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weird: USB 2.0 devices not recognized, but USB 3.0 devices work ok

I've got a MacBook Pro 15" Unibody (Mid 2012) that's exhibiting a strange problem. The customer reports that the USB ports stopped working a while back; i.e.: the computer would no longer recognize any of his USB devices. They are all USB 2.0 devices (external drive, MIDI controller, etc.).

I did some testing and confirmed that it does indeed not recognize any USB 2.0 devices. Here's the weird part: the computer works just fine with any USB 3.0 devices that I've tested it with.

I've already tried all the usual quick fixes: reset SMC, reset PRAM, etc.

Of course, the next logical assumption would be that it's a hardware fault (i.e.: logic board). Is it possible for a failed component on the USB bus to knock out USB 2.0 functionality, while still allowing USB 3.0 devices to function normally?

Any advice will be much appreciated.

Answered! View the answer I have this problem too

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3 Answers

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You may want to get a USB tester tool like this one: Kitbon USB Multifunction Tester w/Overcurrent / Overvoltage Protection as well as this tool: Mercury T2C Protocol Analyzer If you are serious about testing USB port issues.

I suspect your real issue here is the ports fuse links burnt as the user used the wrong (or bad) power adapter for a device so it killed the port. A lighting strike can also burn the UART stage (part of the PCH).

I would start off checking the ports power using the first tool. Then consider shipping the logic board out for repairs or replace it.

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Thanks, Dan. All good info.

From what you're saying, it sounds like a component-level fault on the logic board. So I'm just going to bite the bullet and send the board out for repair.


@danj you know the ports on that machine ARE USB 3?


@mayer - For sure!

Both USB-2 & USB-3 use USB-A connector and the voltage/current checker I've pointed out here work for both. The Protocol analyzer works across USB-2, USB-3 (USB-A) & USB-3.1 (USB-C) its just a matter of the test lead you use. The link I posted doesn't get to the discreet tester you need to click on it on the left 'Mercury T2C Protocol Analyzer' or you could go with the older unit.


@danj the 'Mercury T2C Protocol Analyzer' is a little pricey for me :-( @ $1495. I did order the Kitbon.

I was surprised to see the 2012 with the USB ports listed as USB 3 instead of 2 when I found it.


@mayer - The first versions of USB3 ports had a blue insulator. Apple changed it back to a black insulator. So only the markings give you a clue or you need to open the hardware profiler to see it there.

Yes, the protocol analyzer is pricy! We rented one when we had some issues with a HP plotter to prove to HP the software driver was not working correctly.


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Did you find a solution to this problem? I have the exact same problem on my laptop for over a year now and it’s quite annoying

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@johnnyzero what was the issue with the USB ports in the end? I am experiencing the same issue on a mid-2012 MacBookPro9,1 - the USB 3.0 devices get recognized, yet the USB 2.0 devices do not. This happened after the topcase and the palm-rest was changed a few years back.

Thank you!


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