I am using Mach3 to control my spindle.  I can turn the spindle off and on using Mach3, but the spindle only runs at 2400rpm. 
Motor Outputs:  Spindle enabled  step and direction pins both 0  direction and step low active both not checked
Output Signals:  Enable 1  enabled  port 1  pin 14 active low not checked
                         Output 1  enabled  port 1 pin 17 active low not checked
Motor control:  use spindle motor output checked
                       pwm control checked
Spindle Pulley 1 min speed 0  max speed 24000

And when the spindle is off no matter what I do there is 10volts between pin 17 and ground.

Attached is my schematic.  Thanks for your time.

PWM on the Chinese 5 axis breakout board is on pin1.