Horizontal lines over iMac 24 screen

Hello Lat V, I'm having definitely the same problem with you. As I find your post here, I wonder if it is a Quality control issue cuz I bought this iMac in August 2021.

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, 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), has to sustain a very high voltage (around 50V) to power the LCD (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.

To figure this out you need an external display. Does the effect show up on it? If it does the logic board will need replacement, if the image is clean that proves the display is bad.

When did you buy the system? If you know what is your countries warranty period as well.

Where do you live? Country and nearest major city. Also do you have access to an Apple Store as clearly this provider failed you.

I am having the same problem. I've had this iMac less than two years. These lines appeared a couple weeks ago and have shifted a bit but haven't disappeared. From what I'm seeing online, we are not the only ones experiencing this. This is not right. Apple should be held accountable for this issue.

I have same experience with this problem, i had bought this imac 24" base model on 2021 November in Yogyakarta Indonesia, and have this problem like this:

and

after I bring to Authorized Apple Service Provider in my town, they diagnosed that my display must be broken and need to replace, they charges me around 810$ (13million IDR) so I canceled it because it's not worth it, after I bring back and turn it On again on my home, the screen only have tiny horizontal and vertical lines on the corner like this:

does anyone have experience like this before? or is it because the cable that connected the display and logic board inside?

I bought my M1 iMac in Hong Kong about 2.8 years ago. Flickering lines just appeared weeks ago.

Really disappointed on the Apple product quality this time.

Any blogger/influencer here that can highlight this issue? Apple is playing deaf and blind.

Hey @latv, i am from bangalore, india. Having the same issue. What did u do at last? Even visiting store is not ideal given size of this box. Tell ur success/failure story of replacement, so i can visit the authorized store accordingly

I've got the same issue with the same symptoms: a 2-year-old M1 iMac bought in Singapore. Reported to Apple via the feedback form and posted in Apple Forums.

Now it started flickering so became very annoying and really unusable.

Having same issue after 2.6 years of using my IMAC M1 24". I leave in Mumbai, India. Took it to Apple store. They charged 2500 INR for checkup and gave 54000 INR quotation to replace new screen. Local service centers charging around 45000

Have anyone notice the top right corner of screen feel very hot when touched. I strongly feel its over heating issue or Flex cable problem. I would have opened and checked it myself but I dont have tools to open the iMAC and assemble it back.

hey friends!

I believe we can fix this together!

Your feedback seems to be making a difference.

I just got off a call with Apple senior advisor Katerine, she mentioned she sees the evidence and agreed there is something very unusual with this product. She is forwarding it to the engineers for investigation.

This can very well become documented and resolve this for all others in the future!

So please make sure everyone posts your cases at this link with your pictures. She said they don't care about other domains only the threads on Apple.com are taken seriously.

https://discussions.apple.com/thread/255...

Was not able to. I noticed that also last week, apple has locked it.

Was about to post that my iMac issue has worsen, now I have to put a heatsink since there is a spot in front that is very hot, it can burn my skin.

If Apple forums lock every discussion with no new messages in the last 7 days (ridiculous) I guess this topic here should be the main place for reports.

Please, everyone with the same problem, post photos with all the information about your model here.

This is VanCity From MacForum.

That was very sketchy how Apple locked the forum. There was an active conversion that same day, and they locked it. It was not due to inactivity, it was due to hyper activity and I assume some other back-end reasons they shut it down.