Help on dc/ac inverter repair

[john120]

Hello everybody,I have a problem with my inverter DC-AC 750VA 250V;by mistake its output has been connected on the generator ;when I took measurements for reparation I found out that 2 IGBT (output stage made up by 4 IGBT) has burn then,all those 4 IGBT but now when I connect the battery on the input the input stage which is made up by 6 MOSFET F3205 are not giving a good output which has to go on the second stage of IGBT after replacing the burnt ones.what can I do for that .
The device is from victron Energy,Can anyone know how to diagnose this type of inverter?and help me .

The first stage is made up by 6 MOSFET,the second is made up by 4 IGBT and also there more than one transformer in this device .

 

[nnaveli]

john 120.check the 1st stage -the osc stage, scope for square/sine wave output,i hope the schem.drawing will help.

 

[john120]

I already checked but I am mandatory obliged to make another oscillator because the first one has had a great problem.
can you help me to understand how to make a SPWM signal of high frequency 20KHz as example.

 

[pradeep.g.belchada]

in the first stage dc 12v will be converted to 315vdc check it around 100mfd/450vdc cap

 

[nnaveli]

google tl494 circuts,then u will atleast understand.