[chbot] Earth issues

[Marshland Engineering]

Ok not Kaiakora type but electrical ones.


I have a digitally controlled soldering iron, PSU and Scope. For the past XX
years, I never connected the scope earth to the plug earth thinking that the
probe ground would therefore float with reference to my power supply earth. 

Any way, when soldering components on my test PCB, a few LED's started to
glow. I measured the voltages on the test equipment and I had 90 volts between
my soldering iron and scope probe earth. A few more measurements and I found
scope probe earth was the problem. 

What is normal? Earth the scope, disconnect all cables to the board before
soldering, run an isolating transformer?

Often USB powered boards get supply from the PC and some laptops only have 2
pin plugs so all sorts of earth issues can occur? 

Any suggestions ? 

Just ordered a battery pocket scope from Aliexpress. That will solve one
issue. 

Cheers Wallace.