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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.

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Chosen Solution

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.

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

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@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.

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@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.

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@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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