Chosen Solution
I have an external portable Freecom self powered USB drive which did not mount on my older MBP. It just clicked continuasly, its utility password partion would mount momenteraly and then turned its blue light off. The mounting problem is the least of today’s disasters… So I powered up my imac and connected the external drive to it to see if it mounts on the imac. Once the freecom was connected , the imac turned off immediately and it would not turn on again. Checked power, disconnected power cable, waited, tried again, tried SMC. No change. The iMac will not power up Would could it be and how can I identify what is wrong? How can a drive with mounting issue cause the iMac to die? Thank you
Ouch! The drive may have a short across the power and data lines. Let’s see if we can get your iMac working. Disconnect everything from it as well as the AC cord. Now press and hold the power button a good 30 secs. Now plug the AC cord back in and now press the power button again did you get any response from your system? Fan noise? Update (02/20/2020) Here’s the location of the diagnostic LED’s
Here’s a breakdown of the onboard diagnostic LED’s: 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.
