Resolved [Help] Is my USB port dead on Mac Pro 5,1? [Resolved-ish With Workaround]

[xxVOXxx]

Looking to see if anyone has experience with diagnosing an issue with the built in USB 2.0 ports on the rear of the MP5,1. Of the 5 USB 2.0's, the two front facing work perfectly and when tested with a USB tester read 5.08 volts. Of the 3 rear ports, the two outside ports work well but the center one has suddenly not been connecting to devices so I tried the meter and it just flashes on and off 3.00 volts but does not stay on consistantly so it is getting little bursts of juice but not enough to connect or power anything.

This machine was purchased brand new in 2012 and has been babied its entire existance. All the USB ports are still very snug and the rear ones do not get plugged/unplugged often at all it stays static 90% of the time unless everything gets pulled for a hardware upgrade inside or cleaning.

-I have already tried the suggestion of resetting the NVRAM/PRAM with CMD+OPT+P+R and let it chime at least 3 times. This cleared up a small display issue with my Sapphire 7950 incidently but did not fix the single troublesome USB port.

-I also tried resetting the SMC by unplugging the power cable for 5 minutes, then plugging back in and restarting - and the other method I saw which was unplug the power cable then hold down the power button for at least 5 seconds, then plug back in and startup. This did not solve the issue either.

-The port has been cleaned out with air duster just in case, no change.

Hoping that there is a solution to this that I haven't seen yet to bring this port back to life, as the onboard USB 2.0 ports are the only ones you can reliably do things with like Keyboard, Mouse, and MIDI devices, or boot from a USB drive so my extra Sonnet USB 3.0 PCI Card slots can't take its place.

If I can avoid having to replace the board (backplane?) that would be great. Thank you to anyone who has any suggestions toward resolving this!

 

[mattspace]

Hoping that there is a solution to this that I haven't seen yet to bring this port back to life, as the onboard USB 2.0 ports are the only ones you can reliably do things with like Keyboard, Mouse, and MIDI devices, or boot from a USB drive so my extra Sonnet USB 3.0 PCI Card slots can't take its place.

My first test would be removing the Sonnet USB card to eliminate that variable. Do you have a spare power supply?

 

[xxVOXxx]

My first test would be removing the Sonnet USB card to eliminate that variable. Do you have a spare power supply?

thanks for the reply, Matt. I don't have a spare power supply but I just tried removing the Sonnet USB 3.0 card as you suggested and it did not fix the port. Also did another 3 chime NVRAM reset and SMC reset just in case with the Sonnet card out but no luck there. Attached is a video of what it looks like when I test all 3 rear USB 2.0 ports with the voltage meter.

Is there a fuse on the ports maybe needs to be replaced or reset in case there was a surge due to power out or hot plugging a device?

 

[tsialex]

Is there a fuse on the ports maybe needs to be replaced or reset in case there was a surge due to power out or hot plugging a device?

Yes, there are surface mount overcurrent protection fuses, one for each port, but if you don't have a hot air station, flux and are capable of replacing it, you gonna have to replace the whole backplane.

The SMD fuse is something like this mini PTC fuse:

Btw, the fuses Apple used on the MacPro5,1 USB ports are auto resetable, but after too much overcurrent usage over the years, it becomes permantely damaged.

When the fuses still work is just a matter of keeping the Mac Pro PSU disconnected from the mains and obviously no USB devices connected (remember that powered USB devices like a external 3,5" HDD or Cinema display need to be disconnected) for a day and the fuse restores itself.

If I can avoid having to replace the board (backplane?) that would be great. Thank you to anyone who has any suggestions toward resolving this!

Since you have two of the three back USB ports still working, get a powered USB 2.0 or 3.0 hub and connect your USB HID devices to it, won't be an issue for the keyboard and mouse which are usually USB 1.1 anyway.

 

[xxVOXxx]

Yes, there are surface mount overcurrent protection fuses, one for each port, but if you don't have a hot air station, flux and are capable of replacing it, you gonna have to replace the whole backplane.

The SMD fuse is something like this mini PTC fuse:

Btw, the fuses Apple used on the MacPro5,1 USB ports are auto resetable, but after too much overcurrent usage over the years, it becomes permantely damaged.

When the fuses still work is just a matter of keeping the Mac Pro PSU disconnected from the mains and obviously no USB devices connected (remember that powered USB devices like a external 3,5" HDD or Cinema display need to be disconnected) for a day and the fuse restores itself.



Since you have two of the three back USB ports still working, get a powered USB 2.0 or 3.0 hub and connect your USB HID devices to it, won't be an issue for the keyboard and mouse which are usually USB 1.1 anyway.

Thanks for the reply, Alex. I went ahead and disconnected the power cable and all other attached devices to the 5,1 and let it sit off for 36 hours just to be sure. Unfortunately when I booted it up just now and tested the USB port it still is having the same issue on just the one port. Just to make sure I did it right, do I have to actually go into the machine and disconnect the PSU wiring or was unplugging the AC cable and all devices from the outside sufficient to test the function of the resettable fuses? Also is there official documentation about this somewhere, this is a really interesting feature of the 5,1 I'd like to read more about how it works.

 

[tsialex]

… was unplugging the AC cable and all devices from the outside sufficient to test the function of the resettable fuses?

You need to remove any possible way that the fuse recieves power for it to reform, so disconnect the mains and any devices.

Also is there official documentation about this somewhere,

Not from Apple.

this is a really interesting feature of the 5,1

Not just the MacPro5,1, but probably any modern Mac that you can think of.

I'd like to read more about how it works.

You can read an overview of how the PPTC fuses work here:

A Comprehensive Guide to Resettable Fuses

Discover the essentials of resettable fuses in our comprehensive guide. Learn how these protective devices work, their applications in electronics, and key factors to consider when selecting the right type for your projects. Enhance your design knowledge and ensure safety with resettable fuses!

community.element14.com

 

[xxVOXxx]

You need to remove any possible way that the fuse recieves power for it to reform, so disconnect the mains and any devices.



Not from Apple.



Not just the MacPro5,1, but probably any modern Mac that you can think of.



You can read an overview of how the PPTC fuses work here:

A Comprehensive Guide to Resettable Fuses

Discover the essentials of resettable fuses in our comprehensive guide. Learn how these protective devices work, their applications in electronics, and key factors to consider when selecting the right type for your projects. Enhance your design knowledge and ensure safety with resettable fuses!

community.element14.com

Thanks for the link to that info. For clarification, when you say disconnect the mains what does that mean exactly? Is that just unplugging the AC power cable or something else?

 

[xxVOXxx]

Disconnect everything.

Yes, but do you mean all cables from the outside of the 5,1 only or do I actually have to also go inside and disconnect anything in the computer?

 

[tsialex]

Yes, but do you mean all cables from the outside of the 5,1 only or do I actually have to also go inside and disconnect anything in the computer?

Outside. Disconnect the PSU to mains, disconnect any USB devices and anything less obvious that can keep feeding power to the Mac Pro, like a powered FW drive/interface.

PPTC devices are not magical devices that can reform infinitely, after so much episodes of overcurrent/cycles of reset/reform, it just dies.

 

[xxVOXxx]

Since you have two of the three back USB ports still working, get a powered USB 2.0 or 3.0 hub and connect your USB HID devices to it, won't be an issue for the keyboard and mouse which are usually USB 1.1 anyway.

update: I have an Apple LED Cinema Display 27" which connects via one mini displayport plug and one USB 2.0 plug - this has a built in powered 3x USB 2.0 hub in the back of the screen. I tried switching ports for my monitor from one of the good ones to the bad one and you were correct, using a powered hub plugged into the bad USB port is allowing me to still use all the monitor hub ports, and it frees up one of the good USB ports in the back of the 5,1 for something else that requires power. Good to know the port still technically works, I can deal with this instead of replacing the backplane so this workaround kind of solves the issue. Thanks again!