Model A1311 / Late 2009 / 3.06 or 3.33 GHz Core 2 Duo processor

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Fresh Install - Screen Goes Black and Never Returns

Hi Everyone! First post here. Been a tech for 20 years but not all that much experience with Macs.

Got an iMac EMC 2308 in the shop the other day with a bad hard drive. Put a new drive in and tried the install, it starts up and gets going but after a few minutes the screen goes black. Eventually the fans spin up like it's going crazy but still nothing on the screen. We let it run once overnight in the hopes that we were just impatient, but no such luck.

Incidentally, at least one of the pins on the LCD cable port on the logic board appears to be de-soldered, but the screen does come up for the beginning of this process - It's just got a yellowish haze toward the bottom of it.

Is this iMac just telling me, "Nah, man, you have to fix that LCD thing before we'll let you reload," or is it something else?

Answered! View the answer I have this problem too

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Apple used different hard drive heat sensor cables on this machine. If you changed brands of hard drives you will need the corresponding cable. Or you will get a run away fan. See the three different ones here:

On your video issue, what does it do on an external monitor?


LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

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They're both Seagate drives. Different models but they both run at 3gb/s (SATA II).

Unfortunately I haven't been able to test external yet because I don't have the silly Mini Displayport connector. It's on order but hasn't come in yet. (Unfortunately we're too far from any Apple retail locations.)


I had this issue with a Seagate SSHD. Went with the OWC in-line heat sensor which solved it:


Mayer, is this OWC sensor "universally compatible" or will I need to choose the correct one of the three that you mentioned first?


There are different ones for different year models from OWC. They are not always needed when using the same brand of drive, get it only if the fan is running away.


The fan is running away, for sure, but the screen also goes black -- same issue or different?

Are there different model years for A1311 EMC 2308?


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I am by no means an expert on iMacs but from experience this is most likely the GPU. It works fine until OS X loads the drivers at which point it fails. You can usually test this by booting the iMac into safe mode (Hold SHIFT on startup until you see the apple logo) The machine should boot fine. If it is the GPU you may need to reflow the GPU.

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