A friend of mine who is 99% done with his Prusa i3 just called me with a problem. When he clicks Reverse in Pronterface, the extruder moves in one direction, but when he clicks Extrude, it moves in the SAME direction. He’s using Marlin on a RAMPS 1.4 board.
This sounds so familiar but I don’t know that it happened to me (I may have heard of it from someone else). Any guesses?
He tried connecting the extruder motor to the X axis and jogging x forward and backward, which does make the motor move forward and backward. He checked all of the wiring. He did NOT yet try connecting another motor (like the Y axis motor) to the extruder output, and seeing if reverse/extrude moves the Y axis forward and backward. He also did NOT yet try moving the extruder from E0 to E1 on the RAMPS board. He’ll try all of these tonight.
The direction pin might be shot from electrostatic discharge. I see it happen when people disconnect powered motors. Sometimes you can just replace the motor driver. Other times, it’s the digital IO on the motherboard.
I seem to remember him saying he’d swapped out the Pololu boards but I’m not sure. Hopefully him trying E1 vs E0 will test that. (Oh, wait, he’d need a 5th Pololu board for that… I don’t know if he has that or not)
You can change the pin assignments to swap E0 and E1. Or, if the firmware is already configured for two extruders, he could test it by just moving the stepper driver (and motor) to E1 and leaving E0 empty. It will probably require putting a 100K resistor on the unused thermistor port, though.