mokong1106

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.

Air ATD using A cable.png

Second image, Air using external cable connected to B. B built in cable connected to A. works OK.

Air ATD using external cable on B.png

 

Third image, Mac mini using external cable connected to B. B built in cable connected to A. works OK.

Mini 2012 ATD using external cable on B.png

 

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

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Q: Thunderbolt display - ports not working. Only the display works.

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  • Helpful answers

  • by mokong1106,

    mokong1106 mokong1106 Jun 9, 2016 7:10 AM in response to mokong1106
    Level 1 (4 points)
    Peripherals
    Jun 9, 2016 7:10 AM in response to mokong1106

    Here's another weird combo:

    Air -> using A built in cables

    B -> using built in cables of B attached it A

     

    I have a lighting cable to charge my iPhone attached to B which is working fine. But as soon as I attached the built in cables of A to air, suddenly the power goes out.

  • by tbirdvet,

    tbirdvet tbirdvet Jun 10, 2016 4:55 PM in response to mokong1106
    Level 4 (3,008 points)
    Jun 10, 2016 4:55 PM in response to mokong1106

    The TB cable carrys all the power for the display and the ports.  It is possible that the built in cable is bad even though the display works.  The circuit that feeds the TBD ports could be bad.