Re: missed keystrokes problem, back with a vengeance.

[Jerry Stuckle <jstuckle@attglobal.net>]

On 1/29/2017 1:48 PM, Gene Heskett wrote:
> 
> Alan, ALL of the motor drivers are switchmode, with the current 
> regulation running at or above 20 KHz. And these noise spikes are 
> ringing at nominally 100 MHz. I have managed to get the xy motor noise 
> under control by takeing out the switchmode psu's, and putting in 
> tordoid transformers, bridge rectifiers, and the biggest electrolytic I 
> had in the drawers that had sufficient withstand voltage.  Its a star 
> ground system, and the output cables to the motors are shielded, and the 
> shield grounded as it goes by this single bolt ground on its way out of 
> the box. The shielding extends both ways from that point but is not 
> connected either at the motor, or at the driver, just at the bolt.  This 
> is std in such noisy machinery.
> 

I would also recommend bypassing those electrolytics with 0.01uf or so
disk capacitors (or similar).  Electrolytics have higher impedance at
higher frequencies.  Bypass capacitors help with high frequency spikes.