Tempco resistors old oscillator board

Tips and techniques for Minimoog Analog Synthesizers
Salomonander
Posts: 20
Joined: Wed Aug 07, 2024 9:47 am

Re: Tempco resistors old oscillator board

Post by Salomonander » Thu May 22, 2025 1:35 pm

And one more issue :( When playing the highest register, only oscillator 3 is clean. Oscillator 1 and 2 (1 especially) have sone low frequency dirt. Sounds as if some real low notes get triggert. The low frequency dirt does change pitch with the keyboard. I dont know how to explain it better. I could record it. Any ideas what this might be?

johnstaf
Posts: 14
Joined: Sat Aug 15, 2020 12:45 am

Re: Tempco resistors old oscillator board

Post by johnstaf » Mon Jun 16, 2025 6:40 pm

I wonder if the voltage sense lines are causing the noise. These lines often caused more problems than they solved and weren't necessary to the proper functioning of the synth, so Moog eventually connected the voltage and sense lines in the oscillator board. This can be seen in the service manual schematic.

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