Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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Replaced PSU, beeping once, no video

So I previously posted about my iMac not booting up, thanks to some help I replaced the power supply and I have power and 3 LEDs. But now I'm trying to turn the thing on and get the fan noise and all that but the screen stays black and it continues to beep once every 4 seconds or so. I read that it's possibly a RAM issue, any suggestions or recommendations?


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The 4th LED indicates that the LCD panel is connected and communicating. The Mac "should" boot with it disconnected but just for the sake of trying maybe disconnect/reconnect the LCD panel and attempt to power on again? The single beep is also a RAM error, you might try isolating the RAM by installing one DIMM at a time and trying to boot.


Well I'm guessing its the monitor if the last LED isn't on. I think I reconnected everything properly though..when I unplug the LCD temp thing the fan kicks on a lot faster, it might not be anything but I feel like something simple is wrong and idk what it is. Also don't know what a DIMM is. It boots up fine just no 4th LED and no display and it beeps once every few seconds..


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DIMM = Dual Inline Memory Module (aka RAM card or chip)

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You think it's a RAM issue even though the 4th LED light isn't on? I have everything reconnected the right way and still getting black screen and beeping.


No I don't think that I answered your comment about "don't know what a DIMM is" - (LikeARabbit said he had a machine with bad RAM exhibit your behavior) Have you connected an external monitor to the system? That may work. If it doesn't it points to a VGU/VGC problem.


I got the beeping to cease with new RAM, still no monitor or 4th LED. Don't know how I would go about connecting an external monitor (what do I need for that? At this point it could be the cables or the whole screen could be out, ya?


Your internal cable, inverter or the actual LCD could be the culprit.. listed in order of least->most cost & work to check/replace... Yes you need a mini-DVI to your monitor type connector/adaptor to check that the VGU/VGC is working.


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