After hitting the power button, I hear the startup 'chime' then wait about 5 seconds and bang..the hard drive clicks and the system powers down...i dont think its an issue with the HDD it just sounds as tho its parking (so im assuming to prevent damage the machine shuts itself down???)
Although at this point if i hold down the power button i hear what sounds like the machine is truly shutting down...
Well anyways..ive taken the bottom cover off, taken out the battery, gonna let it sit over night and then see if that helps. I have read about a PAV?? board...where do I find that Id like to disconnect that as per instruction @: http://www.capecodgraphics.com/imac_firmware.htm
This was a refurb unit and came with 10.2 and 9 pre-installed so Im 99.999% sure its not a firmware issue (apple wouldn't let a machine out with the improper firmware code would they??)
Im open to suggestions and ideas...
Did you try resetting the PMU? Zapping the PRAM? Reseating the memory? If none of those work, it's likely that your iMac's analogue board is broken.
... one of two things. First, try replacing your PRAM battery. iMacs tend to behave strangely when that battery is dead, and I remember someone else just recently talking about similar symptoms being fixed with a new battery. Otherwise, it may be a toasted power supply. I've seen that happen a couple of times in person recently, and did the same thing; The machine would give the startup chime, spend a little time trying to boot, then blah; dead.
The good news is that if it is a dead PS, you've then got case-mod material to work with; just get one of the marathoncomputer.com/imaconatx.html
well ive taken out the battery and ram...the battery has been tested w/ my multimeter and is putting out a very healthy 3.7...i did also take out the memory..the mac has now sit overnight..im gonna replace everything put it back together see if i can get in..if not ill let ya know
here's an update...
here's what i get after i put the imac back together...
pretty much same thing, but since i had the cover off i was able to see some strange activity at the power button...
since the led was explosed it was alot easier to see the subtle amount of light coming off it...
id hit the power button to turn it in,
it'd come on, id hear the startup chime...
it would start to initialize the monitor...(i see the grey/white os x loading screen w/ the mac logo in the center...for a split second) and poof it shuts down..but the power button led would stay barely lit and sorta stutter a bit...if i hold it down, it shuts off completely...if i hit the button again, it'll power up, just to power down (or now, it seems like a sleep mode...)
i hope this isn't confusing to everyone out there, but im thinking its either the main power supply unit or the main board..
iMacs also had some issues with sticky power buttons, and that would manifest itself as some pretty bizarre behavior. Think of what would happen if you were constantly pushing on the power button; what would your Mac do? The default setting (I think) is for the machine to sleep when the power button is pressed, which may partly explain why your iMac is going into sleep mode while starting up.
Google for iMac power button fixes; basically what is recommended is to carefully shave the opening for the power button to allow it to move more freely.
Keep us posted.
well durin that time where i told you i was having that weird sleep/led stutter issue i didn't have the bottom cover on the unit..so that outside button wasn't attached...the button does move freely without catching...that was definately one of the first things I have checked...hmm ill keep on try tho..thx guys..
I bought an imac for my son on ebay and found this while trying to troubleshoot my iMac problem. I've got a 500mhz. My machine does the same thing. Once in a while, I can get it to boot when it's upright. usually after it's sat for a day or two. Then the drive parks and it shuts off with the power light glowing dimly after about 5 min. I replaced my battery too and did the usual pram zap and cuda switch reset. The funny thing is that my imac starts up and runs perfectly when it's upside down. As soon as I turn it right side up, it shuts off. I don't have a boot CD right now for OS9 (It only has 64mb of ram right now), so I'll try that next. I had a CD that I thought would boot it and it seemed to behave normally when I held down the C key while starting up, I just got a flashing ?. Most of the time if I try to start up, the power light on the startup button glowes dim, it never does the bright initial flash (unless it's upside down. I think I'm going to try replacing the HD. It's got a drive swapped from I don't know where. Ahhh ebay... Any other ideas? Did you solve your issue?
I've had your experience with a couple of iMacs, and then I read on the web how it's a common problem with the PAV's mostly because of persistent heat issues with the iMacs. I think there was even a class action suit raised at one time against Apple about it. My friend took hers to the Mac dealer and they confirmed it was the PAV and then replaced it for her for almost $300. It practically spun my head around when she told me since the machine wasn't worth that much, but you know, she didn't want to have to think about it and have to deal with getting a new computer and just paid it. PAV's sell on eBay for around $150-$200, but they're very difficult to replace, and on top of that, the procedure is fairly dangerous. You'd be messing around close to capacitors which can be deadly. My advice: once you're iMac starts doing what yours is doing, salvage the parts and chuck it.
Yeah, thanks. I appreciate the feedback. After spending way too much time messing around with something that cost me $100, I'm going to put it in my pile of dead mac stuff in my basement. iMac parts anyone? Ahh defeat. Oh well. Back to ebay...
I've seen this behavior before - was the result of an iMac that had OS X installed, but the necessary firmware updates hadn't been done. I know it can be fixed, there are fixes out there on the web. I recall macintouch having a thing on it. If you call Apple, and explain that os x was installed and this is happening, you can get a CS code, and the machine repaired free of charge.
does it have a dvd-rom drive or any form of dvd reader? i'd be interested in buying the dvd-rom drive if it has it.
Uh, what is in your pile? I may be interested in buying some nostolgic junk :).
My imac had the same problems. Yes it is the PAV board, but more specifically the flyback transformer on the pav board. Instructions on how to replace the flyback can be found here http://www.macopz.com/columns/imacrepair/. Please note that this is very dangerous as the the voltage around the PAV board and CRT are very dangerous (exceeding 1000 volts). The CRT can also be accidentally shattered. You must know how to discharge a CRT. This repair is very dangerous and complicated and requires soldering knowledge. Buying a Flyback is a lot cheaper. about $30. you can also get dead PAVs for under $30 sometimes on ebay (just needs a new Flyback). Another option is to convert an imac to work with an atx power supply and use an external monitor. Note that this is also very complicated, requires soldering skills, and deals with high voltage components. Search google for "imac to atx" for guides. I can also help as I have transfered my imac DV 450mhz to a pc case and am using atx power and an external monitor (questions? e-mail me at Kyogre56@gmail.com. Please note that these repairs/conversions are not for the faint of heart. Some electrical components can kill you if you arent careful. I am in no way liable for personal damages. You have been warned. I only did this because I would hate to part with my dear imac and that I don't have money for a new mac right now.
Whatever you may decide to do, good luck.