Electronics > Repair

Help repairing a fried Arduino

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PostaL:
So, I've managed to burn my Arduino :(. What I did was I accidentally drop a 12V line on the ground of Arduino. I don't understand where the circuit was closed, because technically I've shorted the 12V rail, but  maybe this it's not that important now.

So, what's the situation now? The board starts up and it's recognised by the PC. I've changed the ATmega328 with another one that I've burned the bootloader on it (with another board), and the blink sketch that I believe was put on the chip by default at bootloading is working fine on my board (I can see the L led blink). The problem comes when I try to upload a new sketch: it's giving me the same error as it would if I choose the wrong board type (I don't have the board with me right now, I'll post the error code when I get home).

Where should I start troubleshooting the board? Can anybody point me in the right direction?

Thank you!

Psi:
Was the 12V from a battery or other high current supply?

The usual result (from a ground short) is a burnt PCB track.
Look for a track that's a different color to the others.
If you find one give it a scrape with your fingernail and the pcb coating will usually break off easily and show charred copper underneath.

If you find a track like this figure out how much of the track is burnt and where it is ok on each side.
Then scrap to expose fresh copper at each end and solder a piece of wire to join it back together.

PostaL:
I will not necessarily call it high current, but it's capable of 1 amp. The contact was very brief (less than a second).

I forgot to mention that all the LEDs on the board went on for a split second upon contact, so the circuit was defiantly closed somewhere. Maybe some current was still in the caps? I don't know, I'm still a newbie to electronics, just started some moths ago ...

I'll try to give tracks a better look. Thanks!

helloworld922:
Haha, must be a common failure mode with these Arduinos (I've done it, and I know someone else who's done it, too).

Both of our boards had fried the electrolytic power caps (near the power jack connector). Try replacing one (or both) of them if they don't quite look right. The Arduino website has the schematics for the boards freely available so you can look up their values (mine were 100uF caps).

Psi:

--- Quote from: PostaL on January 08, 2013, 09:11:47 am ---I will not necessarily call it high current, but it's capable of 1 amp. The contact was very brief (less than a second).

--- End quote ---

If it can only supply 1A then i doubt <1 second of short would produce enough temp rise to melt a track.

Melted tracks normally happen when you short batteries and get 10A+

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