I have been using a CNC xPRO V3 board successfully with my OpenBuilds MiniMill for the past several months without any problems. I recently hooked up an accessory board (made by a friend) containing MOSFETS to control my spindle (i.e. router) and solenoid valve for coolant. I tried hooking up the spindle signals first. The xPRO worked fine with the accessory board and a relay to turn the spindle on and off. I used the exact same parts (MOSFETS, relay, diodes, etc.) and configuration shown on the Github site. I proceeded to hookup the solenoid (yes I used a flyback diode). When turning the power back on to the board after connecting the solenoid through the accessory board, I think I heard a pop and smelled something burning. I noticed I no longer had lights on for the stepper drivers, but the 24V, 5V and USB comm lights were on. I could still turn the spindle on and off, and I could now activate and deactivate the solenoid. However, I still had no lights on for the stepper drivers and I could not move my stepper motors at all. I tried everything I could think of by disconnecting and reconnecting things. I checked voltages and all are correct (when activating either the spindle or solenoid, I get 5V from the xPRO to my accessory board and 24V out of my accessory board). I can still turn the spindle on and off and activate/deactivate the solenoid, but no power to the stepper drivers. Did I just fry my xPRO? If everything else is working, what could have happened? Can anyone suggest some diagnostic techniques to help me? Please keep in mind I'm not very electrically inclined.
I had connected my stepper motors to the board via DIN connectors mounted in the wall of an enclosure box. One of the wires soldered to the DIN connector for my z axis stepper motor was not soldered well and broke loose. It shorted with another wire and shutdown all of the stepper drivers. After discovering the broken solder joint and repairing it, I still did not have power to my stepper drivers on the board (no lights). I happened to read a reply to my same post on the Github website talking about how I had my Emergency stop button configured. By luck, I started wondering if the broken wire and short triggered an Emergency stop. I pressed my Emergency stop button and then reset it. After resetting it, power came back on to my stepper drivers.