Macbook Pro 2012 15" external display no show via Thunderbolt dock

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Macbook Pro 2012 15" external display no show via Thunderbolt dock

2012 MacBook Pro connects to dual external displays through Thunderbolt dock. In System Preferences > Screen I can see the displays and arrange them, but both external displays went to Power Saving mode when connected. The Dock is TB3 and I am using Apple's own TB3 > TB2 adapter and Apple's TB2 cable.

When connecting the displays one by one using Mini DisplayPort - DisplayPort cable, both working fine. When using my newer MBP with Thunderbolt 3 on the same dock, both displays working fine. I've tried several things...

SMC, PRAM reset - not working.

Detect Display - not working.

Shutdown/restart everything - not working.

Pull out everything from the dock and plug in one by one starting with display - Not working.

Did the S-key sequence - not working.

The MacBook Pro is running macOS Catalina, I have an external disk with macOS Sierra and boot into it, same result, not working. Everything else on the dock works fine with that old MBP (USB mouse/keyboard, storage, ethernet), except displays.

What else can I try?

Posted on Nov 3, 2022 01:11 PM

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Answer 1

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Grant Bennet-Alder

Level 10

138,677 points

Nov 3, 2022 07:04 PM in response to lkshean

There is one more "oops"

That MacBook Pro 15-in 2012 model only supports ONE external display.

2nd Display Support: Dual/Mirroring 2nd Max. Resolution:2560x1600

Details: The maximum resolution supported on an external display is 2560x1600.

from:

https://everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-i7-2.3-15-mid-2012-unibody-usb3-specs.html

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Answer 2

Nov 3, 2022 06:15 PM in response to lkshean

The Apple ThunderBolt-3 <-> ThunderBolt-2 adapter is really fussy about the kinds of displays it is willing to support. In general ONLY ThunderBolt displays can be used with it, and no additional adapters.

About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support

I think there also may not be enough bandwidth in the ThunderBolt-2 ports on your old Mac. In total, each provides 20 G Bytes/sec, which does not seem like enough to support even two modest-sized displays.

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Answer 3

lkshean Author

Level 2

165 points

Nov 3, 2022 06:54 PM in response to Grant Bennet-Alder

Grant Bennet-Alder wrote:

The Apple ThunderBolt-3 <-> ThunderBolt-2 adapter is really fussy about the kinds of displays it is willing to support. In general ONLY ThunderBolt displays can be used with it, and no additional adapters.

About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support

I think there also may not be enough bandwidth in the ThunderBolt-2 ports on your old Mac. In total, each provides 20 G Bytes/sec, which does not seem like enough to support even two modest-sized displays.

🤣 Ya, possible, it is an old machine.

I saw the System Preferences > Screen showing all 3 screens (2x Dell and the laptop screen), thought it could be supported but somehow the Dells not getting appropriate signal that they discard and went to sleep. Anyway, if anyone have further idea what else I can do, please do propose.

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