(..)
Or have a functional brain!
Unless you have gone through all the fast changes in the
mid 70s/80s when "SOLID STATE" became available and
really fast the VLSI was introduced...
Unless you had lived that changes forcing you to adapt
your methods and procedures and instruments... you will
not realize how easy is to take for granted the things
available today.
By the late 70s early 80s most OSCILLOSCOPES and
vast majority of instruments were ISOLATED by design.
Like it or not we lived and changed methods and the BRAIN
for that.. LINEAR PSUs (there were no SMPS "supervisors")
were norm and mostly FULLY ISOLATED.
My old archive still have dozens of scopes and instruments
with LINEAR ISOLATED only mains..
so.. unless you have lived with that .. taking these SMPS
and "differential probes" and fancy scopes of today and
thinking they are safe by default...
just will not fit the kind of hard methods old school forces you
Attached a typical OSCILLOSCOPE FROM 70s MAIN PSU.
FULLY ISOLATED by default CHASSIs NOT GROUNDED
that kind of care was left to the technician as much as
the methods to touch a 600V HOT tube with their instruments...
Not an easy time to start... lessons learned
BTW this was my first scope... w/a COLINE 100x probe
best and safe enough to go
Paul