"[Benji, Zax and the Alien Prince][1]"(1983)?    
It was a Saturday morning show(not animated), and it did also feature an evil robot, I think in an episode called "Decoy Droid"?

Here is a picture of the yellow droid.      
[![Yellow droid][2]][2]


  [1]: http://www.imdb.com/title/tt0147747/?ref_=nv_sr_1
  [2]: https://i.sstatic.net/FfwaP.jpg