Issues with multiple PSU's

[TimMJN]

The quest continues…

DIY Power Supply Thread - Questions and Help

Well, I spent the better of part of today rewiring and testing my PSUs. There’s no solution (yet), but I seem to be getting closer to the cause. I started off by taking out the 2/3 PSUs, and properly wiring the remaining one with 1.5mm^2 wire. After hooking up the scope, this is what the 12V supply rail looks like: [2021-09-04 14.26.23] As can be seen, there’s a ~30mV 50Hz ripple on the supply. There’s also an opposite ripple on the negative supply. I ran some tests by plugging in a sequence…