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Non-working stepper drivers

Posted by darkestelephant 
Non-working stepper drivers
March 01, 2014 02:48PM
No motors work properly :
I am using 4 x A4988 with my RAMPS 1.4. The y axis is completely dead, the extruder only occasionally locks, the z axis just buzzes and the x axis can only move in one direction in the smallest increments. All are with heatsinks and the trimpots are set to 0.4v. The firmware is Sprinter uploaded from Arduino 1.0.5 and controlled by Repetier-Host.
Also, the power is a 240w 12v 20a led switching power supply. Can the problem be with too thin wires? Or the wrong sort of stepper motors?
Finally, the temperature readings are at ~130C constantly and a cannot find the correct setting. (100k, b value 3950, ntc, reads 471 with multimeter at 2000kohms - this is at ~15C)
Thus, the bet & heater do not work. I am stuck with a pretty useless printer.Should I try and buy different electronics/ motors/ thermistors?
Thank you for any help
Re: Non-working stepper drivers
March 01, 2014 06:26PM
Try adjusting the acceleration seting in the config file, you may have to slow them way down. Did you adjust anything in your configuration. h file? Set your themsister table? Set your endstops? We will need more information about your printer and set up to answer your other questions.

Edited 1 time(s). Last edit at 03/01/2014 06:31PM by cat.farmer.
Re: Non-working stepper drivers
March 01, 2014 09:09PM
If your thermistors are stuck at a set reading, then either you have the wrong board config (it's reading the wrong pins), or you've somehow connected more than 5V to the thermistor inputs, frying them. If you've fried the thermistor inputs, then you need to replace the Arduino Mega.

Check for resistance between the thermistor leads and the hot end, and beware of intermittent shorts as the hot end heats up (eg: wires bending under heat, then touching).
Re: Non-working stepper drivers
March 02, 2014 03:44AM
The readings do change, so they are in the right pins but I don't know if I have damaged them. In configuration.h they are just 100k thermistor. I have not made a thermistor table.
What should acceleration be changed to? There are the 3 min endstops on my Prusa i3.
What information is required?
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