hotend going crazy and heating up on it's own right away

bah.

so my prusa with sangiunololu is assembled and conecting to pronterface, and the last few days testing the xyz have gone mostly well (it seems to not move the entire length and the software stops it from moving, I don't get it)

but as of today when I turn on the machine, the hotend also begins heating. in pronterface the hotend is off int he drop down and I click the off button. I've tried reseting the machine via software and via the reset button.

what am I doing wrong? tad bit frustrting.

(also if anyone knows what's up with the axis not moving all the way via software that'd be great too...)

thanks

Hey Fyrebug,

What firmware are you using? I know for Marlin, which I use, there is a feature called software endstops. That means if the printer knows (or thinks) its at, lets say 145 mm from x home and the firmware says that it has only 150 mm to move total in the x axis, it will prevent you from moving all the past that 150 mm mark. If you look in the settings for your firmware you'll probably find a setting to either turn off that feature or at least update it to a larger value so you can move farther out.

As for the hotend, do you think that there is possibly a short somewhere? If you have a multimeter, I'd say start poking around to see if everything is proper.

bdc
~ Stay Calm Out There

More specifically, check the MOSFET that drives the current to the hot end. Few ideas:

1. With your multimeter, check the gate pin (pictures available here [www.redrok.com]). Current should NOT flow to the hot end if the gate pin has a low voltage (less than about 1V). If the gate pin is 0ish V and the hot end is still getting hot, your MOSFET is probably defective and needs to be replaced.

2. If the gate pin is higher than 1V, current will flow to your hot end, and it will get hot. If your hot end is getting TOO hot, either the firmware is misbehaving, or the firmware doesn't know that it's getting too hot because of the thermistor. If the thermistor circuitry is soldered correctly AND the thermistor isn't broken, then voltage on pin 1 of JP22 should go up as the temperature of the hot end increases. If it doesn't, then either your thermistor is broken or your thermistor circuit isn't soldered correctly.

Erik