Power supply issue with H240AS-00.

[Mechanical]

Hello, everyone.
The power supply had the standard problem, a blowout in the snubber circuit. I recovered everything from it. Q51, IC301 is also rebuilt. The power supply works, but when I hook it up to work on my power supply tester https://www.amazon.com/Computer-PC-T.../dp/B076CLNPPK, the Q51 starts to gradually heat up and after about 30 minutes it's hard to keep your finger on its heatsink. The other radiators are ice cold and so should be no load in out. All voltages are available. Where can a problem be found?
Regards, Teodor.

[CapLeaker]

Re: Power supply issue with H240AS-00.

I guess you are new around here, so welcome to badcaps! If you do make a thread like this, you better attach some high resolution, straight shot pictures using the attachment function. Like right now I have no idea wtf Q51 is or does.
I’d suggest you load the PSU properly up. Your problem may solve by itself, since some ATX power supplies weren’t made for running idle with zero load on it.

[stj]

Re: Power supply issue with H240AS-00.

if q51 is the main fet then you probably missed something damaged in the gatedrive circuit and it's not switching fully on or off.

[Mechanical]

Re: Power supply issue with H240AS-00.

Hello.
I am attaching a photo of the main FET.
Despite the unhealthy appearance of the front capacitor, I measured it and it is healthy (I replaced it, the behavior of the circuit is the same).
Photo of the small board behind the main FET. It is before I changed the PWM chip. I don't have time to desolder and take pictures right now. I measured all the diodes and resistances in the signal path to the gate of the FET everything seems normal. This is what my pocket oscilloscope shows. The readings of the unit are while the power tester is attached.
There is a small button for turning on the power supply. When I run it only through it, the device does not pick up pulses, only disturbances.
Greetings to all