Mac Mini Won't Recognize 2nd Monitor through Thunderbolt Port

Hello,

I am a first time poster and unfortunately I have an issue on my hands regarding a problem with my dual monitor set up which has come out of no where.

I have a Mac Mini (Late 2012) 2.6ghz i7
with OSX 10.8.4

I have been running a dual monitor set up since the Mac Mini was purchased about 2 months ago and have no problems. One monitor is connected through the HDMI port and the other is connected with a MiniDisplay Port to HDMI adapter.

Suddenly I wake up this morning and the monitor connected to the MiniDisplay tells me I have no connection. The monitor connected to the HDMI port works regardless of which HDMI cable I use or which monitor it is plugged into so I know it is not my cables or my monitor.

I have tried putting the machine to sleep and disconnecting, shutting down completely and booting back up connections the monitors one at a time and I still get no connection through the MiniDisplay Port. Oddly enough when I connect or disconnect the MiniDisplayport adapter (if the computer is running), the screen attached to the HDMI port turns blue which leads me to believe that it is not my MiniDisplay Port or my adapter causing the issue.

Does anyone know of a solution? Has anyone else had this issue? I have been spoiled with two monitors for far too long to keep this charade going.

Thanks,
Rizz

Rizz said:

... The monitor connected to the HDMI port works regardless of which HDMI cable I use or which monitor it is plugged into so I know it is not my cables or my monitor.

...

Click to expand...

If I'm understanding the above...

Both monitors work with either HDMI cable as long as it is plugged into the HDMI port on the mini

and

neither one of the monitors work with either HDMI cable when plugged into the mdp to HDMI adapter / TB port?
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Try these one at a time.

If you've done all that, pretty sure you've unplugged the mdp to HDMI adapter from the mini and plugged it back in - if not, do that and try both HDMI cables.

Boot into safe mode - Don't need to do anything there, just allow it to boot up all the way and then reboot normally.

Do a SMC reset.

Get a new mdp to HDMI adapter.

(Just because the machine recognizes something is plugged in when you plug in the adapter, that does not indicate the adapter is fully operational. That would indicate your Mac is functioning correctly and is attempting to send a signal because it recognized a new cable being attached.)

edit:
And have to state the obvious - make sure the monitor is set to the correct input... e.g. it has not mysteriously decided to change itself to a different input.

Hello,

Greatly appreciate your response. I have tried all of the above (except buy a new adapter) and haven't found a solution. However I will say that yesterday I turned on the machine and both monitors worked fine from start up except that the arrangement was switched around.

Does that change anything?

Thanks,
Rizz

It does point to the probability that it is one of the connections (or wiring inside one of the cables/adapter) that has to be in just the right position for it to work.
(Initially, could be that it works in more positions than it doesn't work, but it always gets worse.)

As long as it's working again, personally, I'd order an extra adapter and cable to have around for backup & testing.
If I am able to narrow down which cable is exhibiting such a symptom, I replace them before it gets any worse.
You can get another of each from Amazon or monoprice for a total of probably $12-20.