Persistent horizontal lines appear on iMac screen

To make the best of a bad situation you could always use a separate monitor with the iMac. It's an annoyance given that there's already a display taking up desk space but at least you wouldn't have to get another computer. I kept several older iMacs going that way. Just make sure that if the display is really starting to go that you set this up before it is fully gone. You set up the second display as mirroring the first one and with iMacs this has to be done while you can still navigate the main display.

Is Apple not aware of this issue or just trying to ignore? I am also located in Singapore, went to Apple Service Center last Sept 2023 and was quoted of SGD900++ to fix the issue. Very expensive and this is not caused randomly by any mishandling, this is really an issue on Apple's hardware and design of this iMac model.

I did not proceed to have it fixed, I just bought a second hand monitor and attached to this iMac for just $100.

But then again, Apple should not ignore this. How we can make this a trending topic in Social Media? Once this trends, I am sure Apple will do something as that will affect their future sales.

Any suggestion to make this trending? Maybe we can post a video in Youtube and TikTok?

It´s a hardware issue.

But, because the (1 dollar) component it's causing it is not accessible, the only fix is an all-new (600-800 dollar) LCD.

My advice, at this moment, is to get a second monitor and turn the brightness of the iMac monitor to ZERO to protect it and delay its definitive failure as long as possible.

A 4K (27”-28”) monitor, with 350nits (or cd/m2) minimum, should work fine.

Color calibration will be the biggest problem if you buy a cheap monitor, but I was taught a trick which is to use the iPhone (or iMac monitor) to do it easily, by matching the monitor to the phone (or iMac) display. There are several videos to help with this technique.

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.

@jot hey - here is how:

1. I used the normal support channels, to speak to the support through chat
2. In the chat conversions, I requested to be transferred to a senior representative regarding a special situation that I need the highest level to be able to help me.
3. I was then scheduled a call with a "senior representative who I Katherine"

Key points:

1. I kept doing forgiveness work, releasing apple and the situation and I became willing to let it go if they are not willing - so I wasn't coming from an angry voice tone, but from a calm, and genuine voice tone of wanting to fix this together
2. I made sure I am being calm and I expressed gratitude to apple and told her how I spent over 7K in the past year alone,
3. She already had seen this thread and she knew and agreed something is not right.

Realizing Apple is a multi-billion dollar company and they really do stand behind their product, now there is enough evidence here for them to help those of us in need.

MacBooks with FlexGate have similar problems. In the MacBook, this is caused by the LVDS cable, which is fixed to the PCB of the lcd assembly and not easily replaceable.

However, the LVDS cable in the iMac can be replaced. Has anyone had experience with this or replaced this cable before?https://www.ebay.nl/itm/255809013613?mkcid=16&mkevt=1&mkrid=1346-175129-2357-0&ssspo=9_Kc3GPRQIS&sssrc=4429486&ssuid=2ViFqcZVSqK&var=&widget_ver=artemis&media=COPY).

I just received my repaired Imac. every thing looks beautiful and it is just like new! It only took 3 days total to fix and I paid zero :)

I am very thankful.

Overal process:

1. Kept apple in good consciousness and practiced released judgment and frustration and remained in forgiveness and non-attached frequency. 2 Reached to chat support and requested senior advisor 3. Had a genuine conversion about my appreciation for apple and how there is a case of manufacturing that can be happy to any company and requested for them to investigate this thread - as it is well documented. (Thanks to all of you) 4. She forwarded it to engineers and requested the photos and files from me, and within a few days had been approved for repair.

I trust this can be done for all the other people with the same issue and hopefully in the future if it happened again they can upgrade us to a newer model. May be we can all get an M3 ? :P

Talk soon!

There might be a connection between auto-adjustment of brightness and the onset of flickering. My iMac first had the flickering one week ago. I turned it off and on. The flickering disappeared, but a black line persists. Since then, the flickering appeared a few times more. It seemed start when there's a change in environment light. For instance, I pulled down the curtain. My room became darker. The brightness of the display changed (I had auto-adjustment of brightness on). Also appeared flickering. I then disabled auto-adjustment of brightness. Flickering hasn't re-appeared since. Just to share my observation, in case it might be useful.

My screen started flickering two days ago, June 18, 2024. I got my iMac 24' on March 14, 2022, with an M1 chip. I read the entire discussion. It is, for sure, Apple being sloppy, faulty and even rudely arrogant. Nothing else. They want to enforce Apple Care.

All screens went terrible after two years and a few months.

It begins with patchy flickers here and there, keeps widening and covers your entire screen, making your iMac unusable after a few days.

I would suggest getting a decent external screen. Ditch this old one. No use getting it repaired with no warranty and a one hundred per cent certainty that the replacement will also bite the dust after two years. And APPLE DOESN'T CARE at all! They want money. No accountability.

Dear Alok Mishra,

According to someone, apparently, the problem lies in a cable that also powers the LCD.

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.

After a while (in this case after about 2 years) it starts to burn out and degrade at the connector side, 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 "ghost" we see is the signal bleeding from one line to the other due to the short circuits caused by the heating and cable degradation.

That was explained to me by someone who is a technician. But because I'm not a technician, the explanation may not be 100% precise. But I think it's quite accurate and clearly points to a hardware fault.

Hi everyone. Please be sure to report this issue directly to Apple via the Support Chat at https://getsupport.apple.com/solutions. They now have an Apple internal tracking number to capture reports specifically for this display issue on the 2021 iMac. If all goes well, this is a pre-cursor to an official out of warranty free repair program.

I learned about this while at the Genius bar with my 2021 iMac. The tech showed me the info on his support device that this issue is being tracked under an official Apple support issue number. It was like EF something. Anyway, DEFINITELY REPORT THIS ISSUE DIRECTLY TO APPLE SUPPORT!

Hi everyone. As promised, here's my story of getting a replacement iMac without paying money but effort and time. I'll only present below the timeline of my story and a few comments for brevity (since what I have done is as same as what have been told in this thread):

• June 2021: bought iMac M1 in Spain. I didn't purchase AppleCare because Spanish law provides 2 year warranty (later even extended to 3 year warranty). Since iMac always stands at one place, meaning little risk of accidental damage, double insurances for 2/3 years (AppleCare + warranty provided by law) seem excessive
• May 2024: flickering horizontal lines suddenly appeared in the screen (totally out of blue)
• Soon visited Apple Genius Bar to ask about solution without bringing in my iMac, and was told the screen needed to be replaced on my cost
• September 2024: visited again Apple Genius Bar and brought my iMac with me. The staff examined my iMac and suggested the same solution as before
• October 2024: contacted Apple via chat, and was given a phone call, where talked to a lady first, and then a senior advisor. As result, no change to the solution offered
• Afterwards wrote a formal feedback to Apple about my iMac
• End of October 2024: suddenly received a phone call from Apple, asking to have a session in order to collect some information about my iMac. System metrics were collected during the session. I was told Apple would analyze the information and decided what to do.
• 2 weeks later, Apple called me and told me that they would like to collect my iMac and provide me a replacement with no cost. The model of the new iMac would be as close as the old one. However, they can not be identical in my case: M1 is not available any more, M4 instead; the basic keyboard of the new model does not have touchID; the basic adapter does not have ethernet interface
• January 2025: I received the new iMac today. It's as expected

Thanks to everyone who contributed to this thread! You guided me step by step in this journey. Wish all of you get a replacement!

I planed buying a few Apple products but halted my plan due to the shock caused by the iMac deficiency. I'm happy I can buy Apple again after the replacement!

My advice is to turn off the LCD lighting on your iMac (set it to 1).

By reducing the brightness you'll be able to see that the temperature at the top of the LCD becomes normal and the worry about over-temperature will disappear.

Then buy a new external monitor.

There are very good monitors available relatively cheaply.

I worked like this for almost a year when my iMac was broken and without any problems.

It's the same as having a (very expensive) Mac mini...

But at least you can keep working until Apple sort it out.

UPDATE

I faced an overheating issue in the top right corner of my 2021 M1 iMac 24”, which eventually led to display failure with burn marks and a smoke smell after 2.5 years of usage. Initially, Apple India denied free repair as the device was out of warranty and offered only paid service. I escalated the case to Apple USA with proof that this was a known horizontal lines issue (widely reported in forums and media) and highlighted the severe safety threat to my family. After sharing high-resolution photos, videos, and diagnosis reports, and insisting on escalation to their engineering team, Apple granted me a one-time exception (CS Code) for a free display replacement. 🙏 After 90 days of usage with the new display, it is working completely fine, and I sincerely thank Apple for their credibility and for standing by their customers in critical situations.

UPDATE: I got Apple covered the display hardware fee

Here are my suggestions to whom having the same issue.

1. Make a Genius Bar appointment for further examination. Genius Bar will mark a note if there were any visible abuse/damage to the product. Note: Authorized service providers can also examine your iMac but will incur a fee even you decide not to repair.
2. Share with the Genius the evidence you have. Ask for a free repair politely as the issue is so widespread. However, don’t expect any positive result from here. This is only for recording purpose.
3. Reject the expensive repair cost quotation, and bring the iMac back.
4. Get online support. Give the 1st level advisor the related links, including this thread, to show this is a widespread issue.
5. Ask the 1st level advisor to escalate to a Senior Adviser. The senior adviser will call you by phone. Ask him/her to read the links you sent earlier first.
6. Insist a formal written reply explaining why this issue is so widespread, or Apple think this is just independent cases. You will get a case ID for this.
7. Use the same case ID, repeat step 5 to 7, in a week or two.

Don't forget to send product feedback from Apple's website, so hopefully it grant an official Service Program one day.

Good luck.