My Wanptek 605W blows bridge rectifier and two diodes around the mosfets, but why?!?!

I'm talking about an annoying problem with my old variable power supply. I still have no idea what's wrong with it!

The bridge rectifier blows and also two diodes near the mosfets. Many other components appear to be unharmed.

It's a High-Side problem. I've replaced the diodes and bridge rectifier and it blows again!

What's going on!?!

[Shmbler]

Looks like a simple half bridge SMPS like the old ATX ones. AFAIK the NTC is there for limiting the inrush current into the two big caps. Those NTCs get quite hot and I've seen a lot of them die just of age and heat. But if you just short it instead of replacing it, the inrush current may kill everything in it's path, including the diode bridge. That would be my guess.