Can't get the spindle speed to match Mach4 commands

[korbindallas]

I'm thinking my problem is also due to the resistor issue that was mentioned in another thread. I also have a 126/107 and ESS Smoothstepper and all spindle control functions are working properly and the 107 calibration routine ran perfectly with a full speed voltage taking my spindle to just a bit under the full rated speed (24000RPM) and the 30% taking it to just a bit over the recommended minimum speed (8000RPM). I have a tachometer.
My problem is getting a reasonably linear mapping of the speed settings in Mach4 to the actual speeds of the spindle. My measurements are here below

S23900  turns the spindle at 23961
S20000          "                    23961
S17500          "                    21420
S15000          "                    18365
S12000          "                    14665
S9000            "                    10970
S8000            "                      9740

I believe all my ESS,126,107and VFD settings are good as all else is working fine and the actual pin or jumper settings are consistent with documentation and settings noted in other threads in this forum. My ESS board is powered separately from the 126.

Could this be the same problem, a defective resistor on the 107, or is it something else?

Thanks

[Steve Stallings]

Customer had a calibration problem. The VFD was limiting the maximum output frequency to 400 Hz and he had continued to increase the gain of the CAL pot beyond what was required to reach maximum speed. This resulted in the lower speeds being shifted upward.