Sprinkler Valve Question

Hi. I'm having a problem with the sprinkler valve on my next door neighbor's system. It's an Irritrol 2711DPR valve...and it works fine loosening the "manual" screw... but when using the controller, the solenoid hums, a momentary gush of water comes out the sprinklers, then cuts back to just a trickle. All the rest of the sprinklers in all other zones work fine. Voltage is the same as at the other valves...26.3 vac. Could this be dirt in the valve? If so, why would it not affect performance on "manual"? If it is dirt, are Irritrol valves easy to disassemble?...and anybody have any idea what a small tab on the valve marked "<on-off>" does? Thanks in advance.
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On 6 Feb 2006 08:21:20 -0800, snipped-for-privacy@yahoo.com wrote:

Not familiar with that valve, but I've replaced several of mine over the past 20 years or so. Mine are all buried and I wouldn't waste time repairing one when a new replacement is more cost effective in my situation.
Regards,
Hal
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Sounds to me as though you have a normally closed solenoid valve. i.e. unless the solenoid is energized the valve is closed. The solenoid is actually an electromagnet that when energized pulls the valve open allowing the passage of water through the valve. If the solenoid goes weak and opens only partially then that would explain the trickle of water. The momentary gush may be that initially the solenoid develops enough magnetism to open the valve all the way or most of the way, then the magnetism weakens and the valve closes most of the way.
If the solenoid itself is easily replaced then that will probably solve the problem. If it is more cost effective to replace the entire valve then that too would solve the problem.
Mr. Bill
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