1.

Explain testing, fault finding and repairing of dc motor.

Answer»
  • Remove the springs and brushes by removing the cover typically with a slotted dcrew driver 
  • Check the motor brushes are moving freely when disassembling 
  • Check that the spring tension on all the brushes are about equal 
  • Check the face of the brushes- it should be shiny or polished which will indicate good contact. If not replace 
  • Check the brush length. Typical fanuc DC motor brushes when new are about .75" long. The less length the less spring tension on the brush. 
  • Ounce brushes are removed shine a flashlight inside and look to see if there is build up on the commutator or in the housing. Use an air line/clean air supply to blow this out. Clean between all the commutator grooves and area for brushes. If the is black residue on the commutator polish with fine sandpaper. 
  • Check for wear grooves on the commutator from the brushes rubbing. Consider replacement if extremely worn or pitted.


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