I have a 16" x 8" mini lathe. It's one of those generic, gray, chinese mini-lathes, no brand name associated.

Amonst other deffects, which I can work out, there's an irritating whining noise (high pitch noise).

I have removed the motor and checked that the noise comes from the motor.

I have also disconnected the motor from the lathe and connected another motor I use for other stuff and that I know to be quiet.

Regardless of the voltage provided both scream if connected to the lathe's electronics.

I read that the problem is the frequency used by the PWM module.

What can be done to get rid of this noise? I see a couple of adjustment screws in the electronics board but I don't know what they do.
(I haven't changed anything yet)

I can provide a video and a couple of pictures later. Thanks