External monitor - no signal

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Level 1

8 points

External monitor - no signal

Hi,

Since I have updated my MacBook Pro 13 2018 to Catalina my external monitors stopped working properly. Mostly like 95% of all working time there is information "no signal" on my external monitors both are "aoc i2481fxh". Monitors are connected threw proper HDMI into female HDMI -> male usb c converter than directly to MacBook. Sometimes when im working for few hours on MacBook with monitors still connected one of them (randomly) starts working until I will shut down MacBook.

All apple suggestions of unplugging or restarting etc are not working. Trust me I have tried everything. Also I have checked separately HDMI cables, HDMI usb c converter, monitors and all ports in MacBook.

MacBook Pro 13″, macOS 11.1

Posted on Dec 30, 2020 10:23 AM

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Answer 1

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BorysJ Author

Level 1

8 points

Dec 30, 2020 11:24 AM in response to Grant Bennet-Alder

AOC I2481FXH - 23,5'' (1920 × 1080) both the same.

Both HDMI cables were attached to this monitors simple HD HDMI 60Hz.

Both converters are "https://www.morele.net/adapter-usb-maclean-usb-c-hdmi-bialy-mctv-841-4182202/"

The thing is it used to work for over 1 year with no problems and after Catalina update most of the time it's no signal on external monitor.

Right now when im writing this one monitor started working and second one is still black with no response.

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Answer 2

Dec 30, 2020 11:59 AM in response to BorysJ

What seems to be happening with these is that later versions of MacOS are querying the display, asking about data transmit errors. If the display is seeing any transmit errors, the interface is not engaged.

If you can get that display working consistently at a lower resolution, it supports the guess that the display adapter and cables are not of sufficient quality to support this resolution absolutely PERFECTLY.

The cables you want for HDMI-only Monitors (higher resolutions than HD TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"

HDMI Adapters that are trouble-free may be more expensive than the ones you are using, and are often rated for "4K" operation, regardless of the resolution you are actually using.

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Answer 3

BorysJ Author

Level 1

8 points

Dec 30, 2020 12:10 PM in response to Grant Bennet-Alder

Thank you for all informations but I still don't understand why it worked for 1 year without any problems and all cables and converters are still working well on another laptops etc. but they are not working properly on my MacBook. setup hasn't changed just update was made.

To conclude everything I should buy better HDMI cables and converters right?

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Answer 4

Dec 30, 2020 12:15 PM in response to BorysJ

To check that that is the solution, I suggest you try setting a lower resolution, such as half as wide as you are currently using.

If the display works reliably at that lower resolution, then better cables is likely to make an improvement.

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Answer 5

BorysJ Author

Level 1

8 points

Dec 30, 2020 12:34 PM in response to Grant Bennet-Alder

one of two external monitors started working very good like it used to but it was also very random sometimes it turns on 10 min after turning on MacBook sometimes after 2 hours sometimes it is not lunching at all. I can't change resolution on the other monitor (which is the same) because MacBook act like its not plugged in. Resolution on the one that is working now is 1080p and it's working without any problems. If Im making lower resolution it will not turn on immediately after MacBook reboot but it might turn on randomly after few minutes or few hours.

When finally MacBook connects to monitor it works perfectly until I will shut it down.

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Answer 6

Dec 30, 2020 10:40 AM in response to BorysJ

what resolution are these displays?

EXACTLY what cables and adapters are you using to make the connections?

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External monitor - no signal

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