Thanks ronv for reply.
I checked today voltages on this PSU.
As always, you knowed it, yes, its faulty psu, there was 111V ripple on output(readed by multimeter set to AC).
Now I know that I also should check output with AC mode on MM...
<triple facepalm>
But I was thinking about new DL(uc controlled, 3' tft display etc), and I also found that vishay supply samples for everyone(max two orders for fake brands xd) so I can get mosfets for free.
Anyway Im not happy about it....
And of course your design was running all last time w/o any problems!
Also by making this DL, I learned something about cooling, and now im able to put 200W(mosfet case about 60C) per mosfet with standard cooling(heatsink+fan from 10yrs old PC CPU).
The key is soldering mosfet to piece of copper(35x35x4mm, salvaged from CPU thermal contact), and this module connected with heatsink by PC thermal grease.
By this way and 10 mosfets I can get even 2,5kW w/o water cooling
If you cant imagine what I mean, I can make photo of prototype silngle-mosfet, breadboard prototype.
In my dead DL I had soldered mosfets to copper pipe with 1mm wall which is too small, even with flowing 20C water inside pipe :|
So when I was reaching eg. 70C on mosfet case, there was 20C on other side of pipe...