I'm trying to repair an early 90s PC PSU, which has no +5V.
There is a dead short on the 5V rail.
I found out that when I take the diode S30SC4M out of the circuit the short disappears.
I can measure a short between pin 2 and 3, but not between pin 1 and 2, so my assumption is that this diode is faulty.
I'm not familiar with this kind of diode and I'm interested in how it works. It seems to have two diodes wired against each other, so does that in effect make it a transistor, or a MOSFET?
Interestingly, when taken out, the PSU also doesn't have 12V output. Is that the expected kind of behaviour how it works, that it's responsible for the 5V and 12V output, and maybe the other voltages too?