Chosen Solution
Hi guys, I have recently acquired a 2017 21.5” iMac which is dead. Only 1 of the diagnostic LEDs are on, so I changed the PSU and it’s still the same. I have disconnected all (but the PSU connections, tried an SMC reset, drained all the power and took the Logic Board out and gave it a visual inspection but now I’ve ran out of ideas. I assume it’s likely a board level repair but I was just wondering if any of you gurus on here have any ideas, or obvious solutions? Any help would be greatly appreciated. Thanks, Andy.
Sadly, it does sound like you have a logic board issue. Unless you have the skills & tools to test it and can locate the needed parts (or have access to someone who does), you really only have one choice that’s replacing the logic board. Here’s one source for the logic board: 21.5” iMac Logic Boards and here’s the guide: iMac Intel 21.5" Retina 4K Display (2017) Logic Board Replacement Update (08/14/2021) @andyc7117 - Sadly finding schematics and boardview’s for the newer systems is becoming much harder as Apple has transitioned from the older 820-xxxx board ID to a four letter code which includes the CPU & GPU and its VRAM layout. If you open the link I posted you’ll see the board ID’s J0DX, J0DY, J45F, J45G for the first listed. These are on the QR coded label which is applied when the board is populated. I have yet to spend the time to decipher this Apple gobbledygook!
