Vintage Synth Repair

Hi,
Typically the 4th lead is a center connection half way
between the pot full clockwise and full counter clockwise.
The idea is that you could connect this to a ground or voltage
and it would be an absolute center point in the pot's rotation.

In the case of Peavey, I believe they used them for circuit board 
mounting stability so that when you secured the pot to the panel
the circuit board was also secure.

Hope this helps.
GD



--- In vintagesynthrepair@yahoogroups.com, scott frye 
<painintheamp@...> wrote:
>
> I have some 4 lead pots for peavey amps. The 4th lead goes 
nowhere. Why would peavey would buy this ALPS pot for amp when the 3 
leads for fine??
> 
> Scott  Frye
> AudioFixation
> Consumer / Pro Audio Repair
> Southern VT 
> 
> "Resistance is futile but.....
> Impedance is much more complex"
>