Apple Thunderbolt Display Power Supply Replacement (Buzz Kill)
My Apple Thunderbolt Display was buzzing for a couple of years. At first it was slightly annoying, but lately it got really loud, to the point that my wife noticed it walking outside my home office.
I ordered the Apple part number 661-6048 power supply (google it, there are lots of vendors), followed ifixit's instructions and in short order I was buzz free.
Be very careful with disconnecting the cable inside, use a spudger and squeeze the connectors to release the locking tabs. The locking tabs are hard to see on the circuit boards as they are facing away from your view. Use a right angle or short torx T10 driver to get to the cable connected with a screw.