2017 macbook pro power issues with thunderbolt display

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Level 1

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2017 macbook pro power issues with thunderbolt display

i have a 2017 macbook pro with 4 usbc ports. all works fine with one usbc port for the power adapter and two ports for two 27" hdmi displays with the apple hdmi to usbc adapters.

i recently acquired 2 27" apple thunderbolt displays - two wires coming from the display 1 for power to the wall socket, the other with a split old time macbook pro power connector, the other a thunderbolt.

i get the mac thunderbolt to usbc adapter and plug it in to an unused port on the macbook pro. the monitor does not come on. when i remove the macbook pro power adapter usbc cable, the monitor comes on.

how an i power my mac with the supplied usbc power adapter AND use the thunderbolt display at the same time?

MacBook Pro with Touch Bar

Posted on Oct 15, 2019 3:29 PM

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Answer 1

t.moe

Level 4

1,221 points

Oct 16, 2019 7:11 AM in response to dandabble

I’m a little confused by your terminology - by Mac Thunderbolt two USB-C adapter, do you mean Thunderbolt 3 to Thunderbolt 2 adapter?

Also, when you say “When I remove the MacBook Pro power adapter USB-C cable - the monitor comes on?” Do you mean that the display works when you disconnect this cable (i.e., you have another cable hooked up for video).

If you are connecting the USB-C ports on the MacBook Pro to the USB ports on the display, they will not provide nearly enough power to charge your computer.

At any rate, there isn’t any way to power the MacBook Pro from the Thunderbolt Display that I’m aware of. Someone out there might have a MagSafe to Thunderbolt converted but I haven’t heard of one.

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Answer 2

dandabble Author

Level 1

8 points

Oct 16, 2019 12:24 PM in response to t.moe

thank you so much for responding! let me try to clear up the request.

i have a macbook pro that i use power from the usbc power supply that came with the mac.

im trying to connect two 27" mac monitors that have thunderbolt connectors. each monitor has it's own power cord that is plugged into the wall.

since the macbook only has 4 usbc ports, i had to get thunderbolt to usbc adapters to connect them to the macbook.

the problem is, when i connect either of the mac monitors to the macbook pro, they do not work unless i remove the usbc power supply from the macbook pro. when i do this, the monitor is recognized by the macbook pro and comes on.

the question is, why would the thunderbolt displays that go through the adapter to usbc be incompatible with just trying to add the power supply to the mac?

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Answer 3

t.moe

Level 4

1,221 points

Oct 16, 2019 6:04 PM in response to dandabble

They shouldn’t, if I understand your set up correctly.

To reiterate - you have two Thunderbolt 3 to Thunderbolt 2 connectors; you connect them directly to the Thunderbolt monitors and they work; then you plug the power adapter into the MacBook Pro and the displays stop working.

You can try and change the topology a little - put the power supply on one side and the displays on the other, that kind of thing.

I *think* you can also daisy chain the Thunderbolt displays - plug the second display into the first one - and see if the makes a differences.

But as far as I know what you are trying to do should be fine.

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Answer 4

dandabble Author

Level 1

8 points

Oct 17, 2019 12:56 PM in response to t.moe

by restarting the mac, the problem with the power usbc and the monitors went away. i did have to daisy chain the 2nd monitor off the first one to get all to work.

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2017 macbook pro power issues with thunderbolt display

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