Centroid Community CNC Support Forum

I do not have an oscilloscope to analyze this. Here is what I know: 1. When running in test or jog mode, the spindle encoder reads a fairly stable rpm. 2. When the servo is controlled by the analog signal, the spindle encoder shows a bouncing, unstable rpm. 3. The servo driver has the ability to dis...

No luck at all. I removed the connectors and now the shielded cable runs directly from Acorn to JMC Servo.... But the signal is still bouncing up and down. Not sure what to try next. Maybe install a few Ferrite Toroid Cores if the noise is coming from the servo driver.

I did some further digging and think I found the culprit. The wire running from the Acorn to the servo exits the enclosure, then passes through a pair of DB9 connectors (Not sure what I was thinking :o ), then proceeds to the servo. The cable is a shielded cable that has drain wire and foil shield. ...

Ok.... I found the document that addresses minimizing EMI for VFD's that I used when I wired this thing originally. See number 15 that I highlighted. This document is from Automation Direct.

Nigel. Thanks for sharing the link to your impressive spindle rpm project. I read through it very carefully. The only thing that sticks out to me is that the shielded wire I am using (https://www.ebay.com/itm/233698319416) is NOT grounded on both ends. It is grounded on the Acorn side. Does anyone k...

Thanks... I am looking through the drive manual... There are some notch filter parameters but these appear to be relative to resonance associated with system rigidity... More reading to do.

I reread the information from the post that addresses using filters to minimize noise in the analog signal. Here is the post: https://centroidcncforum.com/viewtopic.php?p=45986#p45986 This post explains that the addition of a series resistor + a .1uf capacitor added in parallel to just a single .1uf...

Thanks. I just verified that I used a ceramic disk capacitor. I will remove the resistor and other capacitor and cross my fingers.

Thanks for your help... Richard

Hello Nigel,
The attached is the snubber circuit that I am currently using that was suggested by Uwe. This is wired across the analog output on the Acorn board.
Are you suggesting that I replace this with just the .1uf capacitor?

I tried a different filter as shown below with no change at all. I even tired rerouting the analog signal wire that goes from Acorn to the servo and it made no difference either. I set the servo to display the analog input signal, and the digital display bounced around confirming that the analog sig...