OpenSprinkler 3.0 DC low output voltage

[vagrant]

Hi All,

I’ve just installed a new OS 3.0 with an AU 240V -> 12V DC 1200mA power supply.

After a lot of digging and pipes and a certain amount of cursing for good luck, I’ve tied in my valve control wires and hit run on my test program and…. nothing.

I’ve done a bit of troubleshooting, replacing the solenoid wires with a multimeter, and can see 3.5-5V coming out of VIN but only 0.02V AC on the active stations (nothing on inactive stations). This seems to be the same for two power supplies of the same rating.

I don’t know enough to tell where the fault lies – input, config, device?

Any suggestions before I tear my hair out?

Chris

[Ray]

Since you have DC-powered OpenSprinkler, please note that you should only measure DC voltage and DC current — because the controller outputs DC-only voltage. So “0.02V AC” doesn’t mean anything because the controller does NOT output AC voltage.

VIN always outputs 5V — the VIN pin is for powering certain sensors, NOT for solenoids. You should be using the COM (common) pin, as the user manual clearly states. So each solenoid should have one wire that goes to the COM, and the other wire goes to an individual zone port.

Also, VIN is NOT (I repeat: NOT) for input voltage — as the user manual clearly state, the input power should be supplied through the black-colored power barrel. I’ve seen at least one case where the user tried to feed 12V to VIN, that caused damage to the controller.

The way DC-powered controller works is by generating a high impulse voltage to energize the solenoid, then lower it to input voltage to provide holding current. When you use 12VDC input supply, that means after a zone is turned on, at stable state, the voltage measured between COM and that zone should be roughly 11VDC (a bit lower than 12VDC).

[vagrant]

Thanks for the quick reply Ray.

My setup is as you describe.

I wasn’t very clear on my testing, sorry.

DC input is through the barrel connector.
OS boots and runs happily, web interface has no issues. I’ve programmed and run sample stations. LCD displays active stations correctly.

All measurements have been taken by connecting multimeter ground to common, and sensor (red) lead to a wire secured in the station output.

VIN is working – confirming at least that some power is being output and my common OS common terminal is connected. I’m looking for user error here and this helped confirm I’d got wires in the terminals successfully.

Ah, I was originally measuring DC from the station outputs and it was so low I thought I must have it wrong. Voltage is well under 1V either way, so low it was difficult to get any reading. But I confirmed a small pulse on both master and the active station.

Any other tips to help troubleshoot?

Cheers,
Chris

[Ray]

First, disconnects the solenoids wires from the controller (you can simply remove the common wire, which effectively disconnects the solenoids from the circuit). Make sure the solenoids are the correct type, this can be done by measuring the resistance from the common wire to each zone wire. The resistance should be somewhere between 20 to 50 ohm. If it’s too small, your solenoids may be of ‘latching’ type, which is not compatible with DC-powered OpenSprinkler.

Next, with the solenoids disconnected, and the controller powered on, measure voltage from VIN to GND, this should be 5V. Earlier you said it’s between 3.5V to 5V. If it’s noticeably below 5V, something is wrong — it should be a fairly stable 5V.

Then, turn on a zone (e.g. zone 1), and measure voltage from COM to that zone. This should be slightly before your input voltage. For example, if you use 12V DC power supply, this voltage should be maybe 10 to 11V. It’s important that the solenoids are disconnected when you measure this voltage, otherwise, if the solenoids have a shorting, or are of the wrong type, it would interfere with the voltage measurement.

[vagrant]

Hi Ray,

These are pretty much what my initial troubleshooting steps were – to completely disconnect the valves and test only the output on the controller.

I’ve retested the VIN voltage, and I was mistaken: It’s fairly stable in the 4.5-4.9V range. Must have been my shaky hands causing the 3.5-5V that I initially reported.

For each zone, though there is definitely something happening, it’s barely registering on my multimeter (back on DC voltage!). Your comment that the voltage will drop after the initial operation made me go back and recheck it incase I was too slow testing the zone output, but by my research that’s still going to be above 5V and not in the mV ranges I’m seeing.

So, still a problem with output voltage on the zones.. any other suggestions?

That being said, I’ve had a look at the solenoids and I’m pretty sure they ARE a latching type. I’m seeing ~40ohm resistance when measured from the end of the control wires (at the controller, which is ~20m from the solenoid) but they are Irritrol 2400MT. I was sure I checked this before I ordered the parts but obviously got it wrong anyway. Looks like I’m in for another unit!

Cheers,
Chris

[vagrant]

Actually, I’m less convinced that the solenoids are latching – although the spec is silent on “non-latching” I see that you can buy the DC latching version as a more expensive option, which I don’t think I paid for. More investigation required.

[Ray]

As I said, a resistance in the range of 20 to 50 ohm is normal. Since you measured 40 ohm, it is ok and it shows your solenoid is NOT latching type (i.e. your solenoid is non-latching type). At any rate, as I suggested, you should measure voltages after solenoids are disconnected — so the resistance of the solenoids doesn’t matter in that case. When a zone is turned on, the voltage between COM to that zone port should be slightly lower than the input voltage. If not, I suggest that you submit a support ticket — a zone, when turned on, should output the input voltage minus a couple of volts; if not, I can’t explain it, and it’s best if you send it back to us for checking.

[Author]

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