user76329: While working on my project I supplied 12v to my pro mini through raw input and then a s4 named component smoked and my pro mini  stopped working . It didn't turn on either through vcc or raw. The voltage regulator seems completely fine. Can I repair my pro mini. Please help. 

user316: Many Arduinos have a Schottky diode between the power connector and the voltage regulator as a protection against accidental reverse polarity connection. The official Pro Mini, or the Sparkfun variant, does not.
So you can either de-solder the diode or break it off the board using diagonal cutters and then replace it with either a similar diode -- or with a solder-bridge if you are confident about never connecting power the wrong way around.
It's possible (likely even) that other components that look OK visually are actually damaged. Especially if you can't power the board by connecting a regulated 5V supply to the VCC pin.

76329: <p>While working on my project I supplied 12v to my pro mini through raw input and then a s4 named component smoked and my pro mini  stopped working . It didn't turn on either through vcc or raw. The voltage regulator seems completely fine. Can I repair my pro mini. Please help. <a href="https://i.stack.imgur.com/fd3Kn.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fd3Kn.jpg" alt="enter image description here" /></a></p>
 316: <p>Many Arduinos have a Schottky diode between the power connector and the voltage regulator as a protection against accidental reverse polarity connection. The <a href="https://www.arduino.cc/en/uploads/Main/Arduino-Pro-Mini-schematic.pdf" rel="nofollow noreferrer">official Pro Mini</a>, or the <a href="https://www.sparkfun.com/datasheets/DevTools/Arduino/Arduino-Pro-Mini.pdf" rel="nofollow noreferrer">Sparkfun variant</a>, does not.</p>
<p>So you can either de-solder the diode or break it off the board using diagonal cutters and then replace it with either a similar diode -- or with a solder-bridge if you are confident about never connecting power the wrong way around.</p>
<p>It's possible (likely even) that other components that look OK visually are actually damaged. Especially if you can't power the board by connecting a regulated 5V supply to the VCC pin.</p>
