Metropoulos Forum

i just replaced the icar pot in my late 60's/early 70's vox wah. it say 100k on the pot. however, i checked it with a mutlimeter and measured 500k. has anyone else found this?

They tend to drift up over time and I think how much usage it has seen . I have two old Vox wahs, ICAR in one measures 190K ohms and the other 290K

Mine measures 241k (it says 100K on the pot like yours)...

wow. thats nuts. it never even occurred to me that it could have drifted that much.

Carbon resistors can drift up over time as well . Usage wears the resistive carbon track which IIRC will also contribute to this increased resistance. Notice that some of the replacement ICAR pots are 200K to replicate an old used wah pot.

I resume this long gone post to discuss with you about old icar pots. I've got one of the first clyde mc coy wah from 1967 it has epoxy on the circuit to hide it. It works but the pot is a little scartchy. So i bought a replacement from Rmc. Then i replaced it and measured... Well it drifted to 6.2 M!
When i replaced it with the rmc one.. The wah didn't work well. The effect was very weak.. So i don't know what to think.
My thec told me that according to him it was way more than 100k till the start. Maybe 2or 3 M. It was written 100k to create confusion.

6.2 M ! Sounds like the pot is shot. Good to grab a few to try , tapers seem to vary...

I re istalled the icar one.. Amd the sound is there! Jimi for sure!
I don't understand ...

Fever Dog wrote:i just replaced the icar pot in my late 60's/early 70's vox wah. it say 100k on the pot. however, i checked it with a mutlimeter and measured 500k. has anyone else found this?

What did your wah sound like before it started giving you problems?

Hi the wah was wonderfull but the scratchy pot..

In that case may be there is an option to clean the pot? Sounds stupid for a 45 years old pot, but there is always a hope

I ask because maybe that famous sound we are after is truly coming from the 500k pot and not the the so called 100k.

axeman wrote:I ask because maybe that famous sound we are after is truly coming from the 500k pot and not the the so called 100k.

I think the same thing... How is that with 200k the wah doesn't sound a t all!??

Can you post some pics of this wah with a 6.2 M ohm pot?
Wah does not need all that range of a pot, It uses actually some small portion of the "trace" of the pot. May be the 6.2 M Ohm pot is a special LOG type or something like it, and when the Wah at max, you get only like 200k-300k of a resistance? Can you check the resistance when the wah on the max?

6.2M seems me crazy (or shot), possibly you measured in the wrong way? did you measured when the pot was desoldered and alone?
BTW, yes, it's normal for them to drift from nominal 100K to two or three times..mine (68) is around 300k, don't remember exactly.
Unfortunately it is also normal for it to be a bit scratchy..all of them are like that more or less..it's something you have to live with, like the presence pots of marshall. That is due to design of the carcass which leaves too much gap and dust enters too easily in the traces. Surely you can clean it , but after 2 or 3 weeks it starts back again. I dunno if there are some tricks to mitigate that.
I have tried too to replace it with aftermarket pot (200K), no scratch, but in noway it sounds the same anymore ..sounds weakier, just like you said. Poor us vintage nuts!