January 25, 2017 at 7:59 am #45299
I have a problem with activating my master solenoids that’s defying all my standard troubleshooting. Maybe someone can help me here. I’m using an Opensprinkler DC with a zone extender. I have 2 master solenoids (one from scheme water and one from a tank with pump) and 10 output zones. The tank water is used for 2 zones as it has higher pressure. All this worked fine for ~3 months.
The problem that’s appeared now is that both the master solenoids stopped triggering. All the other solenoids trigger ok, and I can trigger multiple zones at once with no problems. Measuring the voltage at the solenoid shows normal behaviour – a spike in voltage when first triggered before dropping down to the input voltage. I only have a multimeter for debugging, so I can really see how high/long the voltage spike is.
I switched out the power supply (from 9V 1A to 12V 1A) and this resulted in one of the master solenoids usually working (sometimes it will fail).
If I activate the solenoid in isolation, it will work – but not if a target zone is also activated.
If I activate the solenoid when the water is turned off they activate – they only fail when the water is turned on.
I’ve tried running a new (thicker gauge) cable to the solenoid – this made no difference.
If I manually trigger the master solenoid it will keep it open.
I swapped out the solenoid for a new solenoid – this made no difference.
Does anyone have any ideas that I can try?
Leighton.February 5, 2017 at 11:32 pm #45360
I suppose you are using pump start relays for your master zones? If so, do you know the brand name and model number of your pump start relay?February 6, 2017 at 7:56 am #45366
Thanks for the response. I’m not using pump start relays, they’re just standard 24VAC solenoids (the original was a Weathermatic 12000, and when it stopped working I replaced it with a brand new Weathermatic N100 I had spare). One master solenoid is on town water, and the other from a tank which has an automatic pump, so they’re both always pressurised (the pump switches on when it detects a pressure drop).
Leighton HaynesMarch 13, 2017 at 2:58 pm #45549
Do the other solenoid valves work? If so, I assume it has to do with this particular valve (Weathermatic N100). I did find its electric spec online — the inrush and holding currents are on par with standard 24VAC valves (though it’s slightly higher). Do you happen to have a 9VDC or 12VDC power adapter? If so, give that a try (the DC adapter that comes with OpenSPrinkler DC is 7.5VDC), and those can increase the holding current which will hopefully make it work.June 2, 2017 at 8:22 pm #46523
Sorry for the delay, I’ve been busy with other projects, but the winter sprinkler ban just kicked in here so I’ll be looking at this again. I switched over to a 12vdc power supply – this results in one of the master solenoids triggering sometimes, but not reliably enough to depend on. The more distant master solenoid wouldn’t trigger at all (when under water pressure – it works when under no pressure). It’s actually not the holding current that’s the problem – it’s the initial in-rush current. If I turn on the zone, then manually turn on the solenoid (using the manual release), then back off again, the zone will stay on. At 12VDC these solenoids will often trigger even without a higher voltage triggering pulse, so I’m guessing there may be something wrong with the boost circuit – I’ve seen a higher voltage, but maybe there’s not enough stored power in the cap for some reason.
LeightonJune 13, 2017 at 2:04 am #46715
Well, we probably need to get a sample valve (you said its Weathermatic N100, right?) and test it in house to see what’s the issue.
If you have a multimeter, could you measure the resistance of the valve solenoid and post it here? You can measure the resistance between COM (common) wire and the zone wire (particularly any zone that doesn’t work with OSDC). Typical resistance is between 20 to 50 ohm. Perhaps your valve has a resistance that’s quite different, resulting in OSDC not able to operate them properly.June 19, 2017 at 7:02 am #46839
I’ve measured one of the solenoids in isolation, and it reads 35 Ohms resistance. Measured from the terminal blocks they’re between 35 and 38 ohm depending on the cable run lengths. A couple of my normal zones are at about 38 Ohm and trigger reliably, but the master solenoid at 38 ohm doesn’t – presumably because another zone is already active.
After writing that, I pulled it out to have a proper look at it. I noticed the voltage across the main capacitor was just sitting at power supply voltage, which seemed wrong, also I could detect no boost voltage at all. A closer inspection of the board shows that QB2 has blown, and possibly QP2 as well. I’m also measuring dead short across across RP2, but that could be QP2 acting up. My best guess is that RP2 has failed short and blown QB2. QP2 might be ok. I can’t see anything else that’s obviously blown, so I guess I’ll grab a couple of parts and see what that does.
Edit: After desoldering some bits, QP2 and QB2 are both blown.
Leighton…July 22, 2017 at 10:52 am #47211
Let me first briefly explain how OpenSprinkler DC works: it uses an internal boost converter to jump the input voltage up to about 22VDC, and that voltage is charged to a capacitor, which is then directly to the valve to energize the valve (i.e. provides impulse current). The controller then lowers the voltage to input (about 7.5V) to provide holding current. This imitates how the valve behaves under AC current, hence OpenSprinkler DC is able to operate AC valves using DC only voltage.
In theory, whether this works for pump start relay or not depends on the electric spec of pump start relay. But we’ve tested a number of pump start relays on the market and they all seem to work pretty well with the same mechanism. We haven’t tested your particular one and that’s why we need to get one to test in house and see what may be happening. The resistance seems all right so I don’t see any obvious reason why it wouldn’t work. You said QP2 and QB2 are blown? I don’t think this has to do with RP2 — RP2 is a 100K resistor and you would have to apply a very high voltage to actually short that resistor (also resistors generally fail open and not fail short). You can send a support ticket if you suspect some components on the circuit board are blown.
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