MXR EF M82 - no sweep - only clean - without mods

[HitTive]

Hi,
I have problem with MXR EF M82 from tonepad: http://tonepad.com/project.asp?id=4 .
When I set both potentiometers on minimum i have clean sound. When I turn up treshold sound is distortion and hiss.
Maybe someone know where i can find measurement of voltage on ICs?
I use NXP IC.