USB port voltages - checking for reversed motherboard connectors

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amenex
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Joined: 01/03/2015

While setting up a second Intel D865GLC motherboard in a generic (no brand name) desktop enclosure I was faced with ambiguous connectors for the front panel USB ports - I can plug them in facing either way, so I can't tell if I have interchanged the +5V and +12V supplied to the device plugged in to the port.

Does anyone sell a gizmo that plugs into the USB port and tells me whether it sees the right voltages ? I may have to make one ..

This question arises because I was "forced" to use the ThinkPenguin wireless adapter because of too many NAS devices hogging the ethernet receptacles on my router, and this motherboard's PS2 keyboard I/O isn't functioning; I am using an Apple USB keyboard now, leaving no trusted USB ports free.

Jodiendo
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Joined: 01/09/2013

Simple, Research it! and read the manual of your board. there is plenty of forums and web sites for that kind of headache. Buy your self a solid multimeter and test those pins away. Intel has already schematic printed for their boards inside their package, the whole purpose is to avoid headaches of voltage pin-cross connections.

Michał Masłowski

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I am a translator!

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Joined: 05/15/2010

USB has +5V, ground and two differential data pins. There is no +12V.
Wires are usually coloured, red for +5V, black for ground.

Reading the manual or using a multimeter should answer your question.
You might also trace to which pins the wires go.

amenex
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Joined: 01/03/2015

Both responses are correct:

I was imagining that +12V pin (Pins 1 & 2 on Intel's drawing of the MB connector !)

Those wire colors: Again, imagination played a role. The red wires of the two USB internal cables are indeed at the #1 and #2 pins now, even though the printing on the two cables' receptacles face opposite directions (outwards when correctly placed on the header).

I'm too unsteady to attempt measurements with one of my clunky multimeters.

Here are three links that I found useful this morning:
http://pinouts.ru/Slots/usb_pinout.shtml
http://www.hardwaresecrets.com/article/Installing-Frontal-USB-Ports/90
http://www.hardwaresecrets.com/article/Connecting-Two-PCs-Using-a-USB-USB-Cable/248

amenex
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Joined: 01/03/2015

Solved ! Both USB ports work fine ... I actually had them plugged in OK from the get-go, but was nervous about testing, for fear of letting that magic smoke escape once again.