My Canon Pixma MX700 printer died the other day as it was printing. It just went completely dead, as if the power cord was unplugged. Today I decided to troubleshoot it. First, I tried a different power outlet. That was not it. Then, I checked the power cord. No problem there. Then, I took out the power supply box and disconnected it from the printer, then I reconnected it and put it back in. No improvement. Then I opened up the power supply box and examined the circuit board in it.
I am not terribly familiar with hardware, so I could not tell if the smell was of burned electronic components or if it was just the regular smell of electronics that have been sitting inside a closed box for a few years. Nothing looked burned though, and all the electrolytic capacitors seemed intact. I located 3 fuses on the board, and I checked each one of them for continuity. They were all fine.
So, I decided to give up, and I started putting things back together. I placed the circuit board back in the power supply box, I closed the box, and then for some reason I did something backwards: first I connected the power chord to the power supply box, and then I connected the power supply box to the printer. As I was attaching the connector, I noticed that one of the pins was momentarily making a little spark. And then lo and behold, the printer came back to life! The printer had fixed itself!
And that, ladies and gentlemen, is why I hate hardware.
UPDATE 2012/07/13: nope, the resurrection was only temporary. The printer is dead. Dead as a doornail. And that, ladies and gentlemen, is why I hate hardware even more.