I just received an Arduino Mega 1280.
The board works fine with an external USB cable and powers up and sketches upload fine, however when I apply an external 9 volts power supply to the board via the barrel jack on the board, it doesn't get powered up. Does anyone know why that is?
Any ideas?
Thanks.
Are you sure that the polarity of the DC plug is right. I.e. positive to the middle and negative on the outside?
A lot of guitar pedal adapters use the opposite polarity. So, don't assume your PSU has the right plug polarity - test it with a multmeter.
Sorted it.
The voltage regulator on the board was faulty. Changed it and now it's all fine