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60.4 ohm reading - Bad connection???

Discussion in 'Irrigation' started by AceSprinkleRx, Jul 21, 2005.

  1. AceSprinkleRx

    AceSprinkleRx LawnSite Member
    from Wyoming
    Posts: 95

    Get a call this morning that Zone 8 doesn't come on by the controller, but will start manually. So I begin a system check in my mind on the way over to the house via recalling sections of 'Troubleshooting Irrigation Controll Sytems' by Derryberry.

    Initially I figured it would most likey be a diaphragm or solenoid causing the trouble.

    I begin by ohming all the stations and they all fall between 56.1 and 57.9, normal, except for station 8. Station 8 reads 60.4. According to Derryberry, readings between 60-100 indicate faulty connections. I'm thinking, "Dang this is close to a normal 60 reading - but it is over the 60 threshold."

    Derryberry says to trust your readings. So I make the call.

    I check the voltage on the #8 timer switch and it's good so I and rule out the switch. We go to the valve box to ohm the solenoid and I inspect the connections as I pull the waterproof nuts off. The solenoid ohms out good. Not the controller, not the valve, not the solenoid.

    With 4 solenoid wires and the common twisted together, the #8 wire does seem a bit frayed, but not badly enough to not be making contact I thought. I clipped and stripped the 5 wires, reconnected them all together and slapped the nut back on.

    We go back to the controller (did I mention he followed me like a puppy dog?) and ohm test #8 again and it now reads 58.4.

    He had me replace a Toro head and adjust another while I was there too.

    For this job I charged a $30 Service call and then $30 and hour.

    Is a 60.4 reading really enough to show a bad wire connection?

  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    Did redoing it fix the situation? You left that out.

    My next step would be to wire up a spare valve to #8, and see if that fixed the problem.

    If it did, rather than monkey with finding the right solinoid for his valve, I'd just change the valve.
  3. AceSprinkleRx

    AceSprinkleRx LawnSite Member
    from Wyoming
    Posts: 95

    Ran the controller through the stations and it came on and shut off while I was there. I told him to give me another call if it failed again over the next few days.

    The valve itself would work when bled manually and the solenoid ohmed out fine. I guess there could be some type of obstruction floating around blocking the port now and then too.

    But would a reading of 60.4 ohms be far enough into the range of bad connections (60-100) to isolate that as a possible cause?

  4. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    After you rewired all the connections, did you test the resistance again to see if there was any difference in the readings?

    Also, Derryberry's readings are a general guide only. 60.0 is not a magical number. Ohms or resistance is affected by several factors including length of run, size of wire, manufacturer of the solenoid. What you are looking for is a reading that is out of line with the others. That was your #8 reading. Not the fact that it was over 60 Ohms, but the fact that it differed from the others,

    Good job on the troubleshooting.

  5. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    Jon - If a solenoid was the culprit, why in the world would you change out a valve? Not that hard to find a solenoid unless the valve is obsolete.

    If you are going to be a repair technician then it is almost a foregone conclusion that you will need to stock a few parts on the truck. A couple R811 solenoids will take care of Irritrol/Richdel, and the old Hardie HR valves, and most of the Nelson valves out there. (It will even fit on the Watermaster valves from HD) A couple RB DV solenoids, and you can take care of the DV and the PGA series (have to remove the adapter) Then a couple Hunter solenoids, a couple Toro solenoids, and a couple Weathermatic M24s and you can take care of most everything out there. Sure there will be the oddball valves but those are not usually the norm, and may have to be replaced or parts ordered. If you are going to be a installation technician that has to do repairs, then I guess the old 'cut and change' is the way to go to keep inventory down.

    A small tool box carried in the truck with these solenoids is a lifesaver. Keep the odd springs, actuators, o-rings, etc. in it and then when the need arises it's right there. And most homeowner's are very relieved to find that it is as simple as replacing a solenoid, rather than a new valve. I've never had one tell me that they would rather me cut out a valve that has been working for 20 yrs and replace it with a new one as opposed to changing out a solenoid. Something about the labor thing I think. Charge them the same price for a solenoid as you do a valve, and they're still money ahead.

    What about a bad diaphragm? If it isn't a DV valve does it get cut out and replaced also?

    Ah well, troubleshooting is a dying art anymore. It never ceases to amaze me when reading the help wanted ads for irrigation service technician. "Wanted, technician to service irrigation systems for our irrigation division. Familiarity with all phases of irrigation, including electrical, hydraulic, and central controls. Ability to use a multimeter, valve locator preferred. Backflow certification a plus. Top wages, up to $15.00/hr. and some benefits. Experience required 1 year." One year! Amazing.

    Just my rant. Don't take it to personally Jon. I just like responding to your posts.

    Jerry R
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,673

    If you're going to run into older brass valves, some of which have 1x32 solenoid threads, as opposed to 3/4x20 threads that the Irritrol valves have, you might want to stock a 'universal' solenoid kit, sold by R Co Parts. Fits nearly any old valve.
  7. AceSprinkleRx

    AceSprinkleRx LawnSite Member
    from Wyoming
    Posts: 95

    Yes, it went from 60.4 down to 58.4. The run of wire might have been around 50'. So I felt my reconnect was much more solid than the original one. Fortunately the owner was there and I showed him the readings from the controller and how #8 was higher than the all of the other "good" stations. Then after the reconnect he saw the reading drop down into line with the rest of the "good" stations.

    We also discussed the possiblity the original installer might have another splice between the valve and controller we aren't aware of.

    Keep in mind I need to start my "education" somewhere and between this forum and the materials purchased from IA, is what's forming my basic foundation. This is what originally prompted this post, my 60.4 reading.

    Derryberry gives a range of readings and what they should uncover. Being .4 over seemed pretty light to me but I didn't want to overlook something the meter was "telling" me. I really figured a bad/partial connection would be higher into the 70's or even 90's. You know, a reading with no doubts about it!

    As always, thanks for your input it helps immensely.

  8. AceSprinkleRx

    AceSprinkleRx LawnSite Member
    from Wyoming
    Posts: 95

    Exactly what I'm looking for, thanks. I know it's possible to supply a rig and spend a bunch of dollars in doing so. What I've attempted to do is to pick up additional parts/heads as I need them to have on hand. We don't have a supply house - or even a good box store here. An Ace with a few Toro/Rb parts is all and not much in way of repair kits, etc. Just heads, valves and boxes. I guess they'd rather sell new than to have a load of inventory in repair parts on their shelves.

    Your post about solenoids will have me putting an order in online very soon. I have no idea what parts are interchangeable yet and how they relate to each other for the simple reason I'm just starting out.

    Do you, or anybody else, know of a good "solenoid repair kit" put together by some online house? Something along the lines of a box with a variety of o-rings, springs, etc. for repairs? Thanks for the solenoid tips.

  9. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    Jerry. 95% of the time, I am doing installs, and my work rig is a old S-10 with a utility body.

    Because of those two factors, its just not an effiecent use of space to carry extra solinoids. If I had a fullsize truck, or a van, it would be a different story.

    I probably do two service calls a week, and 2-3 installs.
  10. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Best install truck I ever worked out of was an Isuzu Pup w/ homemade racks. We had a locking tool box behind the cab and a plywood subfloor over the wheel wells. The area under the sub-floor was divided into 3 areas. The center one being wide enough to slide a plastic crate (old bulb crates) down it. Tools went on one side and scrap pipe on the other. Small part of the sub floor was "missing" back by the tailgate on the tools side so a 5-gallon bucket would fit down in it. We had crates double stacked on the sub floor and sectioned for parts. Company I was working for had a substantial dollar in that inventory. I was down in the DFW area, so I had diaphrams, solenoids and other spare parts for almost everything. From 1" plastic valves to 2" brass moody valves. That truck hauled around 10K in inventory but I billed over 3K a week from it too.

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