Chosen Solution
Hi everyone, I repaired the iMac GPU card by doing a reflow in the oven (typical procedure for fixing that batch of GPUs): Mid 2011 27” iMac, AMD Radeon HD 6970M 1GB GPU. Reassembled everything and the problem seemed to be solved. Suddenly, after about a week of proper operation, the computer shut down and now there is no sign of life (pressing longer the power button , I changed the power cable, changed the wall socket, tried to remove RAM. Nothing) I mention this detail: I did not do the reflow myself and the person who did removed the GPU from the oven too quickly at which time two diodes were unsoldered. Then I re-soldered by reflowing again with solder paste. What could have happened? Could it be just the GPU shorting and not starting the iMac or something else? Anyone have any ideas? Thanks in advance
What does the onboard diagnostic LED’s telling you?
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.
