New 27" Thunderbolt Display Flickers when attached to new 27" iMac

It's a RAM issue. >8GB RAM causes flickers. Apple has acknolwedged this.

OK, I have 8GB. What now? Could you point me to the Apple document that ackowledges the problem.

TMX

While I would say the problem most certainly could be the port, as Cosman indicates, that's not my case. I can switch happily back to any number of displays via TB adapter. As for RAM, my MBPro supports 16gb but only has 8 installed from the factory.

The flickering started for me 3 weeks after the 12 month warranty ran out (couldn't afford the Apple Care). Then my monitor started turning off completely. Turning it off at the wall and on again after 5 minutes would get it going again. This got worse and I started mucking with settings, eventually finding that the brightness had an affect. If I had the brightness below half it would just stay on. 2 weeks of low brightness bliss, but then it started again and got worse. Over the past weekend I couldn't get it to stay on more than 5 minutes. Pretty sure this is not a ram issue at my end, so yesterday I finally took it in for repair. They ran the monitor for 5 hours no problem, then rang me and said they were going to replace the logic board as it was the only thing they could think of. For their best guess I would be nearly $300 out of pocket. However, they rang back an hour later, said it had finally switched off and that it was the actual LED display itself. It would need replacing. "How much?" I enquire. $1,250 he says.

Yes, I typed that correctly. $1,250 to replace a part in a monitor that cost $1,199.

Yay Apple.

...I'm very angry.

OK, I finally have something definitive. Let me give the answer first, then the rational. This pertains to the thunderbolt to VGA adapter, but has implications for all version of the flicker problem.

The problem is in the Thurnderbolt circuitry in the T to VGA adpter. The circuit inside is does not produce a high enough voltage to sync the display. The display may sync with the signal sometimes, and not others. The display will show a loss of signal, sometimes with a message, sometimes not. The disconnect will come and go since the signal is marginal and wobbles up and down somewhat.

This sync circuitry is in the adapter, but it is also inside any monitor, like the Thunderbolt monitor. I think the circuitry is flakey. Thunderbolt is a new technology and they didn't get it right in the first generation circuit design.

How did I figure this out. Not rocket science. I have an MBP, three monitors and two T/VGA adapters. All monitors flickered on all adapters. The MBP screen was unaffected. The response of the two adatpers was slightly different. One was a little better than the other. When one would start flickering, I would swap to the other.

I went to the Apple store with my problem. I took a video of the unit flickering up and down. They said it had to be the logic board in the computer. They swapped it out for another one. Same problem.

I went back in and talked to a different guy. He gave me a new adapter. Problem solved. Now I need to go back with the second adapter and get it replaced.

Apple needs to own this problem and fix it.

Thanks for the post Cosman. Yes yes yes. Apple needs to fix this garbage NOW. NOW. There has been no effort to stem this issue since day 1, and all signs point to their faulty engineering.

I've had the MBP 13" i7 + TBDisplay configuration going for some months now and the flickering never showed up before. Today, for the first time, I started experiencing this issue. The only think that changed since yesterday is the fact I installed the new 10.8.3 update. I didn't move or touch any hw in the previous days.

Hi guys,

You should gather on this thread, as many users have the same kind of issue:
https://discussions.apple.com/thread/3340067?start=195&tstart=0

Cheers.

Additional info:

As mentioned above, I exchanged one T/VGA adapter which solved the problem. The second one I took to work (forgot to take the good one) and didn't realize it until the display started to flicker badly.

I immediately logged in to the local Genius bar for an appointment. Went there over lunch a swapped out the second adapter.

Back at work everything worked fine. No flickering.

That pretty much proves the case. The circuitry in the older adapters was not designed properly. Let's hope the new ones hold up.

Thank you Cosman for the additional info. Using the original TB display cable directly into the MacBook Pro with no adapter. Maybe that's the cable's circuitry who is faulty, but it cannot be changed: it is built-in!! 😟

My issue was the same guys/gals. Only the TBD cable in the monitor direct to a brand new MB Pro Retina. So, no adaptors involved... it's a TBD.. meant to use the TB port. Just saying.

As for the threads... if you combine to one...that's one less thread for Mods to delete and one less set of google results when people go searching for why their TBD freaks. So, I'd keep them both.

docgoku wrote:

As for the threads... if you combine to one...that's one less thread for Mods to delete and one less set of google results when people go searching for why their TBD freaks. So, I'd keep them both.

I din't think about that... Keep both, or more, it makes perfect sense now 😎

RE: Thunderbolt displays vs adapters. I don't presume to know the internal circuitry of the thunderbolt electronics, but since both the adapters and monitors exhibit exactly the same problems, it leads to the conclusion that the thunderbolt circuitry is bad.

In the adapter, there has to be a translator to go from TB to VGA. In the direct link from computer to monitor, my bet is the guts of the monitor are the same as always and the TB signal has to be translated into the monitor protocol. Whatever that translation circuitry is must be flakey.

Keep pounding the forums until Apple announces their fix. Swappping adapters is a lot easier than monitors, and the newer ones I got (1yr newer) are OK.

BTW, Apple geniuses do not read the forums and are not up to date on all the TB problems. When I mentioned the forums to my local genius, he knew nothing about it. He was helpful and swapped out my adapter, but didn't know anything about the problem up front.

I guess until Apple sends out an official bulletin, they are not supposed to know anything.

I'd like to add that when the screen flickers, from the monitor speakers I hear buzzing noises like an electric short circuitry. Anyone else with this "symptom"?

Sorry for posting yet another thread to this post, but reading the many posts in this thread I am unsure which solution/approach will resolve the flickering issue I am experiencing.

I recently received a newish laptop with MacBook Pro for work

• 2GHz, Memory
• 4GB 1333 Mhz DDR3
• AMD Radeon HD 6490M 256MB
• running Mac OS X Lion 10.7.5

I have it hooked up to an older Cinema Display (2008) 24 inch

AMD Radeon HD 6490M 256 MB graphics

It flickers every 3-4 minutes and then eventually turns off. I went to the apple store and they indicated my computer is too fast for the monitor...but since I did not bring in the monitor to demonstrate the flickering, it was an educated guess.

Can someone confirm if this is indeed the case and/or if there is anything I can do to resolve this. I am trying to upgrade my monitor for work and they think it may be the video card in my laptop..which has never failed while projecting to an LCD projector.

Plead advise!