My bluegate ups was working before the battery spoilt. After I changed the battery, Then I noticed that 2 of the mosfets in the circuit were defective. So I changed them. After a while, the mosfets I changed burned out and FIRE started coming out from the ups. I quickly turned it off and then , all 4 MOSFETS in the ups DIED. The mosfet is FP50N06. My worry is that the mosfet just burnt out without even showing a sign. The ups model is 1200VA. My queston is: Is it that the replacement was a fake? And if it was, how do I identify FAKES?

 

It can be very hard to spot fakes, even the manufacturers have troubles telling if a component is their own or an imitation. You can buy from one of the big resellers like farnel, mouser, RS etc. and they are then 99% likely to be genuine. However, you mention that you "that 2 of the mosfets in the circuit were defective"... this actually suggests that there might be something else that actually caued the problem in the first place, and it might not actually be the FETs that were to blame.

 

When I mean burn, I MEAN IT NEARLY CAUGHT MY HOUSE ON FIRE! But the strange thing is that the ups still turns on...

 

But what I noticed is that the mosfet sizes had a very slight size difference and name...