Check the external input power?

Hi this is my first post! :stuck_out_tongue:
I have an Arduino MEGA-ADK. I build a simple testing scheme to light up a LED with a sensor. And when it is plugged into the PC’s USB works perfectly. But when I turn on a external power 12VDC, 1A, positive internal source, nothing happens. Nothing at all. No light or LED on the Arduino board works. :frowning:

Does the external input is damaged? How could I check?

First check is to measure your external power source with a multimeter when it is not plugged into your arduino and post your findings.

Hi retrolefty! I measure 12.2V. It is irrelevant difference between the specification and the measured.

AlamBaier: Hi retrolefty! I measure 12.2V. It is irrelevant difference between the specification and the measured.

That is fine. Was it a DC or AC voltage? Next question is what is the current rating of the voltage source?

Next test is to plug voltage into external power connector and then measure between the Vin shield pin and a ground pin. Post reading.

Then ... Is Measured DC voltage. I plug and measure between the Vin pin and the shield ground pin and v is 12.2 (I do not think of it before). But the Arduino Board remains dead when plugged into external power.

AlamBaier: Then ... Is Measured DC voltage. I plug and measure between the Vin pin and the shield ground pin and v is 12.2 (I do not think of it before). But the Arduino Board remains dead when plugged into external power.

Then you appear to have a defective on-board +5vdc regulator chip. Good voltage (Vin) into the regulator, but no +5 vdc out of the regulator (no power on LED lite?). Maybe bad solder connection on pins on the 5 volt regulator?

Thanks for help! Could you tell me how/where I find this connection on pins on the 5 volt regulator?

AlamBaier: Thanks for help! Could you tell me how/where I find this connection on pins on the 5 volt regulator?

Assuming a Uno board. It's the component right next (above in the picture) to the external power connector with three leads on one side and a heat sink lead on the opposite side.

https://www.sparkfun.com/products/10524