Weird Technical Issue

So we put in a new irrigation system in the backyard a few months ago. I installed this timer, and it was working fine. But a few days ago, we realized that the sprinklers were no longer coming on.

Instead of waiting for the anointed time, I started them manually (that is, I pushed the “Manual” button that starts the sprinkler sequence). It started up, and started flashing the thirty-minute notification, then twenty nine, for the first station. But the valve didn’t open.

So I put a voltmeter on the timer terminals for it, and it read zero. Which of course explained why the solenoid wasn’t engaging. I finally concluded that the timer was no longer functioning properly, and since it cost less than thirty bucks, I just went to Home Depot to get a replacement.

After installing and programming the new one, I tried it again. Exactly the same result. It acts like its running the zone, but there is no voltage at the corresponding terminal. I sent an email to Orbit to see if they had any ideas, but haven’t gotten a response. I’ve followed the instructions to the letter. Does anyone have any ideas that I’m missing somehow?

[Afternoon update]

After being on hold for half an hour, I finally talked to someone at Orbit. I explained the problem, and all that I’d done, and she said, “Wow, that’s weird.”

They’re going to ship me two more in case one of them is bad. So it’s good customer service, at least. So I could set up a store to sell timers that don’t work.

[Update a few minutes later]

I should add that I didn’t tell the whole story. When I went to Home Depot to get the replacement, it turned out to be open box when I got it home, and it was dead. So I had to go back to get another one that hadn’t been opened, and that’s the one that acted like the first one, with no voltage output. So if I get the next two I’ll have five of the things, but I plan to return them. If the ones I get work, I might even return the second one they send, for store credit.

23 thoughts on “Weird Technical Issue”

  1. Did you try a different wall transformer, or did you use the old one with the new timer? If the transformer outputs a separate voltage for the logic circuitry versus 24 VDC output power, the fault could be the power supply.

    Some types of DC outputs might require a load (open collector, etc). I couldn’t find the detailed electrical specs to see if common was +24 or DC return (source vs sinking outputs).

    In case the output turns out to be good but the valve still doesn’t work, check the resistance on the solenoid to make sure it reads a few ohms, in case the coil is open or shorted. Also make sure the DC common is good, in case the solenoid is floating.

    I couldn’t find the full manual for the 57594 online, but here’s a link to the 57894 manual, which is probably similar.

    In the troubleshooting section they say, under ‘valve not working’, they say “3. Flow control stem screwed down, shutting valve off.”

    From elsewhere, check the solenoid:

    1. Check to see if the valve can be turned on and off with the solenoid. This is the black cylindrical object on top of the valve with wires coming out of it and will have directional arrows with on and off printed on the base if it can be used to control the valve. Otherwise, the bleed screw can be used to activate the valve. This is a plastic screw head 1/4 to 3/8 inch in diameter located below the solenoid.

    2. Turn the solenoid or bleed screw a quarter to half turn in a counterclockwise direction to open the valve.

    3. Turn the solenoid or bleed screw the other way to close the valve, tightening only until snug.

    But probably the most common reason for sprinkler valve failure is that California’s electric grids are down again, so you might want to check that, too.

    1. Replaced the power supply, too. No joy. It doesn’t work on any of the stations, so it’s not the solenoid. I can turn the valve(s) on manually by rotating the solenoid counterclockwise. But there is no voltage on the solenoid terminals on the timer.

      1. Hrm…

        *searches the Internets*

        A schematic for a different Orbit timer unit!

        It has a fuse… but that probably kills the whole unit. But it also has what looks to be thyristors (SCR family?) as the output device (in the last image). It’s hard for me to tell because the text is so tiny.

        Does anyone here recall if those are quirky about checking open circuit voltage? Do they need a small load? I haven’t dealt with one in quite a while.

      1. But with Wifi, the local water authority could come by, hack your sprinkler system from their truck, and issue you a big fat fine during a drought. What’s not to like?

  2. Well, I might try putting 24V and .25 amps right on the command and the wire out to the solenoid and seeing if that will turn it on. (My voltage/amps are guesses, but I think that’s pretty standard for sprinkler systems.) (I’m also not sure what the easiest way to get a 24v power supply is without just buying one or having one of those handy bench power supplies on hand. Maybe the power supply that came with it has the right output?) No voltage at all at the controller makes me wonder if there’s a short out there somewhere in the system and it’s cooking the controller somehow, both the old and now the new. But you’d think it would be protected against that sort of thing? And there would probably be a pop and some magic smoke. . .

    I guess you could check the resistance as well; IANA electrician, but low resistance could be a short, high resistance a break in the wire or another issue. But with no voltage at the controller, I don’t know; kind of spooky. Good luck!

  3. Had exactly the same problem 1.5 years ago with exactly that controller and did exactly what you did, measure the voltage and got 0V. Also never got a response from Orbit

    Try measuring the voltage at exactly the moment the timer is supposed to activate the solenoid. I think you’ll see a 5 second 0-24-0V square wave. Your volt meter should have enough time to see it. I never got an official explanation from Orbit or anywhere else but here’s what I think is going on. The controller expects the solenoid to open and then the water pressure is supposed to keep it open. The problem isn’t the solenoid it’s how tightly the solenoid is squeezed against the seal, the water pressure can’t get it open or hold it open. I ended up replacing all of the valve guts since I had a couple of old valves in the garage and it worked. BTW, you can sit at your coffee table inside with the timer and a solenoid to see it happening which is what I did after many frustrating other tests.

    1. Oh, so the voltage is only transient? That didn’t occur to me. It didn’t occur to her, either. But it still seems strange that it doesn’t work with any of the zones. The valves are all the same vintage as the timer (a few months), so it seems unlikely that they’d all fail at once.

      But if that’s the case, how does the timer close the valve? And even if it’s a problem with the valve, I’d at least hear a click as the solenoid attempted to open it. But the valves are right next to the box, and there is no indication that the timer is attempting to open them.

      1. They are likely to be pilot-operated solenoid valves, where they don’t even really cycle without some water pressure. The solenoid just moves a tiny valve, and that valve controls the big valve. The other thing all your valves have in common is the water supply pressure, without which, all of the pilot-operated valves probably won’t work. It could be that someone doesn’t have a spigot turned all the way on. Essentially, “Is it plugged in?”

        As I recall, one of the Apollo program engineering directors, while working on the Space Shuttle design, realized that if they’d used pilot-operated solenoid valves on Apollo’s RCS system, they could’ve shaved a hundred or so pounds off it.

        And yes, there’s plenty of water pressure on them; when I turn the solenoid manually, the zone turns on, at good pressure.

  4. Um stupid but did you try the Multimeter set to AC. George schematic has it taking AC in and the Output is connected to VDD, with the gate control from the MCU. I don’t see any clipping or rectifier between the AC in and the VDD.

        1. Just to beat a dead horse read the overview on the homedepot site you linked.

          Output: 24 VAC
          Input: 120 VAC (external transformer)

          Try AC.

          1. The schematic I linked is for a slightly different model from Orbit, I think some kind of remote unit, but I figured it would have quite a bit of commonality with the one he has.

          2. Bingo. The tipoff is the “external transformer”, which indicates that it is merely a step-down transformer and not a DC power supply. The timer most likely has its own internal rectifier circuit. This unit is for 24VAC solenoids. If Rand has 24VDC solenoids, he has 2 choices: rectify the output while keeping track of polarity, or get a compatible timer unit that produces 24VDC. I worked in a lab with about 45 pneumatic solenoid valves and these were 115VAC. Wiring was simple and I didn’t need a power supply. The downside was that I had to warn my coworker to turn off the power to the SCR bank when doing any maintenance work. He was used to 24VDC and would get an unpleasant surprise if he just grabbed naked wires as he was used to being able to do.

          3. Good catch! In the schematic I linked, the outputs are fed by VDD and VDD is 24 VAC. That would explain why they weren’t using regular transistor outputs.

            So Rand needs to flip his meter to AC and repeat the tests.

          4. Need to work on my English George. Think that what I been saying. Maybe a bit more snarky in the replies 😉

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