I ruined my Arduino Uno. Can it be fixed?

I have an Arduino Uno R3 (genuine Made in Italy version). I was using it on a moving vehicle that suddenly started moving too quickly, and the USB cord was pulled suddenly out of the Arduino. Now the Arduino doesn’t work.

If I plug the Arduino into my computer using a USB cord, it does not show up in my Device Manager (I’m running Windows 7). Nor does it show up on the Arduino software. The TX and RX lights glow steadily, and the L light glows about 1/3 brightness.

Any way to test or fix the Arduino? I looked for information on that, but couldn’t find any. Any hints on where to look or what to do would be appreciated.

UPDATE: I forgot to mention that the green ON light also comes on.

Just pulling the cord out is unlikely to have caused any problems. If the cord was pulled out and it twisted the socket then the circuit could be physically damaged or something could have shorted. I’d look for signs of physical damage around the connector, like a cracked track or joint which you might be able to solder. It is likely that the board is a write off, though.

They aren’t the most robust things. I have quite a few dead ones now, some genuine Italian, some Chinese.

Also have you tried a different USB lead? It is possible that was damaged in the incident.

Sounds like one or both of the data lines aren't connecting. You might be able to fix it by re-soldering or replacing the USB socket. Look around the socket for broken solder joints.

Thanks for the replies. The USB cord appears to work fine with my other Arduino, so it does seem to be the Arduino Uno that is damaged.

Looking more closely at it, as advised, I see no broken solder joints. But I do see a scorch mark on the USB port, and it looks like the reset button (right next to the USB port) is discolored. That may be proof of the problem. I'll try to get a picture of the scorched area to post.

I agree that this Uno is probably shot, but I guess I've got nothing to lose by trying to fix it but some time and the cost of a few parts. So I'll probably give it a go, unless others think I'm just beating my head against the wall.

UPDATE: I tried to get a picture of the possibly damaged area, but could not get one that looked helpful. I may try again later.

You can put a magnifying lens against the lens of a camera to allow it to focus at a closer distance.

The magnifying glass is a good idea, but I couldn't get any good pictures with it either.

Using the magnifying glass, though, it looks like there is a fuse or something between the USB port and the reset button. Whatever it is there, it's blown. I'm trying to find out what that is, but have not been able to find a layout picture that identifies it. If anyone knows, please let me know.

Here is the part that blew. That little surface mount part between the USB port and the reset button. Is that a resistor?

UPDATE: Near as I can tell from the schematic the part is a 500 mA fuse.

Here is a picture of my Arduino Uno with the blown part:

It is not a fuse but L1 - ferrite bead BLM21. Look at the Eagle files. Fuse is brown part with golden contacts below USB and next to transistor.
...and also C8 1uF looks shady onward down the smoked trace.

Thanks, Budvar10. That makes sense. I see now that it couldn't have been the fuse. I would not then have gotten power to the board.

A ferrite bead inductor blowing makes more sense. Though how I could have done that I don't know. It's a mystery. That ferrite bead really blew and like you say smoked the trace to the capacitor as well.

As you suggested I got the Eagle files for the Arduino Uno R3 and am trying to figure them out. There seems to be some problem with the Eagle files I got -- the components do not show on the board layout. (Or possibly I just don't know what I am doing enough to get them to show up.)

It looks like I may have damaged more than just the ferrite bead. The capacitor C8 may be damaged (as you say), and maybe the 16u2. If it's the 16u2, I won't be able to replace that. Beyond my skill level.

Maybe if I'm lucky the 16u2 just needs to be reprogrammed. Maybe I'll try that.

Thanks again for the help.

Hot air rework station is needed for ATmega16U2 replacement.

Good point. I don't have a hot air rework station, nor would I use it enough to justify buying one.

But I will try to rebuild the ground connections that got blown away, without trying to replace the ferrite bead for now, and see if I can get the 16u2 to work.

johnwasser:
Sounds like one or both of the data lines aren't connecting. You might be able to fix it by re-soldering or replacing the USB socket. Look around the socket for broken solder joints.

If the USB socket is bad, I would suggest buying a Seeed Proto-Shield from Radio Shack (part # 276 0244).

It's only $6.00 and it's a proto-shield bare PC board, a bunch of 0.025 header pins (long and short ones), lots of resistors and LED's, plus a few of those cheap "reset button" type push buttons, a nice 10K pot, several female "Arduino type" connectors, a few DPDT slide switches and.....getting to the punchline...... a USB socket that's identical to the one used on the Uno and Mega.

So, for $6.00 you get the part needed (no way to buy one from Ebay + shipping cheaper than that), plus you get a bunch of really handy parts and a proto-board as an extra bonus!

You can unsolder the reset sw to get at the L1, just replace L1 with a piece of wire to see if you have other issues.

Robert

Krupski:
If the USB socket is bad, I would suggest buying a Seeed Proto-Shield from Radio Shack (part # 276 0244).

I don't think the USB jack is bad, but I did take your suggestion and buy a proto shield at Radio Shack. It does have a lot of stuff I can use, and $6 is not a bad price at all.

I was surprised to see how much Arduino stuff Radio Shack has now. That will be handy for me, as long as they stay in business.

rcorr:
You can unsolder the reset sw to get at the L1, just replace L1 with a piece of wire to see if you have other issues.

Robert

Great idea. I'll probably remove the USB jack instead of the Reset switch, since it looks like some of the traces under the USB jack are damaged.

I may try conductive paint instead of a wire. Anyone used conductive paint to repair damaged PCB traces?