I have a uno rev 3 board that had an accidental encounter with 12+ volts somewhere underneath board, looked like main chip overheated (small spot looks melted) anyway so i ordered two new chips fir it an atmega328 from eBay and an atmega328p from digikey both supposed to have bootloaders burned on them already, well neither chip seems to work all I get when i upload a sketch is “avrdude: stk500_getsync(): not in sync: resp=0x00” sometimes when i plugin usb cable it will do 3 rapid flashes pause the again 3 rapid flashes or on off 1 second intervolts, yes i tried loop back test but it did not work
If the loopback test doesn't work it's the USB-to-Serial that is broken. If you are lucky it's just the firmware that got fried and the hardware is still good. If so you can use the DFU process to restore the USB-to-Serial:
johnwasser: If the loopback test doesn't work it's the USB-to-Serial that is broken. If you are lucky it's just the firmware that got fried and the hardware is still good. If so you can use the DFU process to restore the USB-to-Serial:
Thanks for the link but the from what little I know the directions are for an earlier model arduino I noticed the back where you solder the resister on is not same as the R3 model I have, thanks anyway, wonder if I could just replace the chip on the board
Read this comment on the hardware page, search for "ATmega16U2": http://arduino.cc/en/Main/ArduinoBoardUno
Reprogramming the firmware via DFU is far (far) easier than trying to replace that surface mount chip... which would probably need to be programmed anyway once you did it.