HDMI Monitor Blinking on MBP 13" after 5.05.202 update

Thunderbolt TBT3-UDC3
1

Hi - I followed all the instructions here and updated the TBT3-UDC3 to 5.05.202, however I’m still getting some nasty blinking.

https://support.plugable.com/t/monitor-blinking-on-hdmi-port-of-tbt3-udc3-with-mbp-16/20299

MBP 13", 2016, 2 Thunderbolt 3 ports
Mac OS 11.6

Is this still a bug?

2

Hi @thekiefs,

Thanks for posting!

Let’s see if we can narrow down the root cause of this HDMI flickering. What if you temporarily connect the DisplayPort to HDMI adapter that came with the package to the DisplayPort output on the dock, and then swap over the HDMI connection to that adapter?

When the same HDMI monitor is now connected to the DisplayPort output on the dock, are you still seeing this blinking?

Thanks for giving us a chance to help!

Mitchell

3

Hi Mitchell. I tested this and there are no flicking problems when connected as you described.

4

Thanks for trying that, @thekiefs.

Just to make sure I understand the problem, is this HDMI monitor blinking occurring constantly, even after initial dock connection? Or is it only occurring when you wake from sleep (or some other trigger)?

Additionally, can you reproduce the same problems on both Thunderbolt 3 ports on the Mac?

Thank you!

Mitchell

5

Hi, yes. HDMI Monitor blinks are constant after initial dock connection. Sometimes it is higher in frequency (every second vs every 20 seconds), but this is hard to reproduce.

It happens on all ports on 2 different MBPs. One
macOS 11.6, MBP 13" 2016 Two Thunderbolt 3 Ports

and another
macOS 11.6, MBP 13" 2020 Four Thunderbolt 3 Ports

6

Here are two videos on the 2016 MBP (which is notably worse than the 2020, and also sometimes shows a green and other white noise screen).

https://tmpfiles.org/128793/img_2254.mov
https://tmpfiles.org/128794/img_2255.mov

I’m using two LG HDR 4k Displays. The HDMI monitor is in 2160x3840 orientation and the DisplayPort monitor is in 3840x2160 orientation. This worked fine a few months ago.

7

Thank you for the additional details and for taking the time to shoot those videos!

I’ve just tested our MBP 13" 2020 (Two Thunderbolt 3 Ports, macOS 11.6) and our TBT3-UDC3 and it does not exhibit this kind of HDMI flickering.

If you have not tried already, the next steps we’ll want to take are to perform a power-cycle of the unit to reset its internal hub and video chipset. To do this, please follow these steps:

  1. Disconnect all USB peripherals and displays connected to the dock
  2. Disconnect docking station from host machine, then disconnect the power adapter from power
  3. Leave unplugged for 1 minute for power to dissipate
  4. Connect docking station initially into power only
  5. Connect docking station to host machine, then connect USB peripherals and the displays, then test for functionality

Please let me know if that makes any difference!

Mitchell

8

Unfortunately I’m running into the same issue on both laptops.

9

Thanks for trying that power-cycle.

Can you please reach out to us at support@plugable.com with the following information?

  1. The Amazon Order ID associated with your dock
  2. The serial number located on the bottom of your dock

You may use the subject line of “Ticket #355903” to help us match up that ticket to this post.

Thank you!

Mitchell

10

As an update to this thread, the customer reached out to us directly where we proceeded with a warranty replacement.

Unfortunately, the replacement did not help. After continued troubleshooting and attempts to reproduce the HDMI flickering internally at Plugable, we were unable to provide a clear resolution.

We’ll be closing this post, but for any other Mac user who is experiencing similiar issues though the HDMI port of the TBT3-UDC3 dock, please contact us at support@plugable.com or open a new post. We would appreciate the chance to explore further.

Thank you!

Mitchell