Hello, I recently got a bunch of AcBel API2P013 200W computer power supplies for free to screw around with and I want to modify one to be adjustable (mostly for fun and to learn something). I followed the board and draw a very crude schematic for one of them. first thing that got me is that the driver IC is UC3842B which would suggest that it’s a flyback supply (since the IC has no duty cycle limit) but that’s unusual for PC PSU + the rest of the circuit is clearly a forward supply design. The driving circuit is quite complex so I guess they somehow limit the duty cycle outside the IC? Does that even make any sense? Also I don’t quite understand the connection between 5V rectifier output and 12V winding (is that some funky way to create the 12V line ground?). If anyone could explain what’s going on with this design I would greatly appreciate it.