I'm not sure and hope one of the wiser folks on the forum might offer some suggestions for what to say.
The symptoms that confronted me were basically "PSU does not go". The +5V standby was available, but you couldn't turn the system on.
The SG3524 regulator IC will be on the secondary side of the PSU, so in principle it's not the most dangerous place to be poking around with a 'scope, but when I was troubleshooting my DataPower PSU, I wasn't feeling that brave. I first checked discrete components with the PSU off and caps drained, and when I found nothing suspicious (diodes appeared to be diode-ing, etc.) I started pulling ICs and trying simple ones in a breadboard. All the comparators worked fine, at least in response to me twiddling the knobs on a bench PSU (so a very low-frequency signal of course). I didn't think for too long about how to test the SG3524, which seemed like it would be a lot more complicated; if I was going to take it out anyway, I might as well just replace it. So I did and everything was working again.