As the title says… I have a 1981 Realistic Moog MG-1 that has recently started drifting pitch on Tone Source 2. It has been cleaned of the infamous black “tar”. My tone source 1 has never worked since owning it but the most debilitating problem at the moment has been the recent drift in pitch. It drifts slowly flat as I strike a key. It only does this on tone source 2. It does not have this problem on the polyphonic setting. Someone please help. This little synth is my bass machine!
And you never thought of trying to have it fixed all this time ?
As for pitch drift, it seems like the pitch CV sample-and-hold might be defective (U7A in the Keyboard Glide part of the circuit). Better have a qualified tech have a look at it. Or better yet, get yourself another working MG-1. They can still be found for not a lot of money.
BTW, the polyphony section is separate from the monophonic one, electronically.