So my dad calls me up with a computer problem. Now, 9 times out of 10 it's something fairly generic like "Hey, the computer seems slower, what should I do?" But this time it is, "What would cause the computer to just not come on anymore? No lights, no fans, no nothing?" I suggest that power supply is the likely culprit, although worst case I suppose something could have fried his motherboard. He goes out, buys a new powersupply, successfully gets it installed and connected which is actually pretty impressive if you've never done it, and still...nothing. So he drops it off at the house.
I try it, he's right, nothing. I highly doubt that he's coincidentally gotten a bad power supply from the store. Ok, first step - being a typical geek, I happen to have a random open computer lying around that I am not using. So I connect up his old power to that computer, and it works fine. Therefore it's almost certainly not the power supply.
Next step I unplug everything from the new power supply (the one that is in his computer), except the main motherboard connection. Maybe something is loose? Nope, no good. Still nothing.
Then I notice something that doesn't....feel right. And I mean that literally. His computer has got the typical setup - the power supply in the back has a regular switch, but then on the front plastic casing of the computer is a big circle button that you push to engage. I'm pushing it, and it feels like it's stuck or something. I'm not hearing any sort of click.
So I pop off the front casing of the computer, always tricky depending on the computer maker, you don't know whether it's a pop off or it's screwed down or what. And sure enough I see a red wire connected up to an LED (hard drive), a green wire connected up to an LED (main power), and a black wire connected up to a little switch, just kinda hanging there. I push it. Computer comes on.
I then see that the two little plastic legs that were holding this switch up against the main power button have weakened enough that it was no longer close enough to the button to engage. That's annoying. It's not like you can easily replace a part like that :-/. So I slapped a bunch of electrical tape on it and called it a day. :)