Wiring Problem: tone knobs act more like a switch

kezian

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The wiring on my 1971 strat was unoriginal, and not functioning, so I decided to aquire NOS parts and get it back to full originality. I sourced the right 3-way CRL switch, the right tone cap, and the right date codes on the pots. So I replaced the pots and redid the wiring on my strat, and have encountered the following problem. The result on the tone knobs is no change in tone(to my ears) from 10-2 then a big loss in highs on 1. Is it the taper of the pots? The seller said they are NOS audio taper 250k.

The thing is, the first time I bought pots from this seller, he sent me some pots that did not turn all the way off (apparently this is a thing?) The volume never went all the way off. This drove me crazy until I sent them back and he sent me these. Now my volume works (albeit a big change from 10-8 then slowly after) but the tone knobs dont really work.

Is there a chance that the capacitor is the issue? or something in my wiring.

I have tested and all the pots are grounded to each other (via the foil)
 

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E.T.

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Could be the pots. If you have a multimeter it's worth checking with the leads on the middle lugs and the ones with the tone cap on them to make sure the resistance is actually changing as you rotate them. If the tracks inside are damaged or the wiper has collected dust which gets picked up/dropped off at one point along them you'll see infinite resistance until you get down to 2 then suddenly they'll show low, and then zero once they're all the way off. Audio taper drops off fast and then slower, so you should probably be hearing more of a change between 10 and 8 than between 2 and 0.
 

LtDave32

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Make sure one lug of the volume pot is grounded to the pot case or it can cause all kinds of odd stuff to happen.
 

calieng

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I do not see anything wrong with the way you have wired it.

My first guess is a damaged pot. Even new ones can sometimes be defective. Sounds like the carbon ring is cracked inside the pot.

Second guess is poor grounding from the foil but likely would not produce the results you mention. BTW for $6 an aluminum shield is much better to add on.


I suggest trying a different pot.

Good luck.
 

kezian

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heres the thing, its both of the tone knobs while the volume knob works fine ... i cant imagine the odds that one out of three were working and i happened to pick that one to be the volume knob
 

calieng

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heres the thing, its both of the tone knobs while the volume knob works fine ... i cant imagine the odds that one out of three were working and i happened to pick that one to be the volume knob
Tone pots are $5 or less. So spend the $10 and put in 2 new pots and see if they work. Then you will know if it is the pots or not. You likely got 2 bad pots. Maybe being NOS the contacts are dirty or they have been sitting somewhere where they were contaminated or damaged over the years.

If it was capacitor or wiring it would not do anything at any setting but since it does work at 1 then it is dirty contact, broken carbon ring or whatever with both pots.
 

Dilver

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If it were me, I wouldn’t worry so much about the pot being period correct and just get a new pot that functions the way it should. Pots can get cooked with too much heat.
 

D'tar

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I would reflow this conection at the pot as it is one common connection for the two pots along with the final cap to pot casing joint which may need attention as well


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GermHerm

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I assume it onenof the pots. I never care about vintage correct pots. I would buy new CTS and give the a trial.
 

Duane.S

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heres the thing, its both of the tone knobs while the volume knob works fine ... i cant imagine the odds that one out of three were working and i happened to pick that one to be the volume knob
Since it is happening on both tone pots, the common link is the cap. I can't think of how a cap could cause the problem you describe but I'd say to try a different one.
 

calieng

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Seems the most likely, I'll give it a shot!
I did have a problem with a volume pot in a Les Paul only partially working. When I checked it the tab that should be grounded was just pushed against the pot case but not soldered. When I soldered it the pot worked fine. So who knows some bad grounding or solder connection could indeed be the problem...

Good luck
 

GBLEV

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I've experienced crappy, or defective, capacitors that do not work too well in conjunction with the pot's taper. Not all caps are/were created equal. Since this is very simple to swap, I would start there and try out a different capacitor. If the problem still exists, then you know your problem is elsewhere. Good luck!
 

the great waldo

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If it's sounding crappy in all positions it's probably the pots(double check your earthing) What you can also check is shorts on the pickup coils to the magnets. Usr your multimeter in the 5-20k ohms setting and check from black Usually to each E string magnet Bass and High e's. if you get a reading then youv'e got a short on the magnet . Not a drastic problem but can causew troubles. I've noticed youv'e not run a seperate eart to the backs of the tone pots (vintage correct) so you might be getting a bit of resistance between the pot case and the screening foil via the toothed washer. Check the resistance between pot backs and earth . It should all be 0 ohms.

Cheers

Andrew
 

the great waldo

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Just one more thing if the switch is old the contacts might have oxidized causing problems. Just a thouhgt
 


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