Pretty Sure I Blew My Voltage Regulator...but want to double check I seem to have made a terrible mistake with my Mega 2560. I had it connected to a 12v 1amp wall wart with the following:

  • Ethernet Shield
  • DHT11 Humidity/Temp sensor
  • SparkFun Logic Level Converter - Bi-Directional
  • TSL2561 Lux sensor
  • 2 PowerSwitch Tail IIs

They worked as expected for a few seconds (about 10?) but then most notably the lights connected to the powerswitch tails would turn off. A little perplexed, though suspecting a power problem (as I'd had everything set up with a 5v 2amp wall wart and things were fine) I connected my multimeter to the 5v power pin, unplugged and reconnected the wall wart. Things came on for less than a second and then went out...and then I noticed a nasty smell. I grabbed the board and it was warm (but not super hot) near the voltage regulator and now the barrel jack will not power the board (but the USB will!).

I am trying to figure out 2 things:

  • Considering the AMS1117 voltage regulator is rated up to 1amp, I figured I wouldn't really have to worry about frying the regulator with 12v 1amp no matter the load (as the wall wart would at worst not be able to supply enough power). Seems that's not the case?
  • Is there a way to test out the regulator while still on the board?

I apologize if this all seems pretty stupid, but any advice would be greatly appreciated!

I suspect you have used an unregulated 12volt supply.
Some are close to 20volt without load.

The AMS1117 is rated up to 1Amp and up to 15volt. But not both at the same time.
Power (heat) in the regulator is voltage difference (Vin - 5volt) times current draw.
I think 2watt is about the limit for a Mega.
Not sure what the power tails are using. Post a link.

The regulator and/or the reverse protection diode between DC jack and regulator could be blown.
The diode (D1) can be measured with a DMM.

Post a photo of a hand drawn schematic.
Your on board regulator is probably blown.

As Wawa implued, ger a DMM and measure the unloaded output of the 12V wall wart.