Multiple zones been turned on at the same time
I got this problem of multiple zones been turned on at the same time, hope someone can help me resolve it.
The controller is RainDial RD600, and the whole system is been running fine for more than 12 years. Just recently I found the water pressure was very low, then I noticed several zones are turned on at the same time, which is not suppose to happen, which causes the water pressure very low coming out of the sprinklers. Then I did some studies and investigations.
1. The RD600 seems working fine, as I measured the output control voltages, using a voltage meter, are all correct. Only the "Master Valve" and one of the zones turned on at any one time.
2. I measured there are no shorts between the control terminals, ruled out possibly cross-wires.
3. I tried to just apply 24VAC to "Mater Valve" to turn only the master valve, then zone#2, #4, #6 are all turned on.
What could be the problems with the system? How can I fix them? Thanks in advance.