Mini display port to USB C stopped working (no signal to monitor) - fix

I just wanted to share a solution I've found. I connected my DELL monitor to my new 2018 MacBook pro with a mini display port to USB C adaptor and at first it worked but after unplugging it a couple of times it stopped working. No signal to monitor. I tried a different port and it worked again, then stopped again and finally I could not get anything to work. Baffled and extremely frustrated, I tried everything. Finally I decided it was the connection between the adaptor and the cable. I then tried putting a fork (yes just a simple metal fork - the food kind) to each connection to remove any static electricity and then reconnected and it fixed the problem. It works without fail every time.

Posted on Nov 21, 2018 4:55 PM

Top-ranking reply

Grant Bennet-Alder

Level 10

141,661 points

Posted on Nov 21, 2018 7:32 PM

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, no data will be sent to the display.

This query is only sent at certain times:

• at startup

• at wake from sleep

• 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

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.

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Mini display port to USB C stopped working (no signal to monitor) - fix

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