Help me identify this circuit?

[VolksWilliam]

Ok so I ended up with a box of amp and pedal parts. (Long story).

In it was this:





Just seein if anyone can help identify it. Green wire is labeled in. Yellow is out. Black and red are + and -
Not sure about the grey wire. Tried hooking up a battery and a keyboard and an amp but nothing but buzz.

Thanks guys!

[rousejeremy]

Looks like something that would get mounted in a guitar. Volume or Mid boost? Take a pic of the bottom of the PCB, and under the pot.

[Devius]

Seeing that it needs power, its probably something similar to the emg afterburner. The length of the threaded shaft on the pot would be a good indicator if it was meant for a guitar.