Steppers Not Working Properly

Hi, I am building my first Reprap, I dont have too much electronics experience but i know the basics. Up until now, all of the hardware is mounted, and when I finished with the electronics, I programed the arduino, ran Pronterface and connected the printer. When I try to move any motor, it makes a weir sound, and vibrates. This is the first time I turn on the printer. The only thing the printer doesn't have are the endstops, which are mounted but not connected since I am waiting for the cables to arrive by mail. Are the endstops not conected the problem? Is there enough power getting to the motors? Any help will be very apreciated

I have the same problem - But on a Kossel Mini with Sainsmart RAMPS 1.4 and Sainsmart Mega board. Configured the firmware with Repetier 0.91 v4. I do have an ATX computer power supply rated to 305W connected to both of my Power IN connections. I can manually enable the j-head cooling fan, the heat extruder, the heated printbed, and verify that all those are working.

Attached is my configuration.h file and a pic of my board with the servos connected.

Not having the end stops connected can be a problem, it will stop you from moving towards the switch, but you should be able to move away from them.

This sounds more like you need to adjust the trim pots on your stepper drivers.

Sainsmart apparently does not tweak their A4988 drivers to any consistent vref setting before putting them into baggies to ship. Of the six that I received, the vref varied from 0.28V to 0.36V. Ideal for my steppers is allegedly 0.40V, which is where I have them set now and it also cured my mis-stepped errors on one stepper. If you haven't done this yet, look up the directions for setting vref on the wiki and break out your multimeter before you go any further.....

You can rule out the endstops with an M119 command, which will display their status. If any are triggered, that axis might only move in one direction. One the cables arrive, trigger each endstop one at a time and verify that they are triggered with an M119 command.....