Tone pot malfunctioning?

PoopSoupGuitars

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Hi guys,

Hoping for a bit of assistance with wiring.

I've just finished a Tele build with a humbucker in the neck, single coil bridge, with a 3-way toggle switch instead of the standard blade style.

I followed the wiring diagram below previously posted by @Peegoo on an old thread I found:
1670070093587.png


Having a couple of issues. The guitar plays, and the switch seems to be working correctly. However the pots/control knobs are not working as I would expect. Volume at lowest position still plays sound, a the tone pot is acting very weird. Tone at its very lowest does go muddy as expected but moving it even a fraction goes full bright. Also, moving the tone knob at all causes cut outs in the sound.

I'm sure this is down to bad soldering, but I wondered if anyone can help me pinpoint given the info above?
 

PoopSoupGuitars

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Sorry just to add some additional information:
1. Both pots are brand new (A500K and B500K)
2. I have a ground wire running from the bridge plate to the back of the tone pot (that's not on the diagram but I believe it's necessary?)
3. The ground for the output jack is going to the back of the volume, not the tone as shown on the diagram. I don't think it matters but correct me if I'm wrong)
 

Peegoo

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@PoopSoupGuitars

1. Do you have a short jumper wire connecting both pots' cases? If not, add one.

2. Do you have the pot's tabs properly connected? Should be like this:

Vol pot
-Tab 1 grounded to pot case
-Tab 2 connected to tip of output jack
-Tab 3 connected to switch AND Tab 1 of Tone pot

Tone pot
-Tab 1 connected to Tab 3 of Vol pot
-Tab 2 connected to one leg of capacitor; other leg connected to pot case
-Tab 3 floating (connected to nothing)

Remember: pot tabs are numbered like the back of your hand: hold up three fingers, and there ya go.

Pot-Back-Peegoo-123.jpg
 

sjtalon

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Is the outer volume pot terminal grounded?

Are they on a metal control plate? Then you don't really need a jumper.

You may have fried one or both pots soldering on them, or have a bad one?
 

Peegoo

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Yes, the bridge ground connected to either pot case works fine.

And the ground to the output jack can be connected to the case of either pot.
 

PoopSoupGuitars

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@PoopSoupGuitars

1. Do you have a short jumper wire connecting both pots' cases? If not, add one.

2. Do you have the pot's tabs properly connected? Should be like this:

Vol pot
-Tab 1 grounded to pot case
-Tab 2 connected to tip of output jack
-Tab 3 connected to switch AND Tab 1 of Tone pot

Tone pot
-Tab 1 connected to Tab 3 of Vol pot
-Tab 2 connected to one leg of capacitor; other leg connected to pot case
-Tab 3 floating (connected to nothing)

Remember: pot tabs are numbered like the back of your hand: hold up three fingers, and there ya go.

Pot-Back-Peegoo-123.jpg

Thanks for the response Peegoo,

1. Yes both are connected by a wire. I am using a back control cavity instead of the standard Tele front and the whole cavity is also lined with copper tape.
2. So Tab1 on vol had not been grounded correctly. I had bent it back on itself and soldered but it didnt reach the actual pot case (lugs must be shorter than average. I have now just added a short wire from lug to case. All other lugs appear to have been setup as you've described.

I was hopeful that the mistake above was the fix but still having the exact same issue now. I cleaned up some soldering when in there and the cut outs are now gone with tone adjustments.

I believe the only outstanding issues now are:
1. Volume doesn't go to 0.
2. Tone is binary. Total mud or high bright. It's not sliding up as it should
 

Peegoo

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How is your soldering? Are you using a minimum amount, or do you have big blobs? Big blobs can cause solder to flow into the pot and make it act strange. Also, big blobs can overheat the pot and either partially kill it, or kill it completely. Same goes for the tone cap: you can kill it with too much heat.

Post some clear close-up pics of your circuit. Without that visual reference, we are just guessing.

And don't worry if your soldering is not pristine...most all of us start out by learning to solder on our first project guitar.
 

Peegoo

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*Hides under desk in embarrassment*

Very new to soldering. Colour of wires can be ignored...

Do not be embarrassed...we all started somewhere and we all had solder jobs that look like this. Anyone that peacocks here about it can shove their soldering stick where they know they won't like it.

Your wiring looks like it's connected to where it needs to go. I think the problem may be that you either have solder inside the pot(s) and you my have cooked the capacitor.

I think the thing to do would be to unsolder everything, use a solder sucker or desoldering braid to clean up the solder, and then test each pot for proper operation to confirm it's working as it should (smooth sweep all the way around).

Not all meters have the ability to check capacitance. If yours does, test the cap too. If not--get a new cap.

When you restart, do the following to make your soldering a little neater:

1. Use a hotter iron. I know this sounds backwards, but a hotter iron means you are applying heat for a second or two to make the connection. An iron that's not hot enough causes you to spend too much time dumping heat into the connection and you cook the parts.

2. Use a 'heat sink' between the connection and the component--especially the cap. A heat sink is a small crocodile clip or hemostat that catches all the heat before it can reach the component. It prevents heat damage to the component.

Soldering-Heat-Sink.jpg


3. The other thing to do when making a new connection is to 'tin' each part before joining them. This means to heat the wire or solder tab and apply a little solder to it. This way, connecting the parts involves putting them together and simply applying heat for a second or two; the existing solder on both parts melts and fuses them together, with no need to add more solder.

Using your parts to reassemble, there will be no need to tin the connections because they'll already have solder on them.
 

AAT65

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More good advice from Peegoo above! Have you got a multimeter? IMHO you should have one to check continuity when doing any soldering.
In particular check you have a good connection for every ground - all the way back to the jack ground. It should be less than a 1ohm resistance.

You can do a quick test on pots in-circuit: you wonโ€™t see the 500k resistance but you should be able to measure very low resistance when the volume pot is one way and (almost) the pickup resistance when itโ€™s the other way.

You can also do a very crude check of a capacitor using a resistance measurement on your multimeter โ€” when you first put the probes on each end of the cap you typically see a low resistance reading which quickly shoots up to OL or whatever your meter calls an open circuit. Swap the probes around and it will do the same again. (This is because you are charging the cap up, so some current flows initially.) Not as good as a proper test but it can give you some confidence in the capacitor.
 

Boreas

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I'm sure this is down to bad soldering, but I wondered if anyone can help me pinpoint given the info above?
PoopSoup could also describe the ground solder blobs on the back of those pots. The untidiness of it doesn't concern me as much as the black deposits floating around on them. Are the deposits molten black plastic, from scorched flux, or just a dirty tip? If it is from being scorched, it is unlikely, but possible, that the pots are damaged (roasted) from heat. Could you have used excessive heat?
 

Boreas

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Do not be embarrassed...we all started somewhere and we all had solder jobs that look like this. Anyone that peacocks here about it can shove their soldering stick where they know they won't like it.

Your wiring looks like it's connected to where it needs to go. I think the problem may be that you either have solder inside the pot(s) and you my have cooked the capacitor.

I think the thing to do would be to unsolder everything, use a solder sucker or desoldering braid to clean up the solder, and then test each pot for proper operation to confirm it's working as it should (smooth sweep all the way around).

Not all meters have the ability to check capacitance. If yours does, test the cap too. If not--get a new cap.

When you restart, do the following to make your soldering a little neater:

1. Use a hotter iron. I know this sounds backwards, but a hotter iron means you are applying heat for a second or two to make the connection. An iron that's not hot enough causes you to spend too much time dumping heat into the connection and you cook the parts.

2. Use a 'heat sink' between the connection and the component--especially the cap. A heat sink is a small crocodile clip or hemostat that catches all the heat before it can reach the component. It prevents heat damage to the component.

Soldering-Heat-Sink.jpg


3. The other thing to do when making a new connection is to 'tin' each part before joining them. This means to heat the wire or solder tab and apply a little solder to it. This way, connecting the parts involves putting them together and simply applying heat for a second or two; the existing solder on both parts melts and fuses them together, with no need to add more solder.

Using your parts to reassemble, there will be no need to tin the connections because they'll already have solder on them.
Another thing I always add to Peegoo's above dicta is DO NOT USE LEAD-FREE SOLDER. And always keep your tip CLEAN and TINNED. If you are going into production from a poorly-ventilated closet, then you can buy a set-up to use lead-free solder effectively. But for us kitchen table electricians, good ol' lead/tin solder is the way to go. Just don't use it to stir your coffee.

I agree with Peegoo's assessment and plan. Either use a sucker or braid to remove any dirty or excess solder and start over. When everything is disconnected, check to make sure the pots are working properly and smoothly. Then resolder using pre-tinned wires and terminals.

One thing Pee didn't mention is heat vs. mass of the soldering tip. This can be personal preference, but for guitar wiring I prefer a chisel tip (not a point) that has more mass - which equates to faster heating of the components at any given temperature. I believe this is called thermal capacity. If it is taking more than a second or two to melt your solder, reassess what is going on. This is critical to a good joint. If your tip is up to temperature, clean, and properly tinned, a second or two on the joint is all you should need. If you are sitting there for 5-10 seconds and the parts are smoking and everything is melting BUT the solder, you need to practice some more on cheap parts.
 
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Peegoo

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^^^ Leaded solder is a good thing. I like BigClive's description of it as being "juicy" compared to the lead-free type, because it does flow better and makes cleaner connections.

Do not believe any goober that claims soldering smoke contains lead 'vapor', because the soldering process does not heat the lead to its vaporization point; the temperature is too low.

That smoke is rosin flux boiling off. While it's not poisonous, it's like any particulate matter that you inhale: it's bad for your lungs.

You can get lead residue on your fingers from handling solder and electronics, so wash yer hands when done, before eating anything, smoking a cig, etc.
 

PoopSoupGuitars

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Hey all,

So I've been playing around, resoldering etc. Firstly, pretty sure leaded solder is only available in the US these days (I'm Irish).

Anyway, after some messing, volume started working as it should! No idea which fix did it, but I got excited, closed everything up and went to play.... Now I am getting NO OUTPUT AT ALL!

Fixed tried so far:
1. New volume pot, I assumed I had goosed this one. No difference.
2. Resoldered output jack. No difference.

I do have a multimeter. I am getting no beep when I test lug 2 on Vol (output) to anywhere. I'm assuming this is the issue (even with the new pot though??). Or maybe this lug shouldn't have continuity since it's live and not a ground? (not sure if that makes any sense)
 




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