Cannot connect to external display new Macbook Pro 16"

Question

Cannot connect to external display new Macbook Pro 16"

Trying to call up LG external display on brand new Macbook Pro.

Monitor is connected via HDMI ports and turned on.

Instructions say System Prefs>Displays>Click on "Detect Displays" button.

???

There is no "Detect Displays" button.

If I hit the Option key, a little drop down called "Add Displays" appears in the lower left of the window.

It acts only as a dropdown to show what other Displays I might have added (like our Roku) but does not allow me to add/delete any other displays. It is not detecting the LG 34UC97, even though it is turned on, hooked through HDMI, and compatibility-checked.

Is the place to add or recognize another display somewhere other than DisplayS>Add Display???

What are we missing???

MacBook Pro 15″, macOS 10.13

Posted on Mar 26, 2022 4:34 PM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

132,997 points

Mar 26, 2022 5:43 PM in response to Rhythm Earthsong

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

• on invoking Option-(Detect Display) button in Displays preferences (from another display)

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

Modern Displays with multiple ports are sometimes busy scanning the other ports, looking for an input, and miss the query from the Mac. They need to pay attention to the port you are actually using, or they will miss the query.

Some displays have On-Screen Display settings that can be used to tell the display a computer is attached on a certain port, or a certain port should be highest priority. Changing those may make your display more responsive.

Some displays include their own private "sleep" settings for the display alone. This can allow the display to enter its own sleep mode, on top of the Mac's not sending it data. A display that is sleeping on its own cannot respond to the Mac's query, and will stay dark.

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Answer 2

Mar 26, 2022 6:39 PM in response to Grant Bennet-Alder

Tried 3 of the 4 suggestions (minus a hard restart.) No go.

With WIFi off, the HDMI is recognized by monitor. It says so right on the monitor screen:

"HDMI connection is recognized. Click 'OK' to switch to HDMI input."

Cool, except...the monitor does not have it's own separate mouse or cursor, and there is no 'OK' showing up anywhere on the Mac screen, so how can I click 'OK?' Attempting to move the cursor over to the external screen didn't work.

A menu or button called 'Detect Displays' does NOT show up in the Sys Prefs>Displays window, even when the monitor itself posts this message. Nothing shows up, even when hitting the Option button.

If I turn WiFi back on, I do get an extra menu in the lower left of the Sys Prefs>Displays window, but it's called 'Add Displays,' not 'Detect Displays' and it shows one already connected (our Roku, which is on our WiFi network, but is Not a display) and, as I said, does not show me any opportunities to add a display, no matter where I click or option click on that little drop-down.

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Answer 3

Mar 26, 2022 7:05 PM in response to Rhythm Earthsong

if the display is suggesting you change its input settings, you need to use features usually called "on-screen display" to interact DIRECTLY with the display, and change which port it is using. This information is in the display user manual, and sometimes in the setup guide as well..

If you post the exact model LG display, Users can look up the user manual, find that information, and make additional suggestions.

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Cannot connect to external display new Macbook Pro 16"

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