I was using using an ATX PSU (500W) with my RUMBA for a while now, but I just replaced it (because it liked to shut off in the middle of prints, and the 1A load on the 5v trick didn't work) with a dedicated 12v 30amp power supply. I have everything wired up, and I can get the board to turn on with the new supply, except USB communications doesn't work. Thought I burned something out, but when I went back to the ATX PSU, everything was fine - or at least the USB communication still worked. I assume it would still have the shut-down issue, let's not worry about that for now. I want to make sure im not missing something before I accuse the 12v supply of being cheap (which it is) and broken (which im not sure about). For diagnostics i've got a cheap multimeter. Nothing like an oscilloscope, that would be too useful.
Not sure if it makes a difference, but when I move the jumper to "USB power" from "stand alone", I still need the separate power supply (the ATX PSU). Some USB ports do nothing, some make the power light blink for a second, then turn off. I'm not sure if the USB power option used to work, I thought it did.
Not sure if it makes a difference, but when I move the jumper to "USB power" from "stand alone", I still need the separate power supply (the ATX PSU). Some USB ports do nothing, some make the power light blink for a second, then turn off. I'm not sure if the USB power option used to work, I thought it did.