On Nov 30, 8:14*pm, "Arfa Daily" wrote:
"pfm" wrote in message

...

Thanks all for replies. Please google for 'Fundamentals of Floating
Measurements and Isolated Input Oscilloscopes'. This is a Tektronix
application note. The situation to which I refer is is at the bottom
of page 4. *I want to use an oscilloscope to check the PWM switching
chip on the primary side of an SMPS.

BobH

I do this all the time - virtually every working day in fact. My current
scope - a 4 channel 100MHz Hitachi that I've had from new - is probably 25
years old now, so if it has been suffering "cumulative damage", it's bloody
slow to reach a point where it's a problem ...

My scope is normally grounded to the incoming line power ground connection.