If this is Louis Allis then you must be using a tach motor rather than an encoder for the speed feedback. Check your dc tach for AC ripple. You can use a scope but an old Simpson or Triplett with an output lead connection works just fine. Verify you don't have a carbon problem in the tach particularly if the brushes are oriented at 12:00 and 6:00. Also check all the ribbon cables in the drive for proper connection. Louis Allis drives have poor clips on some of the connections and this causes problems if the drive swing panel is open and closed. How is the drive tracking? Louis Allen drives typically needs more lag than most newer drives. You will need a scope for this part. Using a scope set one channel to observe your speed reference and the other channel to observe speed feedback. Put the signals on top of each other and see how well the tach follows the pattern. Have you checked your loop circuit for grounds? Improper current feedback will cause trips as well, thus the need to make sure your loop is clean. Most drive problems come down to problems with your feedback loops. How does your brake look? Check for signs of bluing or glazing on the brake drum. An intermittently dragging brake can cause plenty of problems.
Last edited by Smitty; 06/02/11 09:15 PM.
