The dial on my Rainbird ESP 6si controller has stopped working. It is currently on OFF and I can't change the setting. I was told these models have that problem when I had a contractor come out to repair some electrical lines to my sprinkler system. Something about dirt and dust getting behind the connections of the dial. It is mounted in my garage. I only use 4 zones and would like to know what I could replace it with. I don't know if there is a standard voltage rating with all controllers and the sprinkler valves. I'd hate to fry the valves with the wrong controller. Would appreciate some help from the experts.