Pegasus2 R4 Mounting Issues on MacOS 15.2

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Ben Broad posted this 08 January 2025

I have a Pegasus2 R4 unit.

It works on my 2018 Macbook Pro, but not on my 2024 Macbook Air (M3, MacOS 15.2). 

I am connecting it via a Thunderbolt 2 to Thunderbolt (USB type C) connector. 

I followed the instructions published at https://kb.promise.com/thread/installing-the-macos-pegasus-dext-driver/ 

I ran systemextensionsctl list | grep pegasus which returned [activated enabled]

The drive mounts briefly and I can see the files. It unmounts after about 20 seconds.

While troubleshooting I noticed the Thunderbolt cable was very hot at the drive unit end. The drives remained lit up (blue) after the cable was disconnected and remained so until I removed power.

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R P posted this 08 January 2025

Hi Ben,

The usual suspects in cases like this are...

  • A bad or intermittant Thunderbolt cable.
  • The power supply is going bad.

The cable is easy to test, try another cable.

The power supply is a bit more difficult. One test is to power down the Pegasus, remove the power cable, then unseat all the drives, pull them out maybe 1/2 inch leaving them in the same slot, then plug the power cable back in and see if the Pegasus will power up and stay powered up without the drives. If it does then the power supply is getting weak. Shut the Pegasus down and remove the power cable and re-insert the drives. Then plug the power cable in and boot it again. Sometimes after this test things work OK, so it's worth a try.

Note: Be sure that the Pegasus is powered down and the power cable removed before unseating or reseating the drives.

Ben Broad posted this 22 January 2025

Thanks RP.

I followed your suggestions and found, with drives removed, the Thunderbolt light would flash intermittently, and on occasion the blue light would change to red. This would also happen when the cable was plugged into the other port on the Pegasus. I am seeking a new Thunderbolt 2 cable to test.

Ben Broad posted this 10 February 2025

The unit no longer turns on. I had a look at the power supply (FSP250-50LC) and did a search for a replacement. There seems to be a number of them with different wiring/connectors. Is there an exact part number for a replacement unit?

Thanks.

R P posted this 12 February 2025

Hi Ben,

Sorry, we have no information on the power supply.

Over the years other forum posters have found replacement power supplies and posted of their success, but I don't recall that anyone posted where they found it and what the part number was.

Another solution is to find a used Pegasus chassis. You can try EBay, Amazon, google shopping and even a local computer store.

Currently the Promise Shop has some refurbished Pegasus R4's for sale. This would work.

Jake Norton posted this 6 days ago

Hi Ben, Did you ever figure out a replacement power supply? I've been looking as mine for my Pegasus32 R4 just died as well. Would love to hear what, if anything, you figured out. 

And, Promise, it might be wise to either (a) keep a stock of these to sell, or (b) have a part number and resource to find them online. I pulled mine, like Ben, and it is a unique wiring configuration you have which makes it quite difficult to replace. And, seems that it is not uncommon for these power supplies to go bad. 

Jake Norton posted this 5 days ago

If anyone comes upon this post and is looking for a new power supply for their Pegasus32 R4 unit, I found one yesterday from KDM Power out of Houston. The unit came today, took me 10 minutes to install it, and my R4 is now back up and running. 

Here is a link to the unit; I found the people at KDM to be very knowledgable, responsive, and helpful:

https://www.ebay.com/itm/336158204663

Ben Broad posted this 4 days ago

Hi Jake,

I found a unit on ebay (https://www.ebay.com.au/itm/152603942091). 

It worked.

Funny story though: I still had problems with data transfer so I went looking for a new Thunderbolt 2 cable. Couldn't find one from a reputable source at a reasonable price, so I settled on a new Apple converter cable. That worked, but then one of the drives failed (insert eye roll). 

My R4 is too old to be worth further investment. A new unit is quite expensive and my justification for getting it has changed so I got a 6TB portable drive instead.

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