Rev A iMac - 233MHz, 32MB RAM, 4GB HD (this is a stock machine - not my hacked iMac I have referred to in the past)
Symptoms: when plugged in after sitting for some time, the machine gives a good chime and the power light is green, then a loud click and it shuts off completely. The moniutor never turns on. The machine will not repower on, even if the CUDA is reset unless the machine sits unplugged for some time (a few hours) and the CUDA is reset prior to power on. On some occassions the machine powers up, with the yellow and green lit at the same time and just sits there (no monitor, no chime), just fan, spinning drives - no real life. Hitting the reset button at this point throws me back to the green light, chime and then off again.
I have not tried swapping the mobo with my other iMac yet, but have the option on hand to try. The hesitation is I do not want to infect/jinx my other iMac that I have finally got working again.
Any ideas on what the problem is? My first thought is the analogue board, but I am uncertain if it is this or not. I am hoping that this sounds painfully familiar to others.
TIA
--DDTM
Sounds like your typical "Green Light of Death" ™. This is probably the AB (could be the flyback transformer). Usually everything else is salvageable....
Sorry for the news...
CM
I do not have these things (specs, notes, beer,...) in front of me at the moment and cannot recall of hand, the primary funtions the AB provides are as follows:
* AC/DC control - provides a power source for the mobo and monitor
* provides an amplifier for the speakers - sourcing sound from the mobo
...and what else?
The analogue board does not provide any power to the motherboard.
...what does it do for the mobo?
My plans here are to recase the mobo and drive an different monitor.
You don't need anything from the analog board if the goal is to recase the motherboard. The speakers are teed-off from a small circuit board containing the headphone jacks in the front of the case (which you don't actually need if the line-out jack on the motherboard is enough.), and a VGA-compatible signal is available either directly on the motherboard header or via the board in the back of the "bucket". (With the 15 pin Mac-style connector on it.)
If you're into making an ATX power supply converter you don't need anything from the monitor section at all. Frankly, I'd recommend it as the power supply board built into the iMac is *huge* and potentially dangerous.
--Peace
Oh, you actually need that small headphone board inorder for the line out to work. Most odd!
cool. kinda thought as much, but never really cared to retain this in my head as my other iMac is still working in this respect. with this I can build something wonderful - someday.
Really? I could of sworn I've run my disembodied iMac bits with a headphone plugged into that jack but without that part of the wiring harness hooked up, but... I could be wrong.
Definatly sure
I had no sound with my atx conversion until I plugged in the board.
I mean the board with the LED, power switch and 2 headphone sockets.
Oh also, somewhere on the old applefritter boards, there is a long discussion about how those boards often went wrong - and all sound would die on the machine until they were replaced.
...I thought that the mobo jack worked independent of the headphones jack - this is a Rev A machine we are talking about here.
Eh, you're probably right. I forgot the power switch was on that board too, so it likely was plugged in at the time. (Although sometimes I would power the thing up with the power switch on an original iMac keyboard.)
My guess is that the machine is designed to mute the onboard jack if it detects a headphone plugged into the front panel. And the board not being present at all triggers the response, for God-knows-why reasons.
--Peace