Connecting a usbc external SSD to an iMac with Thunderbolt 2

MartinR wrote:

It won't work that way.

You are trying to connect a USB drive that has a USB-C connector to a Thunderbolt 3 adapter that also happens to have a USB-C connector. Although they both happen to use the same type of connector, USB ≠ Thunderbolt. The adapter does not convert USB to Thunderbolt.

Another issue is that the Thunderbolt 3-to-2 adapter does not transmit power from one side to another. You cannot use it to attach a bus-powered Thunderbolt 3 SSD directly to a Thunderbolt-2-equipped Mac.

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Other World Computing sells a "Thunderbolt 2 Dock Solution" that consists of an Apple Thunderbolt 3-to-2 adapter bundled with one of their Thunderbolt 3 docks. So I think

Old TB2 Mac -> TB 3-to-2 adapter -> wall-powered Thunderbolt 3 dock -> USB-C (USB) drive

could theoretically work. (You could ask them to be sure.).

I wouldn't recommend it just to connect a USB-C (USB) drive. A simple USB-A to USB-C adapter can provide the OP with speeds of "up to 5 Gbps". A USB-C port on a dock would probably offer USB speeds of at best "up to 10 Gbps" – but it could easily cost $200+ to get the dock and the TB 3-to-2 adapter.

It won't work that way.

You are trying to connect a USB drive that has a USB-C connector to a Thunderbolt 3 adapter that also happens to have a USB-C connector. Although they both happen to use the same type of connector, USB ≠ Thunderbolt. The adapter does not convert USB to Thunderbolt.

It is unfortunately and endlessly confusing that USB 3 devices & Thunderbolt 3 devices both use the same USB-C connector.

Further tech detail about the Thunderbolt 3 adapter is here -> About the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple Support

Please review what @MartinR wrote. Most people are using USB based external drives which require a USB-C to USB-A Adapter to work on older systems. You cannot use a USB based drive and connect it to Thunderbolt 2 since they use completely different protocols.

Check the documentation of your external drive to verify which protocol it actually supports. You may need to look at the technical data sheets to be certain since the product information on the vendor's page may be misleading or confusing. Also check what icon is shown next to the USB-C port on the external drive. If it shows a lightning bolt symbol, then that port supports the Thunderbolt protocol. If the symbol is a trident or mentions or has some sort of numbers for speed, then it is using the USB protocol. If there is no symbol next to the USB-C port on the external drive, then it is most likely a USB port.

USB-C is a connector designation....that is all. USB-C ports may support the USB protocol or the Thunderbolt protocol.....some USB-C ports may only support a power only connection. You must carefully read the product documentation to know exactly what each port & device actually supports. It can be difficult to figure it out if the ports are not actually labeled with the actual supported protocol. When in doubt, it will usually be the USB protocol. Thunderbolt devices usually cost a bit more and tend to be higher end products only available from a small number of respectable vendors.

HWTech wrote:

You cannot use a USB based drive and connect it to Thunderbolt 2 since they use completely different protocols.

You can use Thunderbolt to implement other interfaces, but it takes active circuitry, similar to that found in a PCIe card. (E.g., the 27" Apple Thunderbolt Display used its Thunderbolt link to a Mac to support downstream USB 2.0 and FireWire 800 ports.). In practice, for USB, this circuitry is found only inside of displays / hubs / docks.

With USB 2.0 or 3.0 to FireWire "conversion", any time that you see an "adapter" that claims to do that, run away. Far, far away. It won't work, and it might be connecting pins in a way that could damage your equipment.

You may need to look at the technical data sheets to be certain since the product information on the vendor's page may be misleading or confusing.

A lot of vendors who sell USB-C (DisplayPort) or USB-C (USB) products refer to Thunderbolt, even though their products don't use Thunderbolt at all. I believe that they are trying to reassure Mac users that the products will work with Macs. Or confused. Or both.

All Thunderbolt 3 and 4 ports, by definition, have USB-C connectors. In addition, all Mac Thunderbolt 3 and 4 host ports support USB, DisplayPort ALT Mode, and Thunderbolt ALT Mode. So Thunderbolt implies the other capabilities, the ones the third-party device actually uses.

With the Thunderbolt 3-to-2 adapter, that "rule of thumb" goes out the window …

It sounds like you're experiencing compatibility issues when trying to connect a USB-C external SSD to your iMac with Thunderbolt 2 ports using a Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter. Here are a few troubleshooting steps and considerations:

1. While Thunderbolt 3 ports are backward compatible with Thunderbolt 2 devices using an adapter, the reverse is not always true. Thunderbolt 2 ports may not be compatible with Thunderbolt 3 (USB-C) devices, even with an adapter. Ensure that the adapter you're using is specifically designed to work with Thunderbolt 2 ports.

2. Test the Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter with another Thunderbolt 2 device, if possible, to confirm whether the adapter is functioning correctly. If the adapter works with other Thunderbolt 2 devices but not with your SSD, it's possible that the SSD's USB-C interface is not compatible with Thunderbolt 2 ports.

3. Some USB-C SSDs are designed to work specifically with USB-C ports and may not be compatible with Thunderbolt 2 ports, even with an adapter. Check the SSD's specifications or contact the manufacturer to confirm compatibility with Thunderbolt 2 ports.

4. If the SSD is not compatible with Thunderbolt 2 ports, consider alternative solutions such as using a Thunderbolt 2-compatible external SSD or using a USB-A to USB-C cable to connect the SSD to a USB-A port on your iMac.

5. Open "System Information" on your iMac (located in the "Utilities" folder within the "Applications" folder) and navigate to the "Thunderbolt" section to see if the connected device is recognized. This can help determine if the issue lies with the adapter, SSD, or Thunderbolt ports.

If you're unable to resolve the issue with the current setup, you may need to explore alternative solutions or consider upgrading to a newer iMac model with Thunderbolt 3 or USB-C ports for improved compatibility with modern external storage devices.

Hi,

I think it might be a power issue, your external drive is Self powered or Bus powered, as far as I know, pole USB-C to Thunderbolt adapter doesn't support Bus powered devices.