I have the same configuration and sounds like I have a similar problem.
The display goes black, but I can still hear sound and I THINK the Thunderbolt HD continues to work, but I haven't tested it exhaustively.
I did pull the Thunderbolt HD out of the diasy-chain, just to eliminate that variable, but the Display still goes black every so often. Requires a reboot or power-cycle of the Display.
I have a similar setup and problem. My Thunderbolt display (refurb, purchased in February 2012) will randomly turn off, as if it went to sleep - but mouse/keyboard input does not wake it back up. The internal speakers will still output audio. Disconnecting/reconnecting the Thunderbolt cable from the attached Mac Mini (2.5GHz dual-core Intel Core i5, OS X 10.7.5, AMD Radeon HD 6630M ) will not resolve the issue. Disconnecting/reconnecting the display's power cord and the Thunderbolt cable from the Mac Mini will resolve the issue temporarily. This began happening maybe a month or two ago, and has probably happened 10 times in the last 30 days. It is completely random, and I have yet to be able to duplicate it on demand.
Steps taken to attempt to fix the issue:
Confirmed Energy Saver Settings
Confirmed Software up to date (OS 10.7.5)
Attempted Firmware Updates (message states not needed)
Reset SMC (unplugging computer)
There are other discussions reporting similar behaviour:
As well as other discussions concerning random flickering issues with the display.
Since I'm still under warranty, I took my display to a Genius Bar today. The rep didn't really seem to want to hear about what I found on these discussion boards. He says you can pretty much find anything you want to find here, and since it is unmoderated it is not a reliable source of information. I let him know that the issue (as far as I can tell) occurs with different models of Mac Mini's, MB Pros & MB Airs, suggesting it is in fact an issue with the display and not what's connected to it. I added that most folks who reported bringing the displays in for service ultimately ended up with a replacement display, as the service done on the defective display proved to not resolve the issue - but I would of course defer to his judgement.
He decided that they would order and replace the LCD panel. He assured me they would keep the display powered on for 12-24 hours after the service to ensure the issue has been resolved. Truthfully, I am not optimistic. And for the amount it costs to replace the panel ($833.32 from the provided estimate), I speculate this course of action will end up being much more costly for them in the long run. But we shall see!
I will be sure to provide updates as they come. Wish me luck!
February 7th, 2013
I am joining the ranks of concerned TBD owners. I recently purchased a customized beefed up 27" iMac with the fusion drive and high graphic card, love the machine. I thought to add a Thunderbolt display to it as a second monitor. As I have worked with two monitors since the beginning of its option. A second monitor is like a second arm to me, I need it. Anyways, I am having this cursed problem you all are having, my TBD does not wake from sleep. I hope it is an issue that can be fixed in software someday, but idk. For now, I will just learn to power off my machine after use if I am to be away more that 3 hours, an act I feel forced upon me. I am going to call Apple so the issue is logged with them officially and dated shortly after purchase. This Thunderbolt display and iMac were just purchased and recieved the last week of January, 2013. So the problem still exists as of then. I am all things Mac, sometimes it gets hard, but it does with any vendor, I know. So I will faithfully stick it out for a while before dumping the Thunderbolt display, which is awesome when it works properly. I wish Apple would respond on this issue instead of hiding behind their hallowed gates. It would be nice to get some official word on this matter.
Just an update to my previous post.
I was notified that my display was ready for pickup on Wednesday. I picked it up today and reconnected my Mac Mini. As stated previously, the issue (for me, anyway) is completely random, so I cannot confirm whether the issue has been resolved completely or not. I will post a follow up in a week or so to keep the community updated!
Good for you - I had only my second hiccup with my ATD the other day - cable main came to install new super-fast modem, everything was working well and I thought my Display had just gone to sleep... nope, the cable guy had unplugged the power port on my MacBook Pro. Simple fix, I though - just plug the MBP back up. But no... it took unplugging the display twice to get it back up.
I know how scary these moments can be - hopefully, yours is 'fixed' permanently now!
I had the same problem. Just bought a new TBD unpacked it, and connected to my MBAir. Everything was fine. The next day I tried to connect my MBAir again and it did not work. Started to check everything. Everything seemed to be fine. Thought I would have to return it, but then I read these posts and tried something that clintonfrombirgmingham mentioned, ie, disconnected all cable from the TBD and unplugged the display from the electricity. Waited a couple of minutes, turned it on, connected the tunderbolt cable to my MBAir, and surprise, it worked. Let's see how long it stays like that. Let's hope it is just a hiccup.