Chosen Solution
I have a TB display that has been giving me some issues for a while and i have decided I’d like to fix it. Mainly i know it’s either a logic board or PSU issue, but don’t know which one I should replace. My TB display turns on and after a few minutes the display will go black (no, not just the backlight). The hub still works (all my usb devices), my macbook still recognizes an external display is connected, my speakers still work, and magsafe still charges during the blackout. If i unplug the display from the wall and back in, it usually will start right up, and then shut off within 3-5 minutes. I have tried a different TB cable, same issue. Do you guys think it’s a bad PSU, or a bad logic board?
If your display is not displaying at all, yet the USB & TB ports are still active (power & data) then you have a hard problem to isolate as all three major modules are suspect! It could be the power supply, logic board or even the LCD panel its self. You will need to find the schematics and board view for the display and then using a DVM test the voltages of the power supply and test the thermal sensors in the display and logic board. And lastly check the voltages on the logic board. You could try replacing the logic board to see if that’s the issue as it has the decoding logic to convert the TB signal to the needed video signal for the display. But that is still a hail-mary.
