What the hell could cause a power supply to shudder? I imagine that means it vibrated in a fierce manner. ![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
Current surge, like due to a huge short (and having nails instead of fuses). You sometimes see this during power-up in PSUs with huge filter caps, if the design lacks inrush current protection. See large class A audio amps with passive PSUs.
![Cheesy :D](https://www.eevblog.com/forum/Smileys/default/xcheesy.gif.pagespeed.ic.KPzuH4J-TG.png)