TBT3-UDZ dock is power cycling every few seconds all of a sudden

I have been using my TBT3-UDZ dock for almost 3 years with no issues- Lenovo Carbon X1 10th Gen I7 connected to dock via Thunderbolt 3 cable, and connecting dual Samsung CF382 monitors connected via HDMI ports, Keychron K4 keyboard via USB-C, Creative Pebble speakers via USB-A. I’ve had this setup for many years with no issue, but today, my keyboard stopped working after initally being fine to put in my PIN so I had to put it on BT mode, one monitor lost connection but regained it after I disconnected and reconnected the HDMI, speakers were not recognized. I then rebooted the PC, but now it power cycles every few seconds. Please provide any suggestions to fix. Thanks.

Hello DruidofNYC,

Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you.

You mentioned having already rebooted the PC to see if that would help, but if you’ve not already done so I also recommend to reset power to the dock via the below steps:

Fully unplug the dock from all devices, power, and Thunderbolt 3 cable to the host computer. Wait about 30-60 seconds, then reconnect the power cable first, Thunderbolt 3 host cable next, and USB/all other devices last. Sometimes this can help if one of the components in the dock is in a bad state temporarily.

If the dock continues to reset continuously then it may indicate something has gone wrong with the dock itself or the dock power adapter. When it power cycles every few seconds do you notice that the blue power light turns off when this happens? Or the light stays on while the dock resets/disconnects from the system?

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry

Senior Engineer | Product Owner
Plugable Technologies

Thanks, Joshua. I had read another post and tried the method you mentioned. It showed the same behavior, and the light does go out when it power cycles- I also get a loud pop from my speakers each time that happens.

In any case I found the issue, the supplied Thunderbolt 3 cable is malfunctioning. I swapped it with my Caldigit cable from another computer, and it runs like it had previously. It looks like I need to get another cable but the dock is OK.

You’re most welcome, and thank you for the update!

I’m glad that you had another compatible cable available to test with, it’s quite interesting that the cable was causing this behavior, it’s rare for us to see Thunderbolt cables fail in such a way.

At this point since you’ve been able to narrow the issue down, we would be happy to send you a replacement cable under our warranty. To arrange the replacement cable, please feel free to email us directly at support@plugable.com and I can then request some information so that we can get it shipped out. If able, please mention ticket 421661 in the subject line!

Thanks again!

That’s helpful, thanks.

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