There are several reasons why your Roland Sh-101 could be defined:
Temperature: Analog synthesizers, such as SH-101, can be affected by changes in temperature. If your synthesizer is exposed to extreme temperatures, this can affect the tuning.
Age: The SH-101 is a vintage synthesizer that occurred in the 1980s. Over time, electronic components can wear down and affect the tuning.
Calibration: If the synthesizer calibration is not configured correctly, this can affect the tuning. Calibration can deviate over time, so it is important to verify it regularly. Give good maintenance to your
trucks for a good functioning.