My Arduino Nano is on a stripboard which provides a convenient access to some pins. It is connected to two I2C devices. The power supply comes from the USB port. It worked yesterday.

Today I plugged it to one of the USB ports of my PC. The power LED lit up for a split second and then the LED went off. I could smell something had burnt. My USB ports are surge protected: if a device draws too much current the USB power supply should shut down.

I unplugged everything and tested in the following order:

  • All the USB ports of my computer work with other USB devices
  • The Arduino alone powers on
  • The Arduino can send serial data through USB
  • The Arduino powers on when connected to the stripboard
  • I can upload sketches to the Arduino
  • The Arduino can send data coming from the first I2C device through USB
  • The Arduino can send data coming from the second I2C device through USB
  • The Arduino can send data coming from both I2C devices at the same time through USB

The last test is exactly the same setup as when I experienced the issue. It now seems to work again. Visual inspection did not reveal any burnt component or tracks on the Arduino or the I2C devices. The smell seems to come from the Arduino.


  • Can there be a smell without any actual damage?
  • What might have been the problem?
  • What tests I should run to check for hidden issues?

First question here, thanks for reading :)


closed as off-topic by Chris Stratton, Rev1.0, awjlogan, Dmitry Grigoryev, Scott Seidman Sep 25 '18 at 14:50

  • This question does not appear to be about electronics design within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    \$\begingroup\$ It's hard to tell what's wrong without schematics and good pictures of your circuit. It may be a jumper that is touching another contact or maybe you're working over a metalic surface and that is shorting contacts in the bottom layer of your board. \$\endgroup\$ – Ricardo Jan 17 '14 at 0:48
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    \$\begingroup\$ As for the smell, you must have definitely hurt a device. It may continue to work for who knows how long, but you probably have shortened its life. In any case you've been much luckier than I have. I've burned three ATmega328P just like that! No fireworks, no smell. \$\endgroup\$ – Ricardo Jan 17 '14 at 0:52
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    \$\begingroup\$ Maybe you shorted +3V3 output to ground on your board. That forced high current through the onboard regulator that shut down. That could explain the behaviour you reported (power LED light up for a split second then going off). That wouldn't damage the MCU, only the regulator, which may continue to work or not. One thing to watch out for is when you connect a board like nano onto a breadboard in a way that the board hides the connections. In some cases you may connect pins in short without knowing, if you miss the right strip on the breadboard. That's how I lost one of my MCUs. \$\endgroup\$ – Ricardo Jan 17 '14 at 1:05
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    \$\begingroup\$ The short is gone. It either burned, opening a short. Or it was removed. I often have such encounters. Where either the Plastic of the Chip is heated or a wire trace and the solder mask is heated. Where they off gas. This makes you appreciate the need to have spares. As this may be problematic or just keep going. I personally like Ricardo's possibility of a short between the regulator and GND. The USB will constrain the supply to just before popping the linear regulator. \$\endgroup\$ – mpflaga Jan 17 '14 at 3:00
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    \$\begingroup\$ I'm voting to close this question as off-topic because it was unanswerable four years ago and it is still unanswerable today. \$\endgroup\$ – Chris Stratton Sep 24 '18 at 1:30

You probably hurt something. But keep using it until it dies. :-) Did you try to power it from a non-USB source? You could have done some damage to your voltage regulator.

I recently burned a trace on my board. It popped right out of the board, let out the magic smoke, and made me scared I had fried the whole thing. One bus wire soldered to the right place, and I'm back in business. Pictures of the issue and the fix are here. Good luck.

  • \$\begingroup\$ your link is now broken. \$\endgroup\$ – shredalert Sep 22 '18 at 20:58
  • \$\begingroup\$ @shredalert Updated. I let the domain expire, apparently. :-) \$\endgroup\$ – kmort Sep 23 '18 at 22:11
  • \$\begingroup\$ glad it's back up again! :) \$\endgroup\$ – shredalert Sep 25 '18 at 9:05

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