Question about VPI Power Line Conditioner

What is the potentiometer on the rear of the VPI PLC used for? Does anyone have a manual I can get a copy of?
Thanks !
you can check vpis web site,
From the Owner's Manual for the VPI Power Line Conditioner:


"The new PLC has a variable control on the center rear panel for adjusting the final output voltage to the turntable. Rotating the control clockwise till it stops will give full output voltage. Turning the control fully counter-clockwise will drop the output voltage roughly 40%. Try to lower the voltage as much as possible for the lowest vibration from the motor. This will give the best sound. If you go to low, the motor will not run. We have adjusted this at the factory for a sample turntable. You can fine tune this on your own unit. This control does not affect speed, only noise from the motor."