Pot issue

[fender3x]

I had a bit of a strange issue happened with a pot. I am building and ES type guitar, and the only way to fit the pots is through the F-holes. Normal sized pots don't fit, so this is the first time I'm using minis. It's also the first time I am using pots that have 24 spline shafts. I got some knobs that would fit and I put one of the knobs on one of the pots to test the fit. It fit fine, but when I tried to pull the knob off it pulled the entire shaft out of the pot.


The way the shaft is held on with most pots is by a crimp in the bottom. In this case the crimp just a broke off. I was using a CTS mini pot. The construction is a little bit different on other brands but the crimp is fairly similar.


It was fairly easy to fix because I have not yet installed the wiring harness in the guitar. I just took the pot apart and put the shaft and rotor assembly from another pot in it. Since the resistor wafer is not attached to the assembly in CTS pots I didn't have to do any re-soldering.


Has anyone else had this problem? If it happens very rarely OK. But it would be a real pain if it happened when the wiring harness was installed in a semi-hollow

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[Simon Barden]

Never come across it myself but it can't be that common or CTS would have improved the design. It doesn't take long with things like that happening to ruin a reputation in this internet age. I'd contact them and see what they have to say. They may have had a bad batch.

[fender3x]

Never come across it myself but it can't be that common or CTS would have improved the design. It doesn't take long with things like that happening to ruin a reputation in this internet age. I'd contact them and see what they have to say. They may have had a bad batch.
That's a good idea. Will send them an email.

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[Dedman]

had the exact thing happen to me on my ES build last week, I threw it away , lucky I had a couple of spares on hand

[dingobass]

Not unusual for that to happen with CTS pots.. hence my refusal to use them or Alpha anymore.
Bournes make a far superior pot IMHO.

[Andy40]

Its happened to me too. but it was my fault.:mad:

[fender3x]

Not unusual for that to happen with CTS pots.. hence my refusal to use them or Alpha anymore.
Bournes make a far superior pot IMHO.
I was sort of afraid of that. In another thread I took a bunch of pots apart, and honestly the build quality the Bournes was no better than the others.* In fact the Bournes were so identical to the cheapest no-name Chinese pots I could find that all the parts were interchangeable. The bottom line may be that the crimp in small pots is also small, and a potential weak spot. I probably would not worry about it much on an axe with easy access to the pots. CTS might even have a slight advantage since you can swap out the shaft and wiper assembly without re-soldering.

But on a guitar where access is hard I will probably just avoid the minis altogether, and use sold shaft pots.

That does not help with my PB ES though...The only access to pots is through the F-hole and only the minis will fit. Even if I were confident of the Bournes, I could only get the values I needed in CTS, and all the minis seem to have split shafts...

So I ordered some of these...

https://www.allparts.com/EP-0220-008-Pack-of-5-Brass-Pot-Sleeves_p_1290.html

...And some knobs with set screws

Hope they work OK. I don't want to be pulling on a knob if it might result in major surgery.

* BTW there were differences between the Bournes and the cheap-o pots. The values of the cheap-os varied a lot from pot to pot when tested with a multi meter, but the values were very consistent with the Bournes. So, I think Bournes does better QC on the resistor wafer.I should also say that the consistency was pretty good with the alphas an CTS pots too... All were better than the cheap-os. By the same token I would not trust the crimp to hold up on any of them now.

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[fender3x]

18986

Just a quick follow up... Clearly there are times when I have no idea what I am talking about.

I thought these sleeves would fit tight over the pot shaft and fit loosely inside the knob so that the set screw would be needed to hold the knob in place.

It's actually the opposite. Brass piece actually fits rather tightly inside the knob, so, on mine, the set screw is no longer necessary. The knob can be gently pulled off or pushed on.

That's not as good as I had hoped for, but since I am pretty much stuck with minis and stuck with CTS for this build, I'll probably use the sleeve and set screw knobs. They are much easier to pull on and off than the ones designed for split shaft so when I do end up having to take off the knobs it won't take quite so much force and will be easier on the crimp.

I have two fender electrics--six CTS pots in all. They are all going strong with just the occasional dash of lubricated contact cleaner. My ASAT has some more. One is over 20 years old and going strong. How the mighty have fallen if this is now a common CTS problem!