Question
I am replacing a new timer. The old one is a Richdel 300 series 1993.  The new timer is an Orbit 4 zone. I am having trouble with the wiring.  I plugged the green wire into the comm, and the other colors into zone 1(yellow), zone 2(red), zone 3(white).  The one giving me trouble is the blue wire.  I tried plugging the blue into any zone and when I press start for the blue it blows out the fuse. So, where am i suppose to plug the blue wire?

Answer
You need to identify which wire goes where. Take a look at your valves, there should be one wire which is connected to each of them.  This will be the common wire.  That neets to connect to the comm terminal.  It is most often the white wire, but it could be anything.  The rest of the valve wires need to be connected to terminals, only if they have a corrosponding connection to a valve.  I hope this helps.