I looked up the ps52k on google and it looks like it has both voltage and current meters on the front. When you say "no volts or any thing" I'm assuming this means the meters don't move. (If that's _not_ what you meant, then please elaborate.)
I had a Pyramid power supply a long time ago. It was a 20 amp model (different from yours), but I somehow managed to pop one of the diodes in the bridge rectifier. Luckily Radio Shack sold replacements at the time, it was an easy fix. I didn't have any trouble with it after that.
I figure the likely culprit in your case is either a blown rectifier or a bad voltage regulator IC. Still, with the blown rectifier I would expect the fuse on the input to blow as well.
The "short buzz or hum" you describe is not necessarily abnormal (unless it's very loud and is followed shortly by a fuse blowing). When the supply has been sitting un-powered for a long time, the filter capacitors will be discharged. Once you flip the power on, they will look like a very low resistance load on the secondary winding of the transformer until they charge up, which takes a split second. During that very brief period, the transformer is heavy load, which can cause the hum that you hear. This is called in-rush current. Some power supplies are designed with a time-delayed relay that keeps a resistor in series with the primary winding of the transformer for a few seconds after you first turn on the AC power in order to limit this in-rush current and avoid putting strain on the transformer. (I think this is more of an issue with high voltage power supplies, where the windings are made of thinner wire.)
Are you sure you didn't overlook something obvious? Did you attach a test load to one of them (like an old 12 volt radio you don't care about) and set the voltage control knob correctly? It seems strange to me that both power supplies would be dead.
-Bill
