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Persistent horizontal lines appear on iMac screen

I am reaching out to share an ongoing issue I, along with several other users, have been experiencing with our iMac 24-inch models, and to seek a collective resolution.


Problem Description:

  • Persistent horizontal lines appear on the screen, which significantly hampers the usability and visual appeal of the device.
  • This problem arises without any physical damage, and despite the stationary nature of the device.


Steps Taken:

  • Connected to an external display: The external display works fine, indicating the issue is with the iMac's internal display.
  • Reinstalled the OS: The problem persisted post reinstallation.
  • Avoided operating the iMac for a week: No change in the situation.


Concerns:

  • The cost of screen replacement is high, and there's no assurance that it will resolve the issue permanently.
  • The quality concern is alarming especially for a brand that positions itself as a premium segment player.
  • The support received thus far has been unsatisfactory, with no definitive solutions provided apart from a costly screen replacement suggestion.





Please do not ask us to visit to service center and replace the screen for 650USD + , problem happens mostly after warranty.


[Edited by Moderator]

iMac (M1, 2021)

Posted on Oct 21, 2023 10:40 AM

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Question marked as Top-ranking reply

Posted on May 19, 2024 8:45 PM

According to the Apple support team I contacted, it's an LCD malfunction and the only solution is to replace it.


What they didn't say was why this problem is occurring after two years of using the iMac on so many computers.


So, as Apple hasn't yet assumed that it's their fault, what I did, given the lack of concrete answers from Apple, was to take my iMac to a technician and ask him to assess the problem to see if it's a construction problem or just a random fault.


The explanation I was given was as follows:


In terms of circuitry, everything seems to be working properly.


The problem, apparently, lies in a cable that also powers the LCD, which is located on one of the tops of the screen, and which, in order to be replaced, requires detaching the screen glass from the LCD itself, which is a very sensitive operation and almost impossible to carry out without damaging the LCD.


So the only option is to replace the entire LCD (LCD+main boards+screen glass).


Also, according to the technician's explanation, this cable (of the FFC/FPC type or Flat Flexible Cable / Flexible Printed Circuit), it has to sustain a very high voltage (around 50V) to power the LCD (this despite the iMac's power supply being 15.9V), and it heats up a lot!


So, what happens after a while (in this case after about 2 years) is that it starts to burn out and degrade at the connector, to the point where it lets the signals leak between the various connectors and short-circuits some of them, which ends up causing those lines that we are all unfortunately familiar with.


The level of brightness makes a fundamental contribution to this problem. Thus, the higher the brightness used, the sooner the problem occurs.


This is easily understood by measuring the difference in temperature at the top of the screen when it is at its lowest brightness level, compared to when it is at its highest. It's quite a big difference!


When it's at its lowest brightness, it's practically room temperature; when it's at its highest, you can almost "fry an egg"!


I think that as soon as Apple recognizes that there is a problem with these computers, the first thing it will do is make a change to the OS that reduces the maximum brightness limit allowed (to less than 500 nits). Time will tell...


Why does this happen?

For at least one of three reasons:

1- a design flaw - so this problem is likely to occur in a large number of devices;

2- a defect in components - the problem is limited to a few cases;

3- use of components below Apple's standards - the problem may be limited, or more widespread.


This was the explanation I was given. I'm not a technician. Only Apple will know the exact reason(s).


If I had to guess, I'd say that I don't believe it's a design fault, because Apple has an obligation to be very careful about that; I also don't think it's a fault with the component(s) because it seems to be happening all over the planet and doesn't seem to be localized; so I think it's due to the use of component(s) below, or at the limit of, Apple's standards which, when put under extreme stress (higher brightness), end up failing.


I think it's already clear to everyone that this is a design or manufacturing defect in this Apple model.


So let's hope that Apple takes on this construction problem and repairs it or at least contributes part of the cost of the (overly expensive) repair of our computers.


If it were a car, surely all our computers would be called into the workshop to replace the component that has broken down or is in the process of breaking down.


As it's a computer... let's hope that Apple will behave in a way that suits its customers, who believe in the above-average Apple standard...


So keep presenting your cases to Apple.

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Feb 26, 2024 4:17 AM in response to latVm

Same problem for my 2 year old iMac. The horizontal lines appeared shortly after 1 year. I brought to Apple Store and got quoted SGD$950 to repair the screen. The cost is more than half the price of the iMac itself. Hopefully Apple acknowledge this issue and offer repair programmes.


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May 13, 2024 7:15 PM in response to latVm

Mine had this problem too first like this:


i'm using it only for browsing and watch youtube, it not dissappear after I upgrade to sonoma, If I touch on the corner left upper on my display screen it overheat like it will burn my finger:



I bought this iMac on Yogyakarta Indonesia on November 2021 and after 2 yers 5 month use, my iMac turn like this. So I decide to bring to AASP (Authorized Apple Service Provider) because on Indonesia doesn't have yet an Apple Store Official. The diagnosed that LCD failure so I have to replace it for around 800$ or 13Million Rupiah. I canceled the offer and bring back my iMac after a week for diagnosed. When I turn it ON again, the flickering were dissappear but the new line appear like this:



it happen globally not only on one or two area, it LCD defect or manufacture failure because many people have same symptoms.

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May 20, 2024 8:33 AM in response to Newcompguy12

I have the same issue on my 2021 M1 24" iMac since 2023.11. My screen occasionally flickers and there's a black line fixed appearing at the top. The support told me it would cost 20,000 TWD to replace it. They suggested either using an external monitor or purchasing the latest M3 model would be more cost-effective.


I found the issues all are from after using 2 years.

Since there have been numerous reports of the same issue, shouldn't they initiate a recall to inspect the product problem? 20,000 TWD is already half the price of buying a new one.


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May 20, 2024 2:29 PM in response to latVm

I have the same problem after 3 years of use. My iMac has been used carefully and everything works normally except for those black horizontal lines at the bottom. Apple, please!!!, help with this. We have relied on the quality of your electronic products when making these costly investments and I understand that it is not fair that you leave us stranded in this way.

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Jun 20, 2024 3:35 PM in response to latVm

An update:


From what I can observe, the lines do not only flicker. Right at the top, where the lines begin, there are reflections of what's on the display below. I am attaching a few screenshots that experts can observe. Also, if hardware experts are monitoring this discussion, do hardware problems look like these? Something on your screen finding reflection on a different part of it?







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Oct 28, 2024 11:12 AM in response to latVm

Hello, I Had Been Using This IMac Since 2021, But There is A Screen Issue Which Was Arises Last Year. This problem Occurred without any physical damage, There Been A permanent Black lines Which was very annoying, Me and Many User Facing This Same Problem. I request Apple Team To Resolve This Problem

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Oct 21, 2023 12:27 PM in response to Old Toad

Lol free diagnostic? They charged ne 30USD for inspection and told me that 650USD is required to replace the screen. I did the diagnostics there are no problems, display just fails for iMac 24 inch.


It's a problem faced by many, Apple product failed multiple times in a span of 2 years, I could now have brought another iMac with repair cost. This product had a logic board failure during warranty period and apple denied replacement, now this. Any way I have to buy new one now for my work ( Let the stock raise lol )


Similar issues are being faced by many, so why denying it?

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Nov 22, 2023 3:38 PM in response to latVm

I am also surprised with the same sudden horizontal lines in screen. I am participating in hackathon and this is giving me nightmare as it’s all sudden and cost is just way too much..


since all of us started experiencing this issue after wwdc23, am wondering if some software is burning the part or some weird thing that is affecting the iMac.


this is just too soon and very very similar to not be a coincidence.. since my iMac is out of warranty too, I am just too scared to even visit service center..


many of them just want to replace parts, get money money money, that’s it. Did anyone managed to resolve issue without burning so many $$$$? (In my case, it’s ₹₹₹₹₹₹₹₹₹₹₹ and almost all my saving so far 😞😞😞😞😞😞)


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Persistent horizontal lines appear on iMac screen

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