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Arduino not powering up through the Vin Pin : A simple fix

Brings back the Vin Pin

If you have ever seen some magic smoke hovering around your Arduino, I bet there was this involuntary movement that resulted in you snapping the power supply from the board right away! And then you might have quickly scanned the entire board to see if something was blown up. Perhaps, you also thought that the poor Vreg's efforts weren't valiant enough to regulate the voltage or maybe the culprit was some other electronic part or circuit.

While there are so many ways to destroy an Arduino, temporarily or permanently, this extremely simple tutorial will teach you how to apply a simple fix to an Arduino if you accidently short the Vin and the GND pins when the Arduino is powered through the Vin pin or DC power jack. This will result in destroying the blocking diode of the Arduino and you will also notice traces on the underside PCB missing or melted. This means that you can no longer power your arduino through the Vin pin.  ( something that happened to one of my Arduinos a few months ago ) : 

 

As you can see, the Vin pin has been disconnected from the circuit..

 

When I tried powering up the Arduino through the Vin pin , it would not turn on.

 

So here's my story on how it happened. To be honest, I had no idea if this would ever happen. It was during the build of this sumo robot, where the Arduino was resting directly on the tin chassis. ( There was paper underneath the board to function as an insulator but the pins soon enough  had made their way through the thin sheet of paper) . And then I powered the Arduino. End of story. :D

So why did this happen? The blocking diode in the Arduino, as I mentioned above, allows for the flow of electricity to pass in one direction only. Since there is no current limit protection on the Vin pin, a short circuit from the Vin to the GND pin effectively short circuits the DC power jack input and if the current produced is too much to handle for the blocking diode, it will be destroyed. The melting of PCB traces is due to the heat caused by this large current. (It's just like when a motor driver cannot handle the current draw by the motors.) This figure will make things clearer :


 

So, how do you fix this? If some of you are thinking of tossing this Arduino and getting a new one, hold your horses! While the blocking diode might need to be replaced ( luckily it didn't get affected in my case ), a simple jumper can be used to breathe life into your Arduino.


You'll need a small piece of wire to act as a jumper 

 

Then, you simply need to solder the jumper to bridge the broken circuit.

 

There you have it. Turn on your Arduino. This time, things will be different.

In some cases, it might be the voltage regulator that's behind this mischief. If you power up the Arduino the wrong way, a reverse voltage will destroy the voltage regulator ( unless there is some sort of reverse voltage protection ). In that case, you'll either need to replace the voltage regulator or build your own custom regulator board using Voltage Regulating ICs like 7805.

Thanks for passing by. If some errors have crept in, I will be glad if someone points them out. It's a really simple fix, but hopefully it helps someone getting started with Arduino. It might be a good idea to heavily tape or cover the underside of the Arduino next time!

Ashim

References : http://www.ruggedcircuits.com/10-ways-to-destroy-an-arduino