I have Arduino UNO R2 board and Arduino UNO R3 board. I think that the Arduino UNO R2 board may have bad pins because the project worked on Arduino UNO R3 board but not on Arduino UNO R2 board. The project has Parallax Joystick controlling two continuous servos. Both servos work on Arduino UNO R3 board. One servo work and other servo doesn't work on Arduino UNO R2 board. If I switch data wires, the other servo works and the servo that worked before stopped working. How do I test the pins on the Arduino UNO R2 board? Do anyone make good breadboards, headers, and jumper wires? I may have bad breadboards, headers, and jumper wires. The Arduino UNO R2 board passed the loopback test.
How are you powering the two servos, from the shield 5v pin?
Lefty
I think that I powered the two servos from the shield 5v pin before connecting them to separate power source.
I tested the Arduino UNO R2 board using the "Blink" code and found out that pin 9 may be dead and that pin 11 is stuck "on" and the LED stayed "on" and doesn't blink. Is the board damaged?
The chip probably is. Replace the ATMega328P-PU with another; you can use the R3 board to put a bootloader on it if you buy a blank part.
Here's a tutorial by the Arduino team!