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Computer Power Supply

1) Bridge rectifier and filter caps
2) Transistor
3) Transistor
4) Transistor
5) Stand By Controller
6) Main Power Transformer
7) Signal Transformer
8) Stand By Power Transformer
9) Optocoupler
10) Schottky Dual Diode
11) Schottky Dual Diode
12) Schottky Dual Diode
13) Schottky Diode
14) Schottky Diode
15) Output filter Common mode chokes
Capacitors and Chokes
16) Main Controller
17) There is a capacitor on this rail that commonly fails.
When this happenes PSU refuses to turn ON
18) There is a resistor and capacitor on this rail.
They are next to each other and resistor heats up the capacutor.
When cap dies because of heat, the whole Stand By subsystem blows.

Optocoupler example EL817

Transistor example MJE13007

Diodes example

Controller example TL494

Short two marked pins to turn power ON
Left of these two is the PS_ON pin.