Take a look and see what you think this might be. (Schematic attached).
https://youtu.be/-PJO9xfy4Ps
1. The low freq ripple/noise is still apparent even when quickly disconnecting the PSU cable as the unit cools off for a few seconds. This makes me believe it is not the PSU itself, which is a basic RCRCRC design.
2. It increases and decreases with gain rotary switch.
https://youtu.be/-PJO9xfy4Ps
1. The low freq ripple/noise is still apparent even when quickly disconnecting the PSU cable as the unit cools off for a few seconds. This makes me believe it is not the PSU itself, which is a basic RCRCRC design.
2. It increases and decreases with gain rotary switch.