MS-20 Mini tune and scale adjustment
I sometimes have to re-tune my MS-20 Mini. The pitch scaling is incorrect, and has to be adjusted. Sometimes on both oscillators. To do this I set up a tuner next to the speaker and start playing octaves. I turn the scale trim pot until the octaves are clean, and then I move it to the correct base pitch with the tune trim pot.
Usually I just poke at the trimpots until I find the correct ones but the last time I did this I wrote the numbers down:
PT3 - tune osc1 PT1 - scale osc1 PT5 - tune osc2 PT4 - scale osc2
The trim pots are located on the back of the board that sits under the panel and are easily accessible by just removing the back panel.