power suply

[wildwood109]

i have an old old old shopbot router made with unistrut the rollers run on that for rails,it came with no controlls,i need a power supply what votage do i need for motors #pk296a1a-sg3.6 vexta x&y, #pk268-02avexta z.i have a controll board geckog5404 axis.any help is grate wildwood

[ken_rychlik]

The 4g gecko based boards that shopbot upgraded these models to, use a meanwell 48 volt supply rated for around 7 amps. The original power supply that came with it was most likely closer to 24 volts. Changing how you wire the motors could dictate what power supply you would need.

How many wires are comming out of the motors and which ones will you hook up to?

Kenneth

[richards]

The Geckodrive G540 is the limiting factor. It can only handle 50VDC, so a standard 48VDC power supply would be the cheapest solution (6A or more. Use an external 10,000uF, 75V capacitor. Stepper motors do not draw constant current, so the external capacitor lets the power supply handle the huge variations in current draw.

If possible, wire the motors half-coil (Black to A [DB9-9], Yellow to /A [DB9-8], Red to B [DB9-7], White to /B [DB9-6] ). To reverse the direction that the motor turns, exchange the connections to the Red wire and the White wire. The PK296A1A-SG3.6, when wired half-coil can handle 80VDC without getting too hot, so the G540 will limit the top speed of those motors. Use a 1.5k, 1/4W current limiting resistor if you wire the motors half-coil, otherwise use a 1k, 1/4W current limiting resistor if you wire the motors bipolar series.

The PK296-02A works very well when wired half-coil to a G540. I have one that I'm currently running on my test bench. Use a 2k, 1/4 W current limiting resistor.

Half-coil wiring gives higher speed. It limits the torque to 70% of bipolar series, but the gearbox on the SG3.6 motors can't handle the full torque anyway, so 70% is more than adequate. When wired half-coil, top speed will be at least 2X faster before torque drops to an unusable level.