RAMPs with test code causes motors to sputter

Greetings all,

Its my first build of a Prusa Mendel using RAMPs 1.4 shield on an Arduino Mega. The problem I am having
is that the motors are not turning properly with test code. I am using a two-channel lab power supply that
has variable 0-20V / 0-5A supply per channel (just to be on the safe side, I want to see the board work with
this before applying a hacked ATX) The code in question is this :

[reprap.org]

which causes the motor to jostle back and forth quickly and randomly, rather than turning the motors a full cycle. Some
thinking/reading has suggested this is due to insufficient current being delivered, but if I turn the current on
the lab supply up, the motors jostle faster rather than completing a turn. After testing the other RAMPs motor
ports, all other axes X,Y,Z and E0/1 yield the same effects.

I don't know enough about how the RAMPs board works to control the steppers (any info would be appreciated?)
to try to write my own test code, and playing with the timing of what I am guessing are pulsed signals that the
code is generating with the mills() command hasn't changed the output much. The current draw is about 0.5 A
per motor, and I have tried adjusting the screws to draw a bit more current into the steppers to no avail.

Any ideas? I'd really appreciate a hand with this.

Thanks much,

Charlie

Looks like your motor wiring isn't right or interrupted. Don't trust wire colors, check with an ohm meter wether one coil is on the left pair of pins of the connector, the other coil on the right pair.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Yes check wiring when I first time run my ramps then I got same issue green and red wire was swapped in wiring which I done so first I blamed seller then I damaged one driver by doing strange experiments with it (luckyly was 5 in set) and at last I checked wiring and this was the reason.

Thanks, the motors are humming nicely now!