A litany of dumbassery

[TimMJN]

@zorch, I took this over to the PSU thread:

DIY Power Supply Thread - Questions and Help

So last week I upgraded my case’s PSU, from 1x FC microbus and some passive bus boards to 3x FC routemaster. Much to my unpleasant surprise, I got presented a nice fat 50Hz hum after reassembling the whole thing. I noticed the hum emerged whenever I plugged two modules from different PSUs into eachother, so my immediate thought was: ground loops. I also unplugged each individual module to see whether one of them was giving problems, but no difference there. Here’s a scope capture of a VCA with …