Q: Thunderbolt display - ports not working. Only the display works.
Thunderbolt display - ports not working. Only the display works.
I have 2 ATDs. Let's call them A and B. I just bought A yesterday (used) from a friend. It worked for 2-3 hours with no problems. I also daisy chained it to B. I checked all of the ports are working etc. Tested it using 2012 mac mini and 2013 11inch air.
Just this morning as I'm watching youtube it suddenly displayed garbled image that I had to restart. After restart, A wont start anymore (black screen, B is OK). I changed cables to no avail. A is always black. Im using the built in thunderbolt cables of A and B.
Using the built in cables of A, I connect it to my air, the display works fine but the ports of A doesnt work at all(LAN, usb, no pusb power etc). This is weird. I talked to apple support and he said it might be the cable. If this is a cable problem how come I have a working display?
I checked the system report and it detects both display. first image I'm using my Air connected to the cable of Display A. A is blank. B is working.
Second image, Air using external cable connected to B. B built in cable connected to A. works OK.
Third image, Mac mini using external cable connected to B. B built in cable connected to A. works OK.
Good thing I have an extra Apple thunderbolt cable to test. After hours of switching cables, here's the setup that works for me by not using the built in cable of A:
Mac mini -> using external apple thunderbolt cable
to
Display B thunderbolt port -> built in thunderbolt cable of B
to
Display A thunderbolt port
All of the ports of A and B are working here. If I used the built in cable of A in the daisy chain wether at the start or end of the chain it will go black. I tried SMC, PRAM resets but still the same.
I know the post is long but to summarize:
without daisy chain-
If connected directly to a mac using built in cable, Display A is working but the ports behind are not.
with daisy chain-
To function properly, display A must be at the end of the daisy chain to work and the built in cables should not be used (external cable needed).
thanks!
Mac mini (Late 2012), OS X El Capitan (10.11.5)
Posted on Jun 9, 2016 7:09 AM


