I was desperately testing different codes for my mobile robot, all of a sudden I hooked up the wires from my 7.4V @ 1Ah LiPo battery in the Vin and GND pins backwards and then my board crashed . I didn't look up at the wires polarity properly cause I had been doing that for days but s**** happens.
Fortunately I could use it again, powered it via USB cable, but given the circumstances I'll need an external power source. The thing is that I don't know what component has been damaged; thought it could be the voltage regulator, but if anyone could give me an advice on this, I'll truly appreciate it.
And even more if there is a way of fix it, even though it sounds pretty difficult.
If the board presently works using USB power but does not work using Vin power because of your reverse polarity 'brain fart', then the two likely components to change is the voltage regulator and the 47ufd cap on the input to the regulator.
See schematic, upper left section.
In the future you might consider wiring your external voltage source to a DC power plug and just connect it via the DC power connector on the board, that would have protected you from reverse polarity as it has a series polarity protection diode.
The voltage regulator should be at 3.3V or 5V? I already replaced for one at 3.3V. And its not working yet with my battery... I'll apreciate your response.
rodolf0:
The voltage regulator should be at 3.3V or 5V? I already replaced for one at 3.3V. And its not working yet with my battery... I'll apreciate your response.
Thanks
The 5V one, and it feeds the input to the 3.3v one, so the 3.3v one can't work if the 5v regulator is bad.
Like I told you in the last post I replaced the original NCP1117 voltage regulator for a generic one. I thought the problem was the output voltage that seemed to be at 3.3V but turns out there's a wide voltage range that works for.
The problem was that the one I replaced it for has a different pin configuration and that was the reason it didn't work at the first try.
Today I got a new voltage regulator with the same pin config than the original, replaced it and No, it's not working yet. =(
So I don't know whatelse can I do? I think I'm out of ideas.
What is the part number of the replacement part, what is the voltage at both it's input and output? does it still operate from the USB cable?...
IN OTHER WORDS, WHAT CHANGED? WE CAN'T READ MINDS AND MY CRYSTAL BALL IS BROKEN...
I've externally powered my aduino just using a standard 7805 regulator chip connected to +5v pin and ground. Not sure how this would play with the USB power source connected at the same time.
. I didn't look up at the wires polarity properly cause I had been doing that for days but s**** happens. 
