/diy/ - Do It Yourself

I made a post in the previous thread, and I solved the problem. It wasn't a big one (I was just being a little stupid) but I'll leave it here.

I had a board with a buck converter as a seocndary power supply, and it was working half a second before stopping and restarting in loop. The controller is a Viper013hs. I think it was broken. It wasn't.
Well, I am ocasionally repairing boards with failed power supplies, and they are always failed buck converter.
Everytime, I connect the power pins to a power supply up to 63V. It always work, it's a pretty low voltage, but I never had problems with it. I have powered TVs with that PS.
Well, this time, it wasn't working because of my power supply. The IC was restarting because the output wasn't achieving the needed voltage for the feedback pin, and it interpreted that low voltage as a shortcircuit or overcharge.
Connecting the board to mains power, it worked just fine.

Pic related is a long exposure photo (5s) of my scope displaying the output voltage (up) and the voltage on the IC feedback pin (down).