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Wiring issues

Discussion in 'Irrigation' started by VanDamnMan, Jul 25, 2014.

  1. VanDamnMan

    VanDamnMan LawnSite Member
    Messages: 61

    Hey all,
    Been lurking here a few months, but first time poster. I have a potential issue with a some wiring on a system. Took resistance readings from the controller and i was getting 30-35 ohms on each valve, the valves are Rainbird DVF100s. This seemed low so I checked connections and ended up redoing all of them after ohming out each solenoid. Ohms taken directly off the solenoids were in the upper 40's. I redid all connections and got the same ohm measurements from the controller as before. Anybody know what could cause a 10-15 ohm drop in resistance, nicked common wire maybe? The main concern I have is that there is 8-strand coming into the controller and just beyond a paver patio in the back is a box with two valves with 4-strand leading to them with no visible splice box in the area. :cry:
  2. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,163

    Unless you're having actual issues with performance, leave well enough alone. Benchmark the measurement at the controller for future reference and have a cold one. :drinkup:
    Posted via Mobile Device
  3. VanDamnMan

    VanDamnMan LawnSite Member
    Messages: 61

    Hi 1idejim, thanks for the reply! I should have prefaced what I said with that the controller alarm was being tripped so that led to me ohming the control wires. It's a Rainbird SMT, and if I ran a manual cycle of a minute or two per zone, the alarm would get tripped. Not necessarily on the same zone every time, sometimes on zone 1, sometimes on zone 3 or 4. Sometimes on the master valve which isn't even wired in. This controller also has a diagnostic feature to detect shorts but it isn't picking anything up. It seems the system has to run for a few minutes to get that alarm to trip.

    The thought that something screwy could be going on with the controller has occurred to me so the first thing I'm going to do is to swap out the face plate when I get back. Thanks for reading through all this, this one has me stumped!
    Posted via Mobile Device
  4. stebs

    stebs LawnSite Senior Member
    Messages: 495

    The fact that you're getting alarms in a master valve that you don't even have should be a flag for you...
    Posted via Mobile Device
  5. SoCalLandscapeMgmt

    SoCalLandscapeMgmt LawnSite Silver Member
    Messages: 2,118

    I wonder if this is an older controller with the MV issue that somebody upgraded to an SMT. You can buy an SMT upgrade kit that just includes the faceplate and the weather sensor. Could be a hardware issue.
  6. Without A Drought

    Without A Drought LawnSite Bronze Member
    Messages: 1,084

    unplug it and let it sit for a minute. it may have a ghost in the circuitry. I had an LX this year sending constant voltage to random zones. a hard reset cleared it up
  7. VanDamnMan

    VanDamnMan LawnSite Member
    Messages: 61

    Good point, I'll try replacing the backboard first and see if that resolves the problem.
    Posted via Mobile Device
  8. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,163

    Perform a short to earth measurement test.
    1) adjust the DMM to 2000kohms
    2) insert probe lead into earth and touch other probe to wire
    3) results above 5-700,000 ohms indicates no earth contact.
    Posted via Mobile Device
  9. txirrigation

    txirrigation LawnSite Senior Member
    from Texas
    Messages: 977

    Sometimes it takes a little while for the solenoid to heat up and short. Sometimes a valve will run for a few minutes before it shorts out.
    Posted via Mobile Device
  10. VanDamnMan

    VanDamnMan LawnSite Member
    Messages: 61

    Hi Jim,
    Thanks for the info on troubleshooting a potential short. I just have a quick question.
    The controller is an indoor mount, so can I test the wires from the valve box or should I splice in a length from the controller to the outside to check the resistance?

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