I have recently assembled a cnc shield system with NEMA 17 motors with a 12v 30A psu. I set the votage to 12v on the nose. I plug it in and activate the motor and it blew the fuse. I soldered a small gage wire as a bridge in place of the fuse. It worked for awhile then the negative lead on the PCB burnt up. I have tried multiple 3 cnc shields with similar results . I also turned down the pot on the drv 8825. I don’t know what else to do. Also when the i try to activate the x axis after it stops working, the y axis motor engages but doesn’t turn. Any help would be greatly appreciated. I’m wondering if I have a bad motor, but all three of them seem to work OK when the system works.
If you want any help, you must identify the CNC shield and the motor and draw a schematic of how you wired them up.
deaglx: I soldered a small gage wire as a bridge in place of the fuse. It worked for awhile then the negative lead on the PCB burnt up.
That sounds like you don't understand the purpose of a fuse.
Post a link to the datasheet for the motors and for the CNC shield.
20A is a lot - how many motors are you driving? You have individual DRV8825 modules per motor? Which motors?