Thunderbolt / 24″ ACD Compatibility issue potential workaround (?) UPDATED (X2)

July 30, 2011 at 11:53 pm Leave a comment

I tried calling Apple about my Thunderbolt / 24″ ACD issue, but that got nowhere.  They wanted to replace my Mac mini, not my display.  There are pages and pages of people with the random screen blank issue posting on Apple’s own forums, and it isn’t just the new Mac Mini, but rather every Mac made with a Thunderbolt port (starting with the MBPros that came out a few months back).  It seems obvious that it’s a problem with the display itself, but what isn’t clear is what Apple’s going to do about it.  So far, they haven’t actually done much, but promise a firmware update that never seems to materialize.

So, I decided to try something myself, even if it meant I wasted some money:

Atlona AT-DP200 DVI -> Mini-DP adapter  (If you want one, search Amazon, as they have them for about 2/3rds of this price)

I ordered one on Friday with Fedex Saturday delivery.  It arrived this morning, I hooked it up to the DVI output of my HDMI->DVI adapter that came with my Mac Mini, and things seemed to go well…

Everything was working great today until after I installed a memory upgrade on my mac mini late this afternoon (it also arrived today, but via USPS).

Prior to the memory upgrade, I had experienced ZERO screen blanks and ZERO horizontal video shifts for several hours of use, spread out over the day.  Then, while playing Civ V, I started having occasional screen blanks and video shifts, which even continued after I stopped playing Civ (though things seemed slightly better).  Strangely, these screen blanks were different than the original blanks I experienced.  With the original issue, the blanks take place for a second or two, then everything returns to normal until the next random interval.  The ‘new’ screen blanks were longer, and it sometimes seemed to take me doing something (mouse movement, pressing a key, or something) to get the screen to return.  Also notably, the Mini was making a lot of fan noise while playing Civ.

Just to recap the wierdness, original connectivity:
Thunderbolt Port connected directly to 24″ ACD = Random screen blanks (theoretically caused by Thunderbolt compatibilitiy issues)

New connectivity:
HDMI Port -> DVI Adapter -> Atlona Mini-DP adapter -> 24″ ACD = Worked fine for hours, then random screen blanks?

Since the common factor to the problem has been the Thunderbolt port, how can I possibly have similar symptoms when I’m not using that port at all?  It just didn’t make sense, so I started looking at everything a bit closer.

Eureka! (A little tentative here, but promising)

I figured out that the DVI connection to the Atlona wasn’t connected very well.  When I attached it this morning, it didn’t seem to want to go together very far, but perhaps I was just being too gentle with it.  Anyhow, I think that when I moved the mini for the memory upgrade  (pulling it out, flipping it over, unplugging the power, swapping the ram, then putting it all back) loosened the cable a little too much.  There was probably 1/8th of an inch of metal showing between the plastic portions of the connectors, as they weren’t screwed together at all.  The screws on one side didn’t touch the threads on the other!  I’ve now screwed the adapters tightly together.  I figured this out about 30 minutes ago, and haven’t seen any screen blanking since, whereas they had gotten to be pretty common before the connection tightening.

On further thought, the fact that both the Thunderbolt -> 24″ ACD issue and the HDMI -> DVI -> Mini-DP -> 24″ ACD loose connectivity issue have similar symptoms makes sense.  My connection was loose, so the ACD wasn’t always getting a good signal from the DVI port.  I think the vibration from the fan while playing Civ may have also contributed.  The theoretical Thunderbolt > ACD problem may be very similar, except not with a physical loss of connectivity, but a loss related to a protocol or timing issue.

Anyhow, I could be completely wrong, and my display could start blanking any minute.  The most logical thing to do is to continue testing, which I plan to do tomorrow.

UPDATED 7/31:

Alright, today I played Civ V for about 5 hours, and it was perfect the entire time.  Then, I exited the game and soon afterward, the screen blanked.  Perhaps this was related to the video mode switching or something…

Since then, my only other issue has been the screen not waking up once, which was resolved by hitting the Reset button on the Atlona.

While this adapter doesn’t seem 100% ideal, it does seem to have relatively few drawbacks to it.  If I relied on this computer for my income, I think this adapter would be acceptable.

UPDATED 8/28:

Had more strange issues with the Atlona.  Snow (like on an old Analog TV).  Sent it back.  Tried an Kanex C247d next.  It didn’t work as well as the Atlona, giving me screen blanks, etc. within minutes of hooking it up.  Sent it back too.  Working with Apple on a real fix.

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Entry filed under: Mac.

Mac mini (mid 2011) and 24 inch Cinema Display Running Snow Leopard under VMware Fusion 3.1.3 on Lion

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