On 3/28/22 17:22, Rob Jarratt via cctalk wrote: That's probably not real.? It looks like noise pickup from the probe ground lead.? Try disconnecting the probe tip and see if you still get similar signals.? I have seen similar noise lots of times when measuring things with switching power supplies.? The high frequency content is pretty unlikely to be actually there on the power rails, with a bunch of decoupling caps all over the boards. Jon