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

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iMac 21.5 late 2009 blackscreen, gpu to replace?

hi folks

so I got this iMac EMC 2308 which can start but with a black screen. Diagnosis LEDs show me 2 LEDs lighted up, the 2 first I guess. I see them through the bottom of the iMac, at the right side of the RAM.

The screen doesn’t show anything even with a flashlight. Nothing happens when I plug an external screen. Bluetooth mouse and keyboard don’t connect to the iMac. Well I guess the GPU is dead, right?

Is there anything I can do/test to be sure of this pronostic? What do you think?

Thank you

B.ox

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crwdns2933897:0crwdne2933897:0

Sadly, I think your logic board has died. This series uses two chips (North & South Bridge) for the South Bridge chip is responsible for the I/O to the SATA drives, USB, PCIe devices (WiFi) and Audio. This chip has failed.

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Does it change your feeling about it if I add that the iMac plays the starting sound on start up?

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

Sorry, I've seen this failure before and spent days tearing out my hair. I'm sure!

You are expecting the whole chip would fail, so f the audio is working how could the chips be bad? Here it's the other parts of the I/O circuitry that failed.

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

thanks dude. So need another logic board... ok.. I would never have guessed an issue of this kind by myself!!

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

hi there... so i bought a 2nd hand logic board and replaced the former one.. and the result is staying the same... so i hope you guys have a clue of what's going on because i really don't :o

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

Sounds like you got a bad logic board, return it and get your money back.

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