by RetireeJay » 2013-Oct-Wed-20-Oct

Here is the schematic of the Extruder stepper. The parts are labeled on the actual board.

The stepper motor is controlled by driving two different coils in the motor, 1A and 1B being one coil and 2A and 2B being the other coil. The controller chip detects how much current is flowing through the coils by measuring the voltage across resistors R30 and R31. These voltages are compared (indirectly) against the control voltage coming from the pot R29.



It almost seems as if one of your motor coils is not getting as much current as the other coil. It's possible that there is a defect in the controller chip; inside the chip, each coil has a "full wave" bridge, meaning that the chip can send current through each coil in either direction, and it's controlled rather precisely to generate the sixteen microsteps per full step. (MS1 and MS2 are connected by traces printed on the board, even though this is not indicated on the schematic.)

PrintrboardExtruderStepper.JPG



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Printrbot Plus operational January 2013

Brass threaded rods (5/16" X 18) & nuts for Z axis

GT2 belts & pulleys

Cable chain to reduce probability of fatigue failure in wires

E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally

PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan

Injection molded extruder gears

Optical Z "endstop" (custom designed and built)

Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex

Print on glass with Scotch Craft Stick or other glue stick

"My next printer is..." Prusa i3 MK3, upgraded to MK3S