iMac (mid 2006) screen goes black

[M87]

Let me start by saying I have swapped the ram in the computer and the problem persists. I've also tried resetting the PRAM. I have unplugged all devices except the keyboard and mouse. I have reformatted and installed OS X Leopard, Tiger and Snow Leopard. I have even encountered this issue while the computer was running from the install disk. I'm pretty sure software, ram and third party devices can be eliminated from the possible causes. The computer continues to run after the screen goes black. I am connected to it right now using screen sharing, so I know the computer is still working. Putting the computer to sleep and then waking it up temporarily brings the screen back until its next random blackout. I have opened the computer to replace a dead HD, so I suppose it is possible that I knocked something in the process, but I did that back in december and the problem is a relatively recent development. I would really prefer to fix this myself, if I could only figure out what the problem is.

Any ideas?

 

[geoffreak]

Try taking it apart again and checking all the connections. You might have disconnected a cable that connects the internal display.

 

[M87]

I just had a poke around and as far as I can tell everything seems to be connected. I installed Fan Control and it seems to be helping. Though, my mac is now loud as hell with all these fans running.

 

[M87]

Well, at least it seems like we've got the problem figured out (I hope). So far we have not experienced the black screen since cranking up the fans, but it's obviously not ideal to have the fans going full blast 24/7. There must be a better way to keep the computer nice and cool. I'm wondering if maybe the HD I installed is generating more heat than the factory installed one and that's what lead to this problem. What a headache! I just ordered a new mouse and keyboard for it too.

 

[Cymothoe]

mine too

I've been having the exact same problem with my mother's late 2006 iMac. When I took it in to the store at the beginning of the summer I was told the LCD was completely dead and that it would be better for us to buy a new machine than pay the $700+ to have the screen replaced.

A few days ago, however, the mini-DVI cable I'd hooked up to an external monitor came loose, and in the process of plugging it back in I must have jostled the motherboard, and the iMac's LCD came back on, looking good as new. Since then it's been on and off.

I took it to the store again today and demanded that they open the machine and check the connection between the LCD and the motherboard, but was told that just checking would cost $85, and it almost certainly was a graphics card failure.

Is it possible that the graphics card would be busted but still be able to reliably output a signal to an external monitor? It sounds like from your experience it wasn't a loose connection, but would it be worth my cracking the machine open to check?

 

[darrellishere]

Everyone seems to have forgotten the massive amount of graphics card failures on these 2006 models. I'm sure intel or apple are to fault but plead no responsibility for the massive amount of failures. Its a scandal and still boils my bones to this day! (3 mac purchases latter!)

I hope yours is just a loose connection and not a motherboard replacement.

Try smc fan control, just incase it is the motherboard/graphics card. For some reason with the fans set to max, it half brings my imac back to life. (Don't ask me why!)

 

[M87]

Everyone seems to have forgotten the massive amount of graphics card failures on these 2006 models. I'm sure intel or apple are to fault but plead no responsibility for the massive amount of failures. Its a scandal and still boils my bones to this day! (3 mac purchases latter!)

I hope yours is just a loose connection and not a motherboard replacement.

Try smc fan control, just incase it is the motherboard/graphics card. For some reason with the fans set to max, it half brings my imac back to life. (Don't ask me why!)

I have been using SMC Fan Control. I experimented with it until I found how high I needed the fans to keep it running. They're all at about half now and I've not had one problem since. I also shut down the computer whenever it's not in use to let it rest. It's not a perfect solution by any means, but it's something. The computer is only being used for simple stuff like web browsing, I'm not sure if it would tolerate anything more taxing than that.