buzzing servo

[harvard5]

I got my mill running and I'm having a problem with one servo buzzing. It looks like it's trying to move all the time and if I comand it to move the control shuts down (crusader II) with a servo disconnect fault code. I think it has something to do with the servo's tach (encoder?) and its setting. does anyone know how to set up the tach/encoder on a S.E.M. servo motor? I tried the company but haven't heard back from them. I have the trouble shooting guide for the control but it dosen't tell me how to set the servo up just the control board.

thanks again Bill

[Al_The_Man]

It sounds like you might have a bad servo amp, or at least one that needs adjusting, What type of amps do you have? Also try swopping two drives over if they are all the same size.
There are a couple of ways to test the motor/tach/amplifier. Firstly, if you can easily disconnect the motor drive and with the power off, spin the shaft by hand and monitor the voltage on the tach leads and see if you get a +- voltage swing output polarity will depend on the direction of the rotation.
Secondly, disconnect the motor drive and the analogue input signal and if possible wire a 5k~10k pot accross a 9v battery to supply an input to the amp and see if it rotates ok.
I assume this is a mill that has been running ok up till now, or is this a new installation?
If you have older Westamp drives on it, they were prone to component aging problems, swop one out as above. If you post the kind of drive you have, I may be able to help with the setup.
Al

[harvard5]

I have the Glentek type servo cards. I swapped the X and Y axis connections and the problem followed the servo motor,it wasn't as bad so I think it just needs adjusting. I took the servos in to have them checked over and won't get them back untill next week so I'm on hold untill then. I do have a copy of how to set up the boards so I'll give it a try when I get the servos back.

thanks Bill

[harvard5]

It works! I got the servos back, one needed new bearings and the other had the tach set. I balanced the servos and found a backlash problem on the Y axis (fixed with a shim between bearings. Now I just have to learn how to program it! and someday get the parts for the quill drive.