I picked up what I believe is an older 230v G6 frame. The NT12 PSU says "REV 2" on it.

I noticed the PSU hums slightly. Though I also noticed one of my other G6 frames sounds
about the same. But a third NT12 frame I have is quieter. So I just thought I'd ask if it's a
concern.

The other thing I noticed was the plug socket has no hardware for a fuse. Is that the way
older units were made or is it someones replacement