Diagnosing random elements (MOSFETS, diodes etc.) on random motherboards.

Hello.
Is there a big guide about how to diagnose random computer related components mostly MOSFET transistors/diodes etc.?
I would like to know and learn what can I diagnose using a simple voltmeter (eventually using also a battery rated 9 volts which currently I don't have ) so I can repair motherboards, videocards, power supply (notebook and PC), LCD monitors (inverter motherboard).

If there isn't such guide can somebody guide me . I read some articles but what is said there doesn't seem to happen in reallity like charging the MOSFET between Gate and Source and after that measuring the Drain and Source. Maybe it was N junction and not P who knows ;D.

Can I diagnose/test MOSFET while it is soldered?
Also if I measure a short circuit between + and - on a soldered capacitor and the diodes/rectifiers are okay which is most likely causing the short circuit - MOSFET?

It's virtually impossible to recommend how to proceed. You can make a general component tester, but this won't help the fact that the components on a board are part of a circuit so you're interacting with the entire circuit not just the component, outside of removing each part from the board there's no way to determine what else might be interacting with it without having a detailed schematic which you won't find for the types of boards you're talking about.