by ALittleSlow » Fri Dec 28, 2012 12:21 pmMy MTRMX-Nx was working fine last night. I unplugged it from power and shut down the NXT. This morning I made a software change, but when I tried to run the program I got no activation of the motors attached to the MTRMX-Nx.I am using a power supply rated at 12VDC, 750ma. It shows 13.5V at the MTRMX power connector at idle.Last night I was using it to power a total of 6 PowerFunctions medium motors (two pairs of motors on two ports and one motor each on the other two ports). I ran this setup for about four hours for as long as 15 minutes continuously. The ICs were not noticeably warmer when running than when idle, and were never hot.This morning, I made no changes to the electrical or mechanical configuration. The most significant software difference was that I moved the SetSensorLowspeed() command from just before the I2C commands to--nowhere. That is, I intended to move it, but only succeeded in deleting it. Does this mean I attempted to drive the MTRMX-Nx in analog mode?When the MTRMX-Nx is plugged into the sensor port, its LED blinks 3 times, the 4 times (I think), just as it has always done.To troubleshoot, I disconnected all but one motor, unplugged the board from power and from the NXT, and pulled the battery from the NXT. Then I shorted the power connector leads on the MTRMX-Nx until it showed 0V. After reconnecting, I ran the MTRMX-Nx demo program. Still no joy.Any suggestions on further troubleshooting or on what might have caused the board to fail?