12-220V inverter fault diagnostics

[pc.alpujarra]

Hi, I have here 12-220V inverter which starts normally but turn itself off after 3 sec and red diode on BOARD turns ON. The 5V usb output from inverter works fine.
What I tried:
- I followed input power lines up to the board OK
- Fuses are OK
- Checked voltage on biggest capacitor when device on, It went up to 300-350 V (33uF,400V) but drops when red diode starts.

Where to continue?
How to check the big transformator?
Thank you

 

[alec_t]

More techno information needed. What make/model? Can you link to the inverter datasheet?

 

[pc.alpujarra]

TD DIS 300W power inverter (some french stuff) difficult to find anything useful about it
homepage http://tddis.com/ whis is like label on it but maybe just rebranded chinese noname
can upload pictures of internals if needed

 

[2PAC Mafia]

You should find the main PWM IC circuit on board looking for datasheet and test power transistors. If it is an inverter I don´t know what you mean with big capacitor. Usually the conversion is from 12V to 220V so no 300V needed as when a dropdown SMPS.