Hello, i have an arduino uno. it works very well, but the voltage regulator on my was getting hot around 50 - 60 ºC. it was different from the one of website of arduino.
mine
How hot the on board regulators is a function of the following:
External voltage value, 7-12vdc. The closer to 7 volts the better for less heat dissapation.
How much external current any wired components are using of the board's +5vdc power.
Note that voltage regulators like this will automatically shut down if they get too hot or you draw more the it's rated maximum output current. So while hot is not good and should be avoided, it's not likely to damage the board.
Lefty
i use a 9vdc unregulated wall wart.
my worry is about damage the pcb itself. this is possible?
I already answered that.
I think the unregulated ones can often deliver more than their ratings, particularly at the low current levels the Arduino draws. Try measuring it with a multimeter. Sounds like it might be putting out 12V. Try a regulated 9V supply.