Back in 2005 I bought a 4AUPC REV. 1. For some reason it quit working. I purchased a new one (HobbyCNC EZ REV. 0) about a month ago. It doesn't seem to create as much torque as the old board. With the old one, the motors would squeal to where you could hear it with no problem and the steppers would get very warm. Neither of these happen with the new board. Do the new boards create lower torque?
Now, on to the problem with the old board. I would like to repair it and give it another try. When you power up the board, the steppers squeal with lots of holding power. After about 5 seconds, the steppers stop squealing and the steppers move freely by hand. The LM317 and the LM317AHV are extremely hot. Does anyone have an idea what the problem could be?