Gen6 Stepper Buzz

Hello all,

I am new to the forum and 3d printing in general. I purchased a Prusa Mendel i2 from a friend. It has a gen6 controller running Marlin firmware. The printer has been sitting for a year without use and was never calibrated. For a power supply I am using a new ATX computer psu with a 12v/21a rail.

My problem is when I power the gen6 the steppers put out a really high pitched whine. I tried adjusting the pots and it does change the pitch but no angle will make it stop. I am able to connect to the board with pronterface and move the steppers and it even stops whining right when i connect to it but quickly starts back up.

I have tested all the steppers with an Arduino they can all move freely without the whine. Also I have an o scope so if you could recommend any tests I could do that would be great.

Thanks a lot,
Alec Karfonta

Edited 5 time(s). Last edit at 06/29/2013 05:42PM by alecKarfonta.

I was able to find the answer else where on the forum. Here it is for anyone reading this:

This was a problem with batch1 of Gen6.

In short, the squeal happens because the PWM frequency is in the audible range, you can fix it by swapping R36..R43 with 68K resistors.

The reason this isn't the default recommendation is due to the side effect of increasing the chopper frequency: increased power dissipation. You'll need to add heatsinks to the driver ICs. But, this will eliminate the noise.


Or you could also:

Switch to Sprinter firmware. Motors are off by default, until printing. Not a true solution, but much less annoying!