I built a Bugle and the power supply from half-kits several years ago and mounted them in an enclosure. They've never given me a bit of trouble till yesterday, when I selected the phono input on my pre-amp and had a loud 60-cycle hum in both channels. The loudness of the hum diminishes when I unplug the turntable interconnects but is still there. It persists after I cut the power until the LED goes dark. I've tried removing the turntable ground wire with no effect. I haven't added or re-configured anything with the system recently.
60-cycle hum is usually ground-related, isn't it?
I've considered lifting the ground wire from my mains ground but haven't yet to see if it would have an effect.
Any tips on how I should begin to troubleshoot this?
-Stott