Chosen Solution
Hi all and I am stuck as to what is causing my iMac to not work properly? It all started last week when I booted my iMac 27" 2017 5k which is hooked up to a LG UltraFine 27" external monitor and only the LG showed the desktop whilst the iMac was just blank (no backlight and no image), so I rebooted and then nothing came on and the iMac was in a constant boot loop chime. Tried keyboard commands but all where unresponsive whilst the machine was in boot chime loop. I next tried ram pulls but that made no difference and produced no beeps etc. I then took my iMac to a local IT repair shop that deals with Apple products and a week later they called me to say the PSU board is ok, SSD and HDD where all good and the machine was running to an external monitor but without the main LCD screen on iMac, if the screen was re-connected it went back to the boot chime loop with nothing on either screen? The IT shop said they had no other 2017 models to test parts with and that it was either my LCD the has failed and if that did not fix the issue then it is a bad logic board? I would like to know if possible what part is more likely to be causing the issue as I cannot afford to buy a logic board and LCD as that will cost me more than I paid for the machine setup 2nd hand for £900 Update (01/24/2023) @danj I fitted the new screen on today and nothing but the boot chime loop. Disconnect the screen and iMac boots to external monitor but fans are running at max revs. I took pictures of the sockets and cables as best I can, the back of the original screen looks to have some heat buildup at some point
Update (01/24/2023) @danj this is the iMac diagnostics which is saying SMC and Graphics? I have a logic board arriving tomorrow to test that part as the new screen is being sent back.
Update (01/25/2023)
@oldturkey03 thats the display cable end and damage whatsoever along the cable. As before the machine has never been opened until now so the cables have never been touched or moved
What does the onboard diagnostics tell you? Restart the system and press the D key to enter. Try without the external and if that fails try with the external connected. Reference Mac startup key combinations Let us know what you discover!
