Shawn wrote:It's coming from the power supply for the PowerPro. If there was some insulation or ferrites or something to add maybe that would help, I don't know. But it is coming from the power supply. Doesn't appear to affect the performance as far as I can tell so far, but I have not put it through the ringer yet. Been doing upgrades and maintenance.
I am hesitant to give advice here, because
a) I don't own a PowerPro
b) I don't know the internals of the PowerPro so I am just guessing on limited information
c) I only dabbled in switched mode power supplies (SMPS) during my career and it was DC-DC SMPS...so I am no expert in this area of AC SMPS
Okay, with those disclaimers, here goes...Putting an input filter on would only prevent PowerPro EMI from getting back into the power lines and affecting other equipment (hence my questions about nearby radio, tv, etc). Another function of this filter is to prevent any high frequency coming in on the power line from affecting the output voltage of the SMPS. So, you could try this, but I am doubtful it will "fix" your static issue because I have my doubts this would cause an auditory component emanating from the PowerPro itself, but it could.
So, what else could it be? I need to stress that the PowerPro is a black box with very limited documentation shared outside of Shopsmith. Striatech designs and builds it and is actually quite helpful if you contact them for information. Unfortunately though, Shopsmith licenses their particular DVR motor from Striatech so I think Striatech is limited on what they can share on the PowerPro product with customers. Still it could be worth a shot to contact them and just see what they say regarding this static noise issue. My guess is they will tell you it is time to change the power supply. Again, the PowerPro is a black box, but we do know that it is a switched reluctance DVR motor design. The most common way to power a switched reluctance motor is through an asymmetric bridge converter, which typically has a capacitor on its output to limit electrical and acoustic noise. If the PowerPro skipped putting a capacitor here, or if the cap is old and degrading this could explain the problem you have. I wouldn't advise trying to implement a fix yourself. Even with full schematics, a SMPS can be a dangerous thing with high voltages stored even when turned off. If this is the cause of this noise, it is likely not causing any damage so you could just live with it. On the other hand, if you want to fix it, perhaps go the Striatech route to get their opinion. Then with all information, try to convince Shopsmith that they need to replace the power supply on your PowerPro. Below are a couple general documents related to switched reluctance DVR motors if anyone is bored and wants to read them related to this:https://en.wikipedia.org/wiki/Switched_reluctance_motorhttp://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.921.1721&rep=rep1&type=pdf