Electronics > Repair

How does this diode work?

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naujoks:
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?

langwadt:
It's just two diodes in one package

naujoks:
I see. So it makes sense then that the left hand side is in the 12v circuit and the (shorted) right hand side is in the 5v circuit.

langwadt:

--- Quote from: naujoks on October 02, 2024, 12:20:25 pm ---I see. So it makes sense then that the left hand side is in the 12v circuit and the (shorted) right hand side is in the 5v circuit.

--- End quote ---

the diodes are connected, 5V and 12V wouldn't be cconnected like that

naujoks:
Is there any obvious reason why without that part the 12v line should disappear as well?

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