise after I changed them so you could be onto something. I did press it down onto the glob - noted for next time.

Thanks again for the input.

[newey]

May 20, 2021 1:28:38 GMT -5 uiah said:

That wire is the string ground

A bare wire is fine for that as it isn't carrying signal. You can check that the string ground is good by checking the resistance between the bridge/strings and the back of that pot shell, then check it to the jack sleeve as well. But that doesn't explain the issue with your pot.

[unreg]

May 20, 2021 1:28:38 GMT -5 uiah said:

Thanks again for the input.

You’re welcome uiah! But, I’m sorry for my misguided input 😔; have edited my post again. newey knows an infinite ton about guitar wiring; I’m learning.

Note: the bad? quality of that ground connection on your pot would be a factor in the noise. So do measure resistance with your multimeter. 🙂

[uiah]

Thanks very much guys, I'll find some time soon to have a tinker...

[Deleted]

One of the questions how to test a pot.

Ohms setting
One lead on the middle lug and another lead at one of the ends.
So smooth sweep, depending on the pot log/Lin you should see the increase moving up/down.
Log will so go up/down at a quicker/slower rate depending what way your going
Lin will go move smoother half way half the value


Heat damage, I guess it is possible to damage the spindle in the middle. It is plastic. A pot is basically a old record player with the needles running on the resistance track. The big that holds the "needle" part is the weak point being made out of plastic in a metal case with a metal rod in the middle so too much heat isn't good.

Grounding can be done with a star type washer as the plate the pots hit on should be also grounded (good to ground any non used metal as electricity finds the easiest root to ground , even a bag of water with flesh around it)

[newey]

It is not just the spindle, but most of the innards of a modern pot are plastic. The resistance track is usually backed by a plastic wafer. Easy to melt one down, I've done so several times

But ordinarily, if you melt the track, you melt it away from the wiper and get no resistance change out of the pot, not an intermittent condition as uiah describes here.