Arduino Uno Wall Wart Touch chip = Instant Burn


So I have been playing with my Arduino for a while, and decided to plug in a buzzer and have some retro fun! I plugged my Arduino in with USB, uploaded the 'Blink' program, and then unplugged from USB and plugged into the wall. I left it running while doing some things, and came back to find the bottom of the board, in the area of the voltage regulator, hot to the touch. I quickly unplugged the Arduino, and left it to cool. Coming back, I felt the back of the board and it was not hot. So I plugged it into USB, and started coding. I felt on the back of the board, and noticed some heat. I felt around the top, and the chip circled above burnt me instantly!

This is probably not normal, I am wondering if there's anything I can do to stop this. Thanks!

That chip is the LM356 that does the autopower sensing.
Did you have an AC adapter plugged in by any chance? That comparator shouldn't be hot.
It does drive the L LED also.
Trying to picture a scenario that would make it hot.

Did you have an AC adapter plugged in by any chance?


The adapter shown all the way on the left is the one I am using. It shows the symbol shown on the Arduino Power Supply page, so I assumed its ok, it outputs I think 12V, unless the 100-240V AC Input is the one I should be looking at...
I had it hooked up to an external LED with resistor, and it was blinking just fine. The L light stayed on though...

Bad sign. It didn't blink the LED attached to the pin when I started it up, and it won't let me upload. I took out my ATMEGA328 (which I presumed was fried) and tried my known working ATMEGA168, and it didn't work either (wouldn't show anything apon hitting reset, and uploading didn't work) Did I fry my Arduino board? :frowning: