Eeeek please help! Arduino broke!

Hey everybody!

OK so I was working with my Arduino for my University major project, when, a 12v wire mistakenly touched the 3.3v leg of the thermometer that was attached to the Arduino! The Arduinos lights flashed, the LCD screen flashed, the 240v relay flashed....you get the picture! Anyways now the LCD won't turn on but has a faint light on it, the green ON LED on the Arduino is on, the TX and RX lights are faintly lit and a orange LED is on by an L.

So the sketch is no longer running and my laptop won't recognize the Arduino when plugged in. I have disconnected everything from it but the USB cable and still the same lights lit on the Arduino, PC won't connect to it and the sketch won't run!

Give it to me straight, is it dead or can it be fixed? :frowning:

Dead. Hard to repair without hot air rework station to remove/replace the USB/Serial adapter chip.
328P if a DIP can be pulled & replaced.
Both will need new parts & reprogramming.
Still have good 5V & 3.3V? Those regulators may not have fried.
The little FET that does auto power switching may been fried too.

Be more careful with your next board - don't have power applied when moving wires around.
That said, I have a couple of promini's waiting to have their 328Ps replaced from doing the same thing 8)

:~ god'am it! Really gutted! I am guessing it wouldn't make a difference if I was to say that it wasn't connected to the serial cable/laptop when it happened? I was connected to an external 12v power source instead.

Anyways it sounds dead forever so that sucks but you learn from these things. How does it break the serial port then? Or is it not east to explain?

Thanks!

You had 12V flowing thru the uC pins, which are interconnected to other pins internally, and thus to the Rx & Tx pins and the Vcc pin on the USB adapter. Neither part is rated for 12V, 6V being absolute max. As noted, you are not the first to fry something. I blew holes on the tops of a couple parts in college with incorrect supply voltage, hole in the cover over the chip. Made a nice bang.

I try and make my designs more modular now so that the uC and the USB/Serial can be indepently replaced if needed - the space on the right is for an FTDI module, or an off-board FTDI Basic or similar can be connected for download/debug and then removed if fulltime PC conectivity is not needed.

Ah yea I get that now. I know lots of people blow things up, and my time had to come at some point, just wanted to know how/what blow but I know now so thanks! And good design there on your part! :slight_smile:

Thanks. Just one of many, and many others not posted ...
http://www.crossroadsfencing.com/BobuinoRev17/