Hi,
I have a problem with my Little Phatty Stage II. Sometimes the knobs are adjusting themselves without me touching them! It happens when I’m not in our studio - downthere there’s no problem. I really can’t figure out what the issue seems to be. It’s not a problem as long as the Moog is just powered but as soon as it is connected to a mixer the knobs starts rotating by themselves.
I really hope someone out there knows what is happening to my Moog!!!
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I think this is a grounding problem. I remember it can happen in Denmark cause there’s no ground connection.
Maybe I’m wrong…
It can happen anywhere there is a faulty ground connection, or if the Phatty is plugged in to gear in such a way that it causes a ground loop. It sounds like your mixer is causing a ground loop.
Right, but I remember in Denmark there’s no ground connection as it is usual in the States or in most other countries.
Rudi, he says that the problem goes away in the studio, and only occurs when the LP is plugged into a mixer. Unless the studio is in another country, I think the problem is a ground loop. You could be right, though. 
Of course it’s also depending on what’s connected to the LP.
The OP never said anything was connected to the LP, but you’re right, of course, Rudi. 
Yeah and that’s exactly the problem: if only a headphone is connected and the LP is running without a ground connection you will get strange things too. Both situations (ground loops or no ground connection) produce problems 
@Lars: a tech should make a ground connection from the secondary side of the power supply to the cabinet. This helps normally.