Oscillator Range and Frequency Check

1. Turn on OSCILLATOR-1 and set WAVEFORM to Triangle, RANGE to 2'.
2. Ensure PITCH wheel is centered and TUNE/FREQUENCY controls are at 0.
3. Apply a -30dB, 3520Hz sine wave to the INPUT EXT. SIGNAL jack.
4. Set CUTOFF FREQUENCY to +4. Turn on EXTERNAL MIXER switch.
5. Adjust level for -10dB at the EXTERNAL INPUT VOLUME control.
6. Turn on OSCILLATOR-1 MIXER switch. Hold high 'A'.
7. Check for zero beat (silence) between the internal oscillator and the external tone.
8. Repeat for Oscillators 2 and 3.

Source: MINIMOOG — minimoogservicemanual (manual)