Target display mode blinking black

Today evening I took my macbook to Apple Store and tried to reproduce the problem with the same cable with new iMac and was not able to do so - with new iMac it works just fine. Looks like in my case it's the problem with iMac, maybe it's old and dirty and overheats or something like that.

After I updated Maverick on both iMac and Macbook Pro, I couldn't have a single blink so far this morning... it seems smooth so far.

I will update here if I start seeing it again.. but I think it's fixed.

If you still see issues with this, it's probably a hardware?

Never mind.. it's happening again :/

Although it looks like if I close the lid.. it works better.

After installing OS X Maverics to iMac and then istalling Thunderbolt update (it was in App Store updates) I don't see the issue any more

I think this is solved! I haven't seen the blinking for a while now...

I'm having the same problem. MacBook Pro Retina, 15-inch, Early 2013 and low-end iMac 27" mid 2011. My MBP is 10.8.5. Problem occurs more with increased CPU/GPU load. The iMac was 10.7.5 when the problem first happened. Updating the iMac to 10.8.5 did not help. Changing thunderbolt ports did not help. Cold or hot doesn't matter.

The MBP is from my job but I work at home sometimes. I've persuaded my boss to buy me a new external monitor for home to solve this problem. It would be really great to say the problem was solved with a free SW update instead (maybe I will get a bonu$??). Also I don't have room on my desk at home for an iMac 27" and an external monitor. But before I say "problem solved" to my boss, I am waiting for more "problem solved" postings.

Mavericks is next. Keeping fingers crossed!

Yeah, I haven't had the problem since upgraded both my MacBook Pro and iMac to Mavericks...seems fixed for me.

Same here.. I see it happening once a day now... less frequent but still happening.

I guess I just gave up at this point... let me know how I could help you get heard.. if you create a public list, blog.. or anything.

Just to let you know.. my apple care said they didn't have an issue at all in the first place... and that I should probably get hardware support or fixed...

It's really annoying.

Same for me - blinks about 2 - 3 times during one day

Hey Guys,

I posted on this thread early on and would like to let you know that my situation was caused by a loose connection on the LCD panel. I just got my LCD panel replaced because of another problem and now target display mode working without the random black blinking.

Just FYI to y'all....

I had mid-2011 15 inch MacBook Pro and now I have Early 2013 MacBook Pro 15 with Retina display. At my school library we have about 20-30ish Mid-2011 27 inch iMacs (we also have LOTS of late 2012 21 inch and 2011 21 inch).

Whenever I go to the library, I always hook up my MacBook so I can have more room to work on my stuff(via Thunderbolt cable) to the 27 inch iMacs. EVERYTIME, the display does this black blinking thing multiple times a day. It's not just one iMac. I think I've tried all the 27 inch iMac we have here at school and they all do the same thing. When it's blinking in black, my MacBook screen remains unaffected(it doesn't blink at all). It wasn't so bad when I was using the mid-2011 MacBook but after I switched it over to rMBP, it just got worse. But, when I use the iMac without connecting it to my Macbook, it works perfectly without any problem.

So I try to connect it to the smaller 21 inch iMacs(both mid-2011 and late-2012 model) and I think I had this blinking problem only once while using it for over 1 and 1/2 yrs (combining both MacBooks). So far, looks like 21 inch models don't have much compatibility issues with TDM.

First, I know it's not the cable. I went to the Apple store and told them about it and they just exchanged it with brand new one out of the shelf right away.

Second, I highly doubt that 27 inch iMacs are defective. I mean there are roughly 30 of them here and all of them do the same thing.

Third, I also doubt that it's my MacBook's problem. If it was my MacBook that was the problem, then it would blink badly while it's connected to 21 inch models as well.

HOWEVER, one very interesting thing I've noticed is that it seems to blink the most when the mouse usage is high. Especially when I click often. As I was typing this for about 20-30ish minutes or so, it didn't blink once. Normally, it would blink at least once every 10 minutes or worse.

I have a confident feeling that there's an issue somewhere in OS or the Thunderbolt firmware. Maybe it's not pushing enough power(or something) for this resolution due to faulty firmware setup?(Not that I'm saying that Thunderbolt's theorethical bandwith can't handle this resolution. I know it can handle this resolution with a breeze.) I mean I'm no Apple Engineer so I don't know exactly what the problem is, but like I said I have a good feeling that it's not the hardware issue. At least in my case.

Jarrod,

I have the same problem and talked to Apple a lot during the recent weeks. I also mentioned the cases referenced in this log and got the information that your problems are gone with 10.9.

Fot that reason I would be interested to have an update from you.

Anyway I built 2 fresh systems for a Macbook Pro Retina and the iMac, but still see the issue that the iMac starts flickering after some time being in target display mode and finally remains black. To recover I have to unplug the thunderbolt cable, plug it in again and switch to target display mode again. However, the procedure continues...

Thanks for an update.