Hi Forum Experts, First THANKS to those who have been helping my son troubleshoot his Arduino. He's younger than you may have guessed, but well ahead of me in this realm, and the advice is really valuable.
As you may recall if you saw the thread from earlier today he was powering up a ArduMoto motor driver shield, attached to the Arduino, when the shield power trace fried. Apparently one (or both) of a pair of matching caps on the Arduino also got burned (one is obviously damaged). These are labeled C6 and C7 on the schematic. We have learned these were 22uf and should be 100uf , orange in color, and are ordering replacements which I can hopefully install. ( It looks like the board may be a Chinese made version or knock off -but otherwise seems to work fine.)
He was powering the Shield with a nominal 13.2v NiMh battery and thinks the polarity may have been backwards. QUESTION 1: can we confirm that bad polarity on the shield would cause the damage described?
QUESTION 2: He currently can not power the Arduino off the VIN pin (2.1mm barrel jack). It does power up fine thru the USB plug. Is this consistent with the above problem (damaged C6 and/or C7 caps) or is there something else going on?
QUESTION 3: He has also noticed that the 2 smds located between the barrel jack and the USB jack are getting quite hot when the board is powered over the USB. Is that normal, or perhaps also related to the one or more damaged caps?
We are hoping that we can replace the caps on the Arduino, jumper the burned trace on the ArduMoto board, and get him back to building his Roomba-based robot!
If you can offer any guidance (pls assume we are ignorant but learning fast) we would really be grateful.
Cheers, Andy & Tim