Yeah the buzzing/humming is normal that's why commodore used to fill the old brick psu's with epoxy resin it put a stop to the buzzing
but a lot of them overheated as a result and the epoxy made it impossible to replace the caps and regulator
Jeff-20 wrote:Wow, I never understood that whole epoxy thing. Honestly, I hadn't given it much thought, but I am now glad to know why they did that.
I can't find the quote at short notice, but I recall the comment from Bil Herd (C128 / C264 design engineer) that "It was very hard to set fire to a big hunk of epoxy".