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.

I know, in fact, Apple is already aware of this issue and is working hard to resolve it.

For now, it's collecting machines with defects in order to analyze them and understand what's really going on.

It's a really complicated issue, but Apple is doing its best to resolve it as diligently and urgently as possible.

It's a question of time, but as it's a complicated issue, it will take longer than usual.

The aim is to solve the issue, but because it is unusually complicated, it will take longer than expected and longer than all parties might desire.

But there will certainly be a solution.

Persistent horizontal lines on iMac M1 LCD screen

I am reaching out to share an ongoing issue I, along with several other users (> 120), have been experiencing with our iMac 24-inch models, and to seek a collective resolution by Apple.

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 after reinstallation.

• Avoided operating the iMac for a week: No change in the situation.

• The LCD main cables have been tested: The situation was OK.

• The LCD mainboards have been tested: The situation was OK.

• Various brightness levels were tested over long periods: The lines decrease in the affected area in direct relation to the brightness of the screen - less brightness, fewer lines; more brightness, more lines.

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 problem occurs around two years of use, mostly outside the warranty period.

• The support received thus far has been unsatisfactory, with no definitive solutions provided by Apple apart from a costly screen replacement suggestion (entirely paid for by the customer without any co-financing from Apple).

Apparently, the problem 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 seems to be to replace the entire LCD (LCD+main boards+screen glass).

Apparently, 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 (this despite the iMac's power supply being 15.9V), and it heats up a lot!

So, apparently 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, apparently, 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 it's already clear to everyone that apparently this is a design or manufacturing defect in this Apple model. But only Apple knows the exact answer.

So let's hope that Apple takes on this discussion and gives us all Apple customers an acceptable explanation and solution, at least contributing to part of the cost of the (overly expensive) repair of our iMac M1 computers.

This discussion is also on the Apple forum at "discussions.apple" (.com).

The title is "Persistent horizontal lines on iMac M1 LCD screen".

Apple clearly didn't like the direction the discussion was taking with the most voted answer. So they ended it. Even on a false pretext.

So anyone who is suffering from this problem, go and show your displeasure and ask Apple for a shared solution.

It doesn't make sense for them to profit from this fault if we're the ones paying for the entire repair.

At least Apple should share part of the cost of replacing the LCD.

I know, in fact, Apple is already aware of this issue and is working hard to resolve it.

For now, it's collecting machines with defects in order to analyze them and understand what's really going on.

It's a really complicated issue, but Apple is doing its best to resolve it as diligently and urgently as possible.

It's a question of time, but as it's a complicated issue, it will take longer than usual.

The aim is to solve the issue, but because it is unusually complicated, it will take longer than expected and longer than all parties might desire.

But there will certainly be a solution.

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've started a petition urging Apple to acknowledge the M1 iMac display defect and provide free repairs for all affected devices. If your iMac is showing these symptoms, or if you believe Apple should stand behind their products, please consider signing and sharing: https://change.org/imac_m1_screen

Together, we can help bring attention to this issue and push for a proper resolution. Every signature helps show Apple this isn't just an isolated problem.

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.

Just posting that I'm having the same issue after 3 years (2021 M1 iMac), and want to keep an eye on this thread. No luck with Apple Support, but it's helpful to hear from others experience.

I have the same problem only 2 year of use! I'm disappointed. I've been using Apple for more than 30 years since my 8500 and the quality of the products is getting lower and lower... they think about the design but it's not the usability and durability of the product!

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.

We got that error too but we fixed it in just 1hour.Apple authorized service can't even fix this in our Country but user sent us and we fix that.

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