scope probe problems

[jamesrnz]

hi all,

i have been trying to chase down some ringing.

accidentally if out that grounding my probe to it clip and touching ground i get ringing. at about 2 mhz...

any suggestions on how to fix this?

also what is the best way to isolate the ground to measure my high side stuff

[Serge66]

Hi,
Use a separation/isolation transformer to power up the amp or whatever you are fault-finding.
Be careful!

You can also use the separation/isolation transformer to power up the oscilloscope. BUT then if you connect the probe ground to a hot point/high voltage, your oscilloscope chassis becomes LIVE.
Again, be careful!

I thought I had ringing in a switch mode PSU transformer until I connected both probe grounds to the exact same spot.