So I have a simple 2 stage SMPS, boost then buck, using ST's L6563 and L6599. I want to measure the gate drive and other signal components on the ICs. However, whenever I connect the Oscilloscope ground alligator clip to the common ground, my fuse blows. I'm not sure what the problem is, the simplest explanation would of course be that its causing a large inrush current, but I'd like to know how that makes sense, if that is the case. I tested with the oscilloscope powered off and just connecting the pins as well, but same result.
Without the oscilloscope clip, the fuse doesn't blow, but I'm not able to troubleshoot the reason why the 6599 is driving wrongly. Using a multimeter, I can get some voltage values but that isn't entirely helpful. Thank you.