Chosen Solution
I have a thunderbolt display which does not display on power up. Is this a common fault and can it be fixed?
Believe it or not, try plugging the display directly into the wall instead of out of your batter backups or power strip. Plenty of people out there (including me) have found that there is a problem with the power supplies on these displays where they suddenly don’t like the power conditioning from certain power strips.
Try a different source - see if the problem still exists. Check the source with a different external monitor to eliminate a bad GPU as the cause. If this answer is acceptable please remember to return and mark it accepted.
Someone on another board recommended to test the power coming into the logic board, to see if the power supply is provided the necessary 23~25.3V required. Using my multimeter, I confirmed the logic board is receiving the correct power. Now I suspect it’s something related to cold solder joints, I just don’t know what part of the logic board to concentrate on. I looked it over, but I don’t have access to an X-ray type machine to examine cold solder joints. Any idea where I should just blindly fix the solder points to fix the backlight issue?
I bought a brand new Thunderbolt Display in 2011 but have not used it. Tried using it today and it does not come up when I attached it to the MacBook Pro and the iMac. There is no light on the Macsafe power supply to the MacBook Pro and when I connected a mobile phone to the USB port, it was not charging. I have tried several power sources but no improvement.
