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User profile for user: LotekJones
LotekJones Author
User level: Level 1
8 points

Troubles with three monitors connected

Hello Everyone,


Sorry for the length so here's the TLDR. Any assistance would be greatly appreciated, it's got me stumped!


TLDR: Can't connect three monitors at one time. Screens go blank intermittently and then display reappears and disappears again. The USB-C to HDMI converter appears to be the culprit but works fine when plugged into my work laptop (HP)


The issue:

I can connect Monitor 1 and Monitor 2 (see below for Monitor details) simultaneously just fine. When I connect Monitor 3, all three monitors will go periodically blank & the displays will return for a couple of seconds and then go blank again. It is similar to when the graphics card/processor is calibrating resolution.

I have determined that monitor 3 is the cause as when I only have this monitor plugged in the issue remains. (See troubleshooting below).


System:

Mac Mini (2018):

OS: macOS Catalona Ver 10.15.4

Processor: 3GHz Intel Core i5

Ram: 8GB

Storage: 500 GB SSD

Graphics: internal UHD Graphics 630 (1536 MB)


Current Monitor Configuration

Monitor 1 (main) : Acer S230HL (1920 x 1080) - connected using USB - C to DVI.

Monitor 2 (left side) : Phillips - PHL 216V6 Display - connected via HDMI

Monitor 3 (right side) Philips - PHL 216V6 Display - connected using USB - C to HDMI

The Acer has DVI and VGA inputs, the Philips has HDMI and VGA only.


Troubleshooting

  • Monitor 1 , 2 & 3 all connected - creates the issue
  • Monitor 1 & 2 connected - No issue
  • Monitor 2 & 3 connected - creates the issue


Using the HDMI cable with Monitor 3 connected using USB - C to HDMI & Monitor 1 connected using USB - C to DVI - No issue.

Using the HDMI cable with Monitor 2 connected using HDMI cable & Monitor 1 connected using USB - C to DVI - No issue.

Using either Monitor 1or Monitor 2 connected using USB - C to HDMI creates the issue.


So the conclusion is that the issue is with the USB - C to HDMI converter right?


Unfortunately I tested this converter on a HP laptop and there were zero issues in connecting.


I have recorded event logs if anyone is interested, it's got me completely stumped :(


Thanks!

Posted on Apr 30, 2020 12:59 AM

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,059 points

Posted on Apr 30, 2020 1:56 AM

You didn't say which Thunderbolt 3 ports you were using. The 2018 Mac mini has 4 Thunderbolt 3 ports but only two Thunderbolt busses inside. Ports 1 & 2 are on one bus, 3 & 4 on the other. Make sure you have only one display per bus.

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User profile for user: LotekJones
LotekJones Author
User level: Level 1
8 points

May 1, 2020 12:08 PM in response to Malcolm J. Rayfield

Thanks Malcom,


I moved the two thunderbolt connected displays with one each separate bus but still had the same result. The two monitors were $108 AUD each, so I guess you get what you pay for!


In the end I opted for a far more crude work around by Airplaying the third display using an old Apple TV unit I had lying around.


It's part of a Logic X setup, so the third display is to display the mixing desk so latency isn't a huge requirement as I use an ipad pro to physically mix. Although I was pleasantly surprised that the delay on the third monitor wasn't nearly as bad as I thought it would be.


Thanks again for your help.


I really appreciate it.


Luke

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Troubles with three monitors connected

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