Displayport connected monitor - No signal - after wake from sleep

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Level 1

32 points

Displayport connected monitor - No signal - after wake from sleep

10.15.7, MacBook Pro 16" 2019, CalDigit TS3 Plus (firmware 44.1).

MBP <--> Power <-> TS3 Plus <-> DisplayPort cable <-> LG Monitor

Frequently, my DisplayPort attached LG 27UK650_600 monitor will not wake from sleep.

The monitor give the following warning: "No Signal. Entering the power saving mode shortly." The monitor attempts to find the signal from the MBP for ~ 27-28 seconds, and then displays the "No Signal. Entering the power saving mode shortly." again.

The displaypolicyd.3:0:0.log is filled with these messages:

displaypolicyd.3:0:0.log

If I remove the DP cable from the CalDigit dock and plug it into a thunderbolt port (with a known good DP<-> TB3 adapter), the monitor doesn't display the "No Signal. Entering power saving mode shortly." message at all. It just sits there - black as night.

Interestingly, if I remove power from the MBP, the monitor suddenly wakes up and all is well.

So, two questions:

1) Anyone seeing this issue?

2) Anyone know what those messages in displaypolicyd log indicate?

(Hint: If I shutdown and restart the MBP, everyone's happy...always).

P.S. Fans are spinning like crazy (5200-5600rpm) during this time.

MacBook Pro 16″, macOS 10.15

Posted on Sep 27, 2020 11:49 PM

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Answer 1

Oct 4, 2020 2:23 PM in response to o__b

Hi there o__b,

We understand you're experiencing an issue with your MacBook Pro and display not waking from sleep as expected, and we'd like to share a resource that can help.

Check it out here: If your Mac doesn't sleep or wake when expected

Specifically, take a look at the "If your Mac doesn't wake when you expect" and "If the previous steps don't work" sections.

We hope this helps.

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Answer 2

Sharhari

Level 5

6,293 points

Oct 5, 2020 6:16 AM in response to o__b

LG Monitor <-> DisplayPort cable <-> TS3 Plus <--> MBP <-> Power charger

Test connecting your power adapter to right side usb-c port and the TS3 Plus(dock) left side usb-c port.

Hope it helps.

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Answer 3

o__b Author

Level 1

32 points

Oct 5, 2020 9:13 PM in response to Sharhari

I wish it helped, but it did not. I'm really curious as to what the log information means. I think this has the answer to the issue. Unfortunately, I can't find anything on the interwebs. Oh well....

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Answer 4

o__b Author

Level 1

32 points

Oct 5, 2020 5:18 AM in response to barberlives123

I appreciate the feedback, unfortunately, this is not beneficial to me. My MBP wakes just fine. The problem is with the external monitor.

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Displayport connected monitor - No signal - after wake from sleep

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