Any reason why I feel the PTC getting hot on a UNO using a 12Vdc external supply? The board works with the external supply but the heat worries me. Isn't the PTC for the USB?
I agree, that seems wrong. Could there be a piece of metal stuck in the USB socket?
I have discovered the problem. I was using a 12vdc supply, in which the 5v regulator was heating the thermal pad more . The regulator being next to the PTC was getting hot. It fooled me. Switched to a 9vdc supply a lot less heat . Has been running for a whole day with a 2X16 LCD and is doing fine.