Moog Music Forum

The controller knob on a Source I recently acquired only turns the parameter numbers up regardless of which way I turn it. Everything else functions fine but obviously the knob issue is quite annoying. Is this a common problem and possibly an easy fix? I have all of the specs and I was going to turn it over to a mechanical engineer friend of mine but I was curious if anyone had any tips. Thanks alot in advance!

p.s This is my first post here and I really look forward to participating in the Moog community.

The first thing to check:
the light beam sensor and dust on the LED and the photo sensor at the wheel.

Thanks for the tips! I appreciate it.

I second what Till says. I had the same exact issue on a Source I used to own, and a quick blast from compressed air fixed it.

If compressed air doesn't cure it, you may have a blown photosensor. Not only are these a bit hard to source, but when you replace the part they have to be aligned. The trick is to make sure the wheel increment/decrements evenly in both directions. I've had to do it, it wasn't hard but I wouldn't recommend this adjustment to a novice.