How old is the wiring in your house???? If you have a GFCI protected socket plug your scope into it and see what happens. If the scope is screwed the GFCI will trip intermediately. You might not even have to turn it on to trip the GFCI.So I have concluded it has to be the scope. I have an old tektronix 465b. I hooked up to good wall supply. Fixed the burnt out radio it was running and lights working. Hooked up to scope through rf sampler and guess what????? Smoke starting billowing out. Something is seriously f-ed up with the scope is my conclusion.