Fast and easy iMac Intel 27" EMC 2390 power supply replacement
I was watching a uTube video when the screen instantly went black, with no fan or hard drive noise. The iMac would not power on. By the symptoms of the failure, I guessed that the power supply had failed.
First of all, I ordered the replacement power supply online from iFixit.com on Monday afternoon and it was delivered by 9:30am on Wednesday morning--amazing. Although I couldn't find a guide to replace the Power Supply in a EMC 2390, the guide for the EMC 2309 worked just fine. I took my time and carefully followed the 10 page downloaded guide. It took about 3 hours including setting up a work bench in a warm place, collecting my tools, and a 1 hour lunch break. My original power supply did not show any visible signs of failure, but when I reassembled the iMac it worked perfectly with the replacement power supply. My guess at power supply failure was correct. Now that I have been through the process once, I could repeat it in 20 to 30 minutes--it's easy. The suction cups worked great to remove the glass over the LED screen. The glass is held on with magnets.
As a retired EE that is accustomed to working with very high reliability electronics (spacecraft), I would like to stress the use of anti-static wrist straps any time you work with electronics that have semiconductors. Electrostatic discharge can wipe out ICs and you may never know it until things don't work. Just clip the wrist strap to the aluminum chassis of the iMac.
Heavy-Duty Suction Cups (Pair)
Anti-Static Wrist Strap
iMac Intel 27" EMC 2309, 2374, 2390 or 2429 Power Supply