Screen dims then gets bright randomly on Mac Pro Mavericks The trouble is that both displays randomly dim to black then fade back up to normal.  The intensity, pattern, and frequency of these events are all random.

I've read comments on how to turn off "auto-adjust brightness", but I don't have that setting in preferences.  This only started since I added an adapter for converting the video to composite on the secondary controller.  I suspect that the O/S doesn't know how to handle this adapter, and is attempting to use auto-adjust brightness due to this.

Is there a way to MANUALLY turn off "auto-adjust brightness"?
(i.e. a file I can edit to make the change)

Does anyone have any other idea as to what would cause this?
There's Brightness - freeware - but I don't know if it will work on a Mac Pro, which doesn't have any brightness control built-in, like the laptops &amp; iMacs do.

There is no adjustment at all on a Mac Pro Display Control Panel...



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