USB power only: Pin 4, VCCIO: 4.43v Pin 17, 3V3OUT: 3.35v Pin 20, VCC: 4.43V Adapter power only: Pin 4, VCCIO: 4.89v Pin 17, 3V3OUT: 3.35v Pin 20, VCC: 4.88v Adapter power, USB connected to PC: Pin 4, VCCIO: 4.87v Pin 17, 3V3OUT: 3.35v Pin 20, VCC: 4.87vby HyraxAttax - Sanguino(lolu)
Last week the heat bed of my Reprappro Huxley shorted the power wires, which caused the power adapter to shut off immediately. After screwing down the wires again, I plugged everything back in and got an "unrecognized USB device descriptor" message from Windows. The hotend fan turns on, and the cooling fans twitch, so it appears something is working. I switched the Melzi board to USB power, andby HyraxAttax - Sanguino(lolu)
Try disconnecting the input pin from the Melzi and plug in yhour printer and see if it still heats up. If it does, use your multimeter to check the resistance between the right pin of the MOSFET and the tab of the MOSFET. If there's little to no resistance, the MOSFET's gate is blown and the bed is receiving full power while the printer is plugged in.by HyraxAttax - Huxley
...or not. First time powering up the heating elements in three weeks. I first set the heater to 185 and loaded insome pla filament. Temperature settled to that point. I then set the bed to 70, and as it heated up things suddenly went wrong. The hot end spiked up past 250, so I turned both off through pronterface. The hot end continued going up and went past 400 before I could pull the plugby HyraxAttax - Sanguino(lolu)
Problem resolved. The resistor probably had an impurity in one of the leads, as it snapped off near the base when I tried to pull it straight out of the block. The new resistor works fine, as well as the fan.by HyraxAttax - Sanguino(lolu)
I had just assembled my RepRapPro Huxley last week, which came with a Melzi 2.0 board. I had been unable to get anything to really print decently even after setting the e steps and trying a bunch of different hot end and bed temperatures, so I tried using a cooling fan to see if it helped. I wired a standard 80mm computer fan to the board's fan connector and this is what happened: The hot endby HyraxAttax - Sanguino(lolu)