Just received my Mega board and when I plug in the USB cable nothing happens. None of the LEDs light up including the power LED. Pressing reset doesn't help either. I haven't connected anything to the board yet so that cannot be a source of problems at least...
So I did some measurements and found out that at the USB connectors 5v pin there's a healthy 5.25v. The board's 3v3 and 5v pins have 1.53v which is obviously too low. Vin shows even stranger reading, 1.08v.
Does this indicate that the board's power distribution is somehow faulty? Unfortunately I haven't got an external power supply to test with. Any suggestions or should I just try to send my board back to seller? (bought it from Ebay
you can try a different USB cable and port, but all that connects the USB power to the Mega voltage regulator is D1; USB supply on one side and Vin on the other. check on both sides to ground and you should read your USB supply. If not, try supplying from a USB charger, you could very well have a bad USB port. good luck
Thanks for the tips guys. I did try with different USB ports with 2 computers and with an active USB hub without success.
Luckily, with external wall-wart 7.5v all seems to be fine and I can run the blink example! Well, I don't mind if the board works only with external power...
Well if all works fine with external power, including the ability to download a sketch then the only this that can be wrong is the USB cable not supplying +5vdc to the board, but allowing the two data lines to function. That would be pretty weird but certainly worth trying another USB cable.
Edit: I guess there could also be a problem with the board's auto power switching components on the board that prevents USB power from working.
