lmv358 is U5A on the schematic.http://arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdfThat is the same IC and function as on a Mega IC7. http://arduino.cc/en/uploads/Main/arduino-mega2560_R3-schematic.pdfThere seems to be a rash of those unlucky users. Here is another with the same problemhttp://arduino.cc/forum/index.php/topic,135704.0.html
Certainly possible a 'bad batch' of the op amps got into a arduino production run? I had never heard of this symptom reported here before in the years I've been here.
QuoteCertainly possible a 'bad batch' of the op amps got into a arduino production run? I had never heard of this symptom reported here before in the years I've been here.If it were a bad batch of lmv358's, I think you would be correct, it would be more prevalent, which it isn't. It appears to be limited to two conditions in common:1) usb and Vin poweredThat is not and has never been a problem with the arduino auto-voltage selector circuit. It was designed to be powered from either or both sources attached, that is not the root cause of the problem, there has to be some component failure problem either from manufacture or user caused.2) Vin > 11vAgain that is well within the board's operating limits and specifications and has never been a problem in the past.It's an interesting symptom/failure and so far we have not yet determined if there is a common cause to these two reported 'hot op amp' symptom reports or not. A common symptom does not necessarily mean a common cause, further troubleshooting would need to be performed to determine if that is the case or not. Lefty