Bottom USB port failing


10 posts
by dan3008 » Mon Dec 17, 2012 8:03 pm
Hi guys

First off, I have an old 256mb board that's been running for a while now. I've not changed anything, and yesterday it was working fine, and today the bottom port has stopped working. it seems to be intermittently providing power to the device...

At first, I assumed it must be a broken contact, but after poking it with a volt meter, I can safely say i dont think it is.

Anyone got any ideas what it could be? I dont really want to have to go and order myself a new board :( I've grown quite sentimentally attached to this one :( (yes i'm a silly person who gets attached to computers)
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by redhawk » Mon Dec 17, 2012 8:08 pm
Anyone got any ideas what it could be?

Dry solder joint, broken track but not visible to the naked eye?? hard to say really.

If the top USB port is working then a solution to your problem would be to share the +ve and ground rails between both ports.

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by dan3008 » Mon Dec 17, 2012 8:18 pm
Is it worth attempting a return to farnell?

I've not misused my pi at all, and so havent broken the warranty agreement. However, I nolonger have the orrigional box or anti static wrap that it came in :/
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by abishur » Mon Dec 17, 2012 8:35 pm
You say an older 256MB Pi, how old are we talking here? Does it still have the fuses by the USB ports, or have they been replaced with the 0-ohm resistors? If it's the fuses, then there has been some documentation that they can permanently trip out on you (which is why they were removed in the end). I took my first pi and removed the fuses myself and soldered a bit of solid copper in its place giving me a permanent 0-ohm "resistor" ;) Sadly, I was too vigorous in removing the first fuse and tore off the contact pad thus I only have one working usb port, but it's all that I need.

Other people have left the fuse in place and simply soldered a 0 or 1-ohm resistor around the fuse thereby bypassing them in a much less damaging or permanent fashion.
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by redhawk » Mon Dec 17, 2012 8:44 pm
If you have polyfused USB ports then I would recommend you solder wired joints across each one that's how I fixed up my PI. :)

Image

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by dan3008 » Mon Dec 17, 2012 9:00 pm
I ordered back in august (21st, and it arrived for my bday on the 30th :D). I just meant old, as in compared to current pi's, (aka before the update to the 512mb model)

So I cant be sure if it has the polyfuse or resitor :/ as its right on the change point. But my Revision number in cpuinfo is 0003, so i think that means it was just after the polyfuse was removed. based on http://www.raspberrypi.org/archives/tag/polyfuses

Think its going to be a return to supplyer job :/

Didnt want to be without my pi over christmas, but there we go.

Not checked if the resistor has blown though, I'll poke that with the volt meter next.
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by dan3008 » Mon Dec 17, 2012 10:01 pm
Right, I've sent an email to farnell to see if this failure is likely to be covered on warranty, If not, then I'm going to try bridging the power supply for both ports, and failing that, I'm going to just use my remaining port to attach a powered usb hub lol
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by abishur » Mon Dec 17, 2012 10:04 pm
You can easily confirm if you have a fuse or resistors by looking at them and seeing if a 0 is printed on them. If it says 0 then they're the resistors and you bridging over them won't fix anything.
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by dan3008 » Tue Dec 18, 2012 12:10 am
Yep, just looked, they are resistors.

I'll get it sorted. I needed a new pi anyway lol
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by dan3008 » Sat Dec 22, 2012 10:13 pm
Just wanted to let people know, I've fixed it. It was one of the spring clip bits on the bottem had worked lose.

Fixed now. Thanks for the help :)
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