powerampfreak schrieb:
I was given an oscilloscope, a Fluke PM3082 from a retired industrial
electronics engineer.

....

The mains fuse has really exploded. Shattered glass in the fuse
holder. A brief examination of the primary side of the smps reveals no
shorts. The smps is an ordinary flyback supply. Mains rectifier ok,
switch ok, snubber, line filters all ok. Really don't know why the
mains fuse went.

Once the SPS of a notebook computer made the mains circuit breaker
(16Amps) interrupt, while I connected it to an outlet. Big bang, arcs
and stuff.

It turned out, that one, maybe two, diodes in the rectifier was open
afterwards. The SPS is still working on 220V, on 110 probably not.

HTH,
Falk