Question
Found error "FUSE" in window with unit in standby position, not on program run cycle, not attempting to water any station.  Replaced fuse with unit on standby, immediately blows with electrical spark on contact.  Problem in the controller itself?  Thanks so much for your time and consideration.

Answer
Thanks for your question.
I sounds like you already have the problem diagnosed. The controller is bad.
If you want to try a simple repair do this. Turn the selector switch (the one in the middle) around many times. Turn it clockwise and counterclockwise. Fast, slow. Don't be afraid of hurting it. Some of the RB LX models had a few problems with the selector switch, by turning it you may be able to get the switch to operate better. I've fixed a few this way. (It's not very scientific, but it worth a try) If the fuse blows again, then replace the controller.
Good luck,

Matt