gene heskett wrote: >> Well there is two power supplies going to the amps so I am >> confused, please see the schematic here >> https://sites.google.com/site/bmklawt/home/control-schematic >> I don't know were the motor return line is >> > I think you will have to find it. There has been a discussion of grounding > here on this list just in the last 2 weeks or so, which your drawing isn't > complete enough to tell if its right or wrong. Basically, everyplace your > drawing shows as going to ground should go there on its own wire, and they > should meet at one common bolt. The Westamp servo amps in question appear to have a full isolation barrier between control circuits and power circuits. If that is true, it is not necessary, and may be undesirable to tie these two power supplies common. > There shouldn't be a measurable path to > this bolt from any wire that has been disconnected from this bolt, it is > the center of the 'star'. Any other ground will make a 'ground loop' and > the circulating currents will develop voltages that can mess with the > servo's. This could even call for remounting power supplies so they are > isolated from the mounting if they are internally grounded. > Yup, that is a concern. The fact that his Z axis appears to have abnormal transients even when disconnected from any command input at the same time the X has similar transients seems to indicate a ground loop **IS** to blame for this. There should be NO WAY that two amplifiers should have this kind of transient at the same time. When disconnected from the command source (the PPMC DAC board in this case) then the only connections I see are the +/- 15 V analog supply to the servo amps and the motor power supply, and the system ground. Somehow, something is being communicated between the X and Z amp that shouldn't be.
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