Folks,
I'm ealing with a switching power supply and when I connect the scope probe ground to the board ground, the scope get noisy even before I touch the probe tip to the signal I'm trying to measure. It not my first time running into the problem and I'd like suggestions on scope hookups that would not be as suseptable to this noise.
I've trised taking the ground wire off the probe and using a short piece of buswire wrapped around the ground probe near the tip. It helps some but I still get noise when I touch probe ground to PSU ground.
I've also tried floating the scope with little success.
Is a differential probe the only way around this?
All of the text books say itscommon mode noise and to use a common mode noise filter to prevent this noise from radiating in the wires to the unit. but that essentially traps the noise in the part I want to measure.
Any tips?