Hello,

I recently start to have problems with S750 PSU. I repair it over the years 3 times and now it's 4th time. My issue is that after an amount of time the PSU shut down and came back to idle after about 15 min. I suspect the issue is related the fact that the TOP243Y was entering in thermal shutdown and came back only after it cools itself. I changed couple of suspect components and measured all capacitors and all seams to be fine.
However I have one question that someone around here might be able to answer. The PSU is running fine now but the L aluminum heat sink is very, very hot. I measure it with my fluke multimeter and it stay at about 70 degrees which is very hot. This is only when the main power (70V/24V) is on.
So the big question is if this kind of temperature is normal or not. In my experience is a little too high especially if the case is closed and heat is not dissipated actively. At least maybe to confirm my readings of temperature.

Regards,
Cristian