Released on October 23, 2012. Core i5 or Core i7 Processor. Apple Fusion Drive.

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The USB ports stopped working

Mac mini Late 2012 - 2.3 ghz Core i7 , - The USB ports (all4) stopped working - after I plugged all the usb devices: scanner printers hard disks -around 10-11 devices- and they were all turned on and connected to the computer via self powered usb hub, and when I started the computer I had a (USB device drawing too much power) error message , and all the usb went down , I researched and did all the suggested solutions I tried resetting NVRAM/ PRAM , and SMC. with no result, I ran the Apple Hardware (Extending) Test and the result was surprisingly “No trouble found” pass number 1 .. I re-ran the test again pass number 2 got the same result “No trouble found” yet still the usb problem exist. could it be a hardware malfunction, if so is it possible to replace the USB ports or hub or its controller only from the logic board instead of replacing the whole board?, n.b.: everything else is working fine (firewire, thunderbolt, ethernet, bluetooth, wi-fi, earphone … etc)

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With a powered USB hub are your devices accessible that way? Basically, did the power service within your Mac Mini fail or is the USB hub chip?

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hi Dan, thank you for your reply,

No, With a powered USB hub the devices are not accessible, and for the general power service within my Mac Mini, it is working fine, it is only the 4 usb ports that are completely dead. (when I mentioned the external hub was because I think that caused the problem .. when I started the computer while around 11 devices was connected to it and they were all on)

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The Mac mini's USB ports have two functions, the USB signal and power for devices like a mouse.

As you state the powered Hub is not able to access the USB signal side of the connection back to the Mac Mini this implies the USB hub chip inside the Mac Mini is damaged.

Using the powered hub (powered) allow us to make sure the power side of the Mac Mini's USB ports wheren't the issue as the power from the independent power supply would feed the devices connected to the hub (not any of the mini's USB ports).

You could also use a USB tester like this one: USB Charger Doctor Current Voltage Charging Detector Battery Voltmeter Ammeter to test the USB power service from the Mac Mini.

Sadly, at this point I think your logic board is damaged.

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hi Dan, thank you for your answer,

I’ll get the USB tester soon and do the test, my other concern is if the logic board is damaged (as you expected, and me too).

Is it possible to solder a replacement chip or controller (ie.,with electronic solderer specialist) instead of get a new logic board? Otherwise I think my best and last solution is to buy a thunderbolt 2 dock

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Sure its possible for someone with the needed skills & tools to fix your logic board Vs replacing it.

I would recommend you make sure your power units are correctly matched with the different devices like HD's some use higher voltages which can damage your system (and the device) if used on the wrong device. I would also make sure you have all of the AC plugs plugged into a good surge suppressor or UPS so a power surge won't get though.

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hi Dan, thank you very much for your concern,

I am indeed using a ups with a suitable power for all the devices and everything was working normal for years (with the same devices) I just had to move to a different apartment, this is when I plugged all the usb devices to the computer while the computer was turned off (but the devices was all turned on), and when I started the computer, I had the error message (USB device drawing too much power), and since then all the usb went down.

ps. I just ordered the USB tester and it will be delivered within the next 8 days. thank you again for your help.

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Now for the logic board (you gave me hope to proceed in this direction), Is there a way for me to determine which chip or part or controller on the board that need to be replaced?.

Also I had a comment on (Apple Hardware Test) , shouldn’t it detect the usb problem? ( because when I ran it it gave me (No trouble found).

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To be clear its the mis-match of the AC transformer for the given device that likely killed your system. Make sure they are matched correctly.

As for the repairing... Not so simple to answer as their are still quite a few parts one would need to test out and trace out in the schematics. This is beyond a typical DIY person.

As for AHT... I like the term 'Horizon' to describe this. Just like you can't see over the horizon AHT has its limits!

The horizon for it is the digital side of the system (inner-world) once you get to the outer interface side of the circuit (outer-world) it can't test these things without a loopback tool. Over the years the loopback tool was dropped as it was no different that a known good device or using a USB test tool I pointed you to if the power side of the connection was in question.

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