I recieved broken powerware 9130 1000VA UPS with strange buzzing sound. Problem was in aux power supply, IRF640 mosfet was blown. I replaced mosfet and ups start working but as i was putting it back in case i shorted capacitors and blow all 4 mosfets, 2 gate resistors, sg3525 and one of the totem pole drivers. I replaced FQA75N10 with IRFP1234, replace all four totem pole driver transistors with 2N3904/06 and SG3525.
put it back in case and connect mains and battery. as i press power button there was sparks and flame at the end resulting in spectacular firework as all 4 mosfets were blown to pieces. What went wrong ? i think that all 4 mosfets conduct in the same time thus shorting the battery.

 

Pictures?

 

I will upload some pictures tommorow when i remove inverter board from the case.

 

Damage All MOSFETs are blown, gate resistors are okay, as well as totem pole driver and SG3525 !! unbelievable !!! what went wrong here... Output IGBT, as well as input rectifier, PFC IGBT and control board are fine.. OH and fuse as well

 

Damage All MOSFETs are blown, gate resistors are okay, as well as totem pole driver and SG3525 !! unbelievable !!! what went wrong here... Output IGBT, as well as input rectifier, PFC IGBT and control board are fine.. OH and fuse as wellView attachment 135598

I had exactly the same breakedown and at first attemt the gate driver circuitery was also affected. I replaced all broken components only to have this nice firework repeated...but without breaking the gate driving circuits.
Coclusion though is the same...they appear to conduct in the same time or possibly with far to long on time. Difficult to fix without circuit drawing.

 

WoW! You really managed to let the magic smoke out there!
If you give it another go, add a series mains light globe to try to limit the fault current a bit. that may help to save more damage while you work out what the underlying fault is.
After a quick on line search, I could not find a schematic for it.

 

Well, I thought I would disconnect the mosfets from the board and try to look at the signals on the small gate driver PCB but it is a liitle bit
difficult to power up the main Circuit Bord separated from the chassis. I actually dont have complete understanding of the SG3225 IC so I have some study to do.

 

Hello
I will try to help you if you have these
for safety:
Atx power supply 200w or 250w
Inverter(smps)(12v to 220ac) 500w or 1000 or ........
We will have to change your inverter a little
Atx ps is a good power supply with overvoltage protection
We need inverter to take 220 or 300 vdc to check your ups
Our current style is absolutely safe for your mosfets

Aplicant.