Marlin: Z axes wont move, only buzzes

If you are positive your PINS, hardware micro-stepping and current are correct.. you should validate if the following options in Configuration.h are correct:

#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,25600,93}  // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE          {400, 400, 2, 45}    // (mm/sec)
#define DEFAULT_MAX_ACCELERATION      {5000,5000,50,5000}    // X, Y, Z, E maximum start speed for 

In the wiki page link you shared I've downloaded the Marlin version there and the values are completely different from the ones above.

Usually when I hear a Z axis is buzzing, I think it's probably trying to move too fast. So I would assume the max feedrate for Z or the homing feedrate were too high. But your Z speeds seem pretty low (compared to mine). These speeds can also be changed by GCode and saved to EEPROM, and you can change them from an LCD controller also. So you might try messing with the Z rates just to see if lowering them helps.

I would also check the microstepping and voltage on the Z steppers, of course. There _have_ been some additions to Marlin for digital control of stepper motor voltage, but that should have no effect on a RAMPS.

Are you able to test with RCBugFix to see if it fares any better?

@jbrazio @thinkyhead Thanks for your reply, it was actually a problem with the:
#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,25600,93}, the value 25600 was 10 times greater than supposed to, fixed the value to 2560, loaded it to the board and voila... Thanks for your help... I'd checked the code several times but never noticed the extra 0.

I'll let you know if I find something odd with this RC.