No signal to external monitor over Thunderbolt on MacBook Pro

Question

s1s0 Author

Level 1

4 points

No signal to external monitor over Thunderbolt on MacBook Pro

Trying to install external monitor (Philips 5K2K UltraWide Thunderbolt). The monitor comes with a Thunderbolt cable.

When I plug it to my MacBook Pro, the monitor complains that there is no video signal. By the way the computer is charging over that connection, yet no signs of any data exchange.
If I plug the same cable to a Windows laptop (USB-C port) - it's all working nicely including the camera, microphone etc.

Looked at System Info on the Mac, under Thunderbolt/USB4 tab. I can see:

40B1U6903CH:

Vendor Name: PHILIPS

Device Name: 40B1U6903CH

Mode: Thunderbolt 3

Device ID: 0x2

Vendor ID: 0x122

Device Revision: 0x3

UID: 0x8087FD6CA429AD00

Route String: 1

Firmware Version: 41.40

Port (Upstream):

Status: Device connected

Link Status: 0x2

Speed: 40 Gb/s

Port:

Status: No device connected

Link Status: 0x7

Speed: Up to 40 Gb/s

Any ideas? What I'm missing here?

Regards

Svilen

[Re-Titled by Moderator]

Posted on Jan 18, 2025 12:59 AM

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Answer 1

Jan 18, 2025 2:17 PM in response to s1s0

<< it is not showing me the external monitor in the display tab of System Settings. >.

then the display has not yet been recognized by the Mac.

The Mac does not rely on windows-like side-loaded "Drivers" which are actually packages of resolutions and settings for a specific display. Instead, it goes straight to the immutable source -- it asks the display itself.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

also, if you DO get the display recognized in the display tab of settings, if you lower the resolution to 4K at 30 Hz, do you get a picture?

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Answer 2

s1s0 Author

Level 1

4 points

Jan 18, 2025 11:04 AM in response to Grant Bennet-Alder

I'm not sure I can change anything when connected over the Thunderbolt:

From MAC - no chance, it is not showing me the external monitor in the display tab of System Settings
- ... the above despite the System info I reported in the first post
From the monitor - no such options in the monitor menus as far as I can see

If I connect over HDMI - ok, I can do that, yet it doesn't help the issue I think.

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Answer 3

s1s0 Author

Level 1

4 points

Jan 18, 2025 2:47 PM in response to Grant Bennet-Alder

Detect Display - didn't work for me
Insertion of the display cable (on both ends) certainly was not working, I did this probably a couple a dozen times
Sleep/wake-up didn't seem to be working as well, but to be absolutely honest maybe I didn't tried that enough times :)

Restart! ... got it working! (finally!)

... on the max resolution, with the max (75Hz) refresh rate.

Thanks for the help and support.

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Answer 4

Jan 18, 2025 5:03 AM in response to s1s0

Which MacBook Pro?

Is this the only external display? If there are others, what are they?

is it connected by a Thunderbolt cable (not just a USB-C one), and how long is the cable? I’ve read that recent versions of macOS do not like to see display transmission errors, and may cut resolution or signal if they see any.

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Answer 5

s1s0 Author

Level 1

4 points

Jan 18, 2025 6:44 AM in response to Servant of Cats

Apple M3 Pro, model Mac 15,7; OS Sequoia 15.2

That's the only external display.

The cable is Thunderbolt 4, which is coming with the monitor, but the situation is the same with Apple Original cable. The length of both is 1m.

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Answer 6

Jan 18, 2025 8:16 AM in response to s1s0

40B1U6903CH appears to be a 5120 x 2160 display with 10-bits/color capaibility(HDR)

Signal Input:

HDMI 2.0 x 2,

DisplayPort 1.4 x 1,

Thunderbolt 4 x 1

if you lower the resolution to 4K at 30 Hz, do you get a picture?

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Answer 7

Jan 18, 2025 4:43 PM in response to s1s0

Hurray!

good for you for staying the course and keeping up trying more things!

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