what/where to get pot for vintage fender amp

[ja22y]

My '65 bf fender volume and treble pots are scratchy and hard to turn. What type and where can I get replacement? Also is amp's pot the same as guitar's pot? I see plenty of pots for guitar listed on the net but don't see much for amp. thx

[schmidlin]

Pots rarely go 'bad'. Clean them with some lubricated contact cleaner and see if it fixes it. If not, you probably have a leaky cap in your tone stack, likely the 250pf.

Amps usually have solid shafts and guitars are gnurled (press-on) types.

[smolder]

Pots for amps are typically solid shaft, and the knobs have set screws. Guitar pots are typically split shaft with press on knobs. Functionally the same though. You can get the right pot (they come in different resistances) by reading the spec on the schematic, or by pulling the pot, it should be marked. hoffman.com , turretboards.com, mojotone.com , amplifiedparts.com , they all have a range. You'll also need to spec audio or linear taper. The number on the pot will typically be followed by an A or an L. Be careful in there... if you have any doubt, take it to a tech. High voltage is nothing to take lightly.

[pdf64]

Yes, best trying to restore it, as most currently available audio pots have a much steeper taper (10%) than that used in BF vol and treb pots (~30%).
If replacement is necessary, Weber audio types have the best taper for this application.
https://taweber.powweb.com/store/potsord.htm
wp105A-MF
wp254A
The pot for the bass control had a 10% audio taper, so for those, regular CTS / alpha types are most suitable, available from sites listed by smoulder.
Pete.

[ja22y]

I'd prefer to try to 'restore' them instead of replacing. I did try to spray contact lubricant/cleaner. One of the pot you need to use a lot of force to turn it as if it's stuck in glue/gunk. How would you actually 'restore' a pot anyway?
Interestingly a quick browse at some of the sites, I don't see any CTS 1M 1/2W Audio solid shaft.

[mageerc]

http://tubesandmore.com/

They have them... there are 2 types, plastic shaft or aluminum shaft...

[ja22y]

http://tubesandmore.com/

They have them... there are 2 types, plastic shaft or aluminum shaft...
The solid aluminum shaft is rated 1/3W, I haven't seen any 1/2W. Is 1/3W sufficient for a volume pot? All the resistors in the amp are 1/2W or more so I'd think the pot needs to be rated the same.

[pdf64]

Well, power = voltage squared / resistance
so as we know we've got 0.33 watts to play with, and our resistance is 1000000, then voltage squared = 330000, so voltage = 574.5V
That's telling us that a 1/3 watt 1M resistor will take up to 574.5V; above that it may overheat.
The signal voltages in the pre-amp won't even reach half that, so from the perspective of power dissipation, a 1/3 watt rated volume pot should be fine.
Pete.

[ja22y]

the good old ohm's law. Thanks Pete:rockin

[Ronsonic]

what/where to get pot for vintage fender amp

Since nobody else went there yet ....

Yeah, I know a guy who's always looking to trade pot for vintage amps. But he probably doesn't want me advertising his name.

[Moddjobbs]

Since nobody else went there yet ....

Yeah, I know a guy who's always looking to trade pot for vintage amps. But he probably doesn't want me advertising his name.

^^^
So glad I wasn't the only one to think this ;)

[Ronsonic]

^^^
So glad I wasn't the only one to think this ;)

We all know this guy, shows up at gigs during breaks, comes by the shop wanting to trade repair work for some buds.

[TimmyP]

First spray a copious amount of CRC QD Electronic Cleaner into the pot and exercise the pot. If that does not free it up, as a last ditch effort, spray CRC Brakleen in the pot and exercise it. If that doesn't do it, remove the pot and soak it in (pick a solvent) overnight. If it's still useless, replace it.

[Scrutinizer]

I had to fully disassemble one of the original pots in the '64 Bassman I am restoring. The pot shaft was frozen in place. Fortunately, these old pots are really easy to disassemble.

With the pot disassembled, I cleaned the resistive element with 99% isopropyl alcohol and a q-tip, then applied some Caig MCL (http://store.caig.com/s.nl/sc.2/category.293/.f) to the resistive element, and cleaned the the wiper with Caig De-Oxit.

After cleaning and re-assembly, it feels and works like a new pot.