To find the on board diagnostic LED’s after removing the display look down into the cavity near the RAM slot assembly on the right you will find the LED’s often covered with a small piece of black tape. Once you’ve removed the tape, plug the system in do any of the LED’s light? If they do you should see if you can get the last two LED’s to lite but you’ll need to reconnect the display and being every careful not to tug on the cables as you can damage the logic board you should have a tight line to see the LED’s using some books or a block of wood holding the display the correct elevation.
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To find the on board diagnostic LED’s after removing the display bezel [https://www.ifixit.com/Guide/iMac+Intel+20-Inch+EMC+2133+and+2210+Front+Bezel+Replacement/992]
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Look into the cavity near the RAM slot assembly on the right you will find the 4 LED’s often covered with a small piece of black tape. Once you’ve removed the tape, plug the system in do any of the LED’s light?
To find the on board diagnostic LED’s after removing the display look down into the cavity near the RAM slot assembly on the right you will find the LED’s often covered with a small piece of black tape. Once you’ve removed the tape, plug the system in do any of the LED’s light? If they do you should see if you can get the last two LED’s to lite but you’ll need to reconnect the display and being every careful not to tug on the cables as you can damage the logic board you should have a tight line to see the LED’s using some books or a block of wood holding the display the correct elevation.