4 ms·
> We had to be careful about those AC utility jacks. The tester ground was at -11 volts at several hundred amps. If you clipped a scope to a ground, it would ha
by jandrese 2y ago
> We had to be careful about those AC utility jacks. The tester ground was at -11 volts at several hundred amps. If you clipped a scope to a ground, it would happily melt the insulation off the scope probe until it stunk up the room and pooled on the floor. We had to use a three-prong adapter with the ground cut off.
You don't get this kind of excitement anymore with modern electronics.
- fortran77 2y agoI have the same issue today when I fix old tube radios. Once side of the mains is connected to chassis -- and there are no polarized plugs. I use an isolation transformer, otherwise if I try to use a scope, I'd blow it out immediately--50% of the time.
- Aloha 2y agoI am cheap. So I've never used an isolation transformer, I measure from test equipment chassis to chassis and check voltage potential, then roll the plug as needed.
- fortran77 2y agoIt also reduces the risk of shock. Spend the $100 and get one.
- Aloha 2y agoHow so?
- dave8088 2y agoAn isolation transformer will prevent electric shock should you accidentally put your body in contact with the hot side of the device and earth. https://en.m.wikipedia.org/wiki/Isolation_transformer#Electronics_testing https://en.m.wikipedia.org/wiki/Isolation_transformer#Electr...
- formerly_proven 2y agoAn isolation transformer also completely prevents a GFCI from working.
- deleted 2y ago[deleted]
- stephen_g 2y agoNot exactly this, but you can easily make big sparks and trip RCD (GFCI) breakers if you accidentally probe something with a grounded scope that isn't isolated. In the past we've used battery powered scopes to get around this (cutting the ground pin off anything isn't a good way to do things!)