Chosen Solution
I’ve had the display my 2017 iMac replaced at a shop and according to the receipt the correct part LM270QQ1 (SD)(C1) should have been installed. Unfortunately, it has several issues that make me question this: It seemed less bright at first and the display settings menu now showed the image of a generic display instead of the iMac – since the store assured me it’s the correct model and I couldn’t check, I accepted thatAfter about a year the display shows strong image retention, an issue that was common in the previous 2015 iMac So far I could gather the manufacture date using EDID information which is mid 2015 and confirms my suspicion. Also according to a thread on macrumors, the model found in ColorSync is 0000AE07 which matches the older model and not 0000AE13. I wasn’t able to find these numbers anywhere else, so I can’t verify if this makes sense. I’d like to test a new screen to see that it actually is the right model and also have something to show to the store where I had the current one installed: Is there anywhere else I can see if it it’s the right panel either by model number or an output of what the maximum brightness is?Can I connect and check the screen before replacing the old one with an external cable?
What I can tell you is the Apple P/N for your systems display is 661-07323 and the marking on the display should be LM270QQ1 (SD)(C1) The 2017 has a brighter NITS screen than the 2015 which is Apple P/N 661-03255 the display is marked LM270QQ1 (SD)(B1). It had its issues! Ghosting being a big one LCD panel with image persistence (ghosting) when left static for periods of time. Now you’re is a no win position here! To validate the part you need to check its markings on the back side of the assembly
But the act of getting to it offers the shop an out as you invalidated their warrantee! You also risk damaging the display just in the process of taking it off, if you don’t have the needed skills and tools, review this guide iMac 27" 2017 Display Replacement
