Thunderbolt to USB Mac

  • Last Post 05 February 2021
  • Topic Is Solved
Rob Thompson posted this 04 February 2021

I have the Pegasus3 with the Thunderbolt 3 ports.

I’ve been using it for about a year connected to a Mac mini with the thunderbolt 3 cable.


Recently the Mac mini died and won’t start up at all.

I want to be able to connect the Pegasus3 to an older Mac with USB port.

I have purchased the Apple brand cable adapter “Thunderbolt 3 to USB”.

I hooked it up to the USB Mac but I get no response from the Promise unit.


The Mac is running 10.13.6 High Sierra.


Is it possible to make this work?





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R P posted this 04 February 2021

Hi Rob,

The Pegasus3 is a Thunderbolt only device and it won't work if connected to a USB port.

Rob Thompson posted this 04 February 2021

Thanks for the reply.

Before I posted this question i looked through the forum and support pages.

I saw refrences to the Thunderbolt3 to USB adapter and

USB driver downloads. I thought that may mean there would be a chance that I could make it work.

Did I compleatly misunderstand?



R P posted this 04 February 2021

Hi Rob,

As far as I know, there no such thing as Thunderbolt3 to USB, they are completely different protocols. A lot of the newer computers have USB-C ports that will do both Thubderbolt3 and USB3.1. That is, they support both protocols, and many vendors sell adapters connect USB3 cables to the USB3.1 ports.

Exacly which adapter do you have?

There may be some confusion because Thunderbol3 and USB3.1 use the same cable connectors. So you can physically connect a USB3.1 device to a Thunderbolt3 port, but it will not work. It also won't work if you connect a TB3 device to a USB3.1 port.

As for the USB filter drivers, they are for the Pegasus32, which supports USB. But Pegasus1, 2, and 3 still don't support USB.

If you have an older MAC that has a Thunderbolt2 port, I would think the Apple Thunderbolt3 to Thunderbolt2 adapter would be what  you need.

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  • Rob Thompson
Rob Thompson posted this 05 February 2021

This is the adapter that I have.

Apple MJ1M2AM/A USB-C to USB Adapter

Thank you for explaining this to me. I think I understand the problem much more clearly now.

I'm going to just buy a new MacMini and get this thing back up. The users are going to loose it on me if I make them use the cloud backup for their files much longer.

Thanks again for your time.