My wife's Rev A iMac started experiencing the classic symptoms of power supply board or analog video board failure a few months ago, but we didn't want to shell out the $$$ to get it repaired, so it's been collecting dust in the corner for a while.
Inspired by the Marathon iRack and iMac Rack-Mount Project, I recently decided to disect the iMac's dusty cadaver and attempt to reassemble the parts into some sort of headless Frankenstein computer. As you can probably tell from the subject though, I have failed thus far in my efforts.
Here's what I have done and what symptoms I'm experiencing now:
1) Took everything apart.
2) Connected logic board, HD, CD-Rom, A/V board, speakers, and power button back together.
3) Wired a harness to convert a 20-pin ATX power supply plug to fit the 24-pin plug on the iMac's power filter (I think that's what it's called -- it's the board that sits under the logic board and looks like it has a transformer on it...it takes 24 pins in and puts 26 pins out).
4) Rubbed the paddles, yelled "CLEAR!", and turned on the power supply.
Nothing happened. Well, that's not entirely true. The power supply fan kicks on and a tiny LED blinks on the logic board. I think it was labled "DS1" or "DF1" or something like that (I don't have it in front of me right now). It was in the back right corner, right next to the CUDA Reset button.
There is no boot chime and the HD does not spin up.
I tried booting with and without the keyboard and/or monitor attached. Still nothing.
I tried pressing (for 1, 15, and 120 seconds) the CUDA Reset button. Still nothing (although one time I tried pushing it down with the power turned on and the power supply's fan sped up considerably and the LED blinked faster).
I tried removing and replacing the lithium battery. I did not try replacing it with a brand new one, but there was still enough juice in this one to run a fan (I don't have a voltmeter).
So that's where I stand now...lots of iMac parts, but no shockable rhythm. Does anyone have any ideas as to what the blinking LED means or any suggestions on where to go from here? It was running like a champ before developing the initial power problems.