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In one of the videos about OpenSprinkler, Ray suggests that the transformer that powers OpenSprinkler be plugged into a surge protector. While that makes a lot of sense to me, there isn’t room for a normal surge protector in the box that I installed the controller in.
I haven’t installed the MOVs (that I ordered with the controller) across the solenoid drivers yet, and I was wondering if it makes any sense to install one of the MOVs across the AC input pins (on the back side of the board, with the hope that it will swamp out any transients that happen to get through the transformer?
If those MOVs aren’t suitable for that location, is there another part, or small device that would provide the surge protection?Yes you can solder an MOV across the AC input pins and that should provide protection to transient voltages. Just make sure the exposed leads of the MOV don’t touch other parts (use an electric tape to cover the area underneath the MOV).
I have hardware 1.4u and firmware 1.8.3. OP works ok when I uncheck sequential (never crashes). When I check sequential, the controller crashes when 2 valves are open at the same time. This happens intermittently. The crash is not when the valves open or close but during a 15 minute irrigation period. Does a MOV fix this? I don’t know what a MOV is. Do I need to modify my board to be like 1.42u to eliminate the crashing (screen goes blank, no access to OP via chrome and a reboot restores normal function.)
MOVs will not help your crash. MOVs are useful only on power surges. For projects like OpenSprinkler, they help mainly during electric storms. Lightning strikes on the earth can send large currents through the ground for long distances. The large ground currents will induce voltage spikes in wires buried in the ground. Since the sprinkler valve wires are most often buried, this brings the voltage spikes right back into OpenSprinkler. The MOVs help dissipate these voltage spikes before they damage OpenSprinkler.
I suspect that your problem is that your 24V power supply is undersized for the current draw of your sprinkler valves. With only one valve on, the 24V power supply is OK. With two valves on the 24V power supply is marginal. As the 24V transformer heats up, its output voltage drops and when it gets too low, OpenSprinkler crashes. I would monitor the +5V on the OpenSprinkler and then activate two valves watch the voltage value and then touch the transformer to see if it is getting hot. My guess is that the transformer will start to get hot and the +5V will start to droop. If you find that the above it true, then get the current rating of a single sprinkler valve. You have to check with your manufacturer, as they vary widely. Then your 24V transformer should be rated at 2.5 times the rating of a single valve. The extra 0.5 is for current used by OpenSprinkler and saftey margin. If the 24V transformer appears to be sized OK, then something in your system is out of spec. If you have a AC ammeter setting on your multimeter, then you can check if a valve with too high a current draw or whether the 24V transformer is not putting out its rated value.
@COsgood: if you have two valves open at the same time when sequential is checked, I assume it’s either because one is a master valve, or is defective and cannot close once opened. in the latter case, the defective valve (most likely shorting) will start drawing too much current that causes the voltage from the 24VAC transformer to significantly drop, hence the controller crashes.
As mrburns42 said, adding MOV would not help in this case because the problem is not caused by power surge.
I built mine last WE and installed it and seem to have had the same problem as COsgood this week.
I have the same rev board and FW, 3 stations and a master valve. I have them setup to run sequentially from 7am for 10min each.
The first couple of days it cut out on the second station and just displays a blank screen and then the last couple of days it has been cutting out on the first station.
I am going to try taking off sequential for tomorrow and see if it is OK as COsgood suggested.
I have brought it inside tonight to test without valves (no wifi or cat5 to the garage yet) and it runs through a test run-once program of the same length OK.
The transformer is the same one I ran on the old controller with the same configuration. It is 24VAC 1A(although runs at 28V).
I will do some more trouble shooting over the WE and may even see if I have the same result with the previous FW version.
Cheers,
Craig@mrburns42 wrote:
MOVs will not help your crash. MOVs are useful only on power surges. For projects like OpenSprinkler, they help mainly during electric storms. Lightning strikes on the earth can send large currents through the ground for long distances. The large ground currents will induce voltage spikes in wires buried in the ground. Since the sprinkler valve wires are most often buried, this brings the voltage spikes right back into OpenSprinkler. The MOVs help dissipate these voltage spikes before they damage OpenSprinkler.
I suspect that your problem is that your 24V power supply is undersized for the current draw of your sprinkler valves. With only one valve on, the 24V power supply is OK. With two valves on the 24V power supply is marginal. As the 24V transformer heats up, its output voltage drops and when it gets too low, OpenSprinkler crashes. I would monitor the +5V on the OpenSprinkler and then activate two valves watch the voltage value and then touch the transformer to see if it is getting hot. My guess is that the transformer will start to get hot and the +5V will start to droop. If you find that the above it true, then get the current rating of a single sprinkler valve. You have to check with your manufacturer, as they vary widely. Then your 24V transformer should be rated at 2.5 times the rating of a single valve. The extra 0.5 is for current used by OpenSprinkler and saftey margin. If the 24V transformer appears to be sized OK, then something in your system is out of spec. If you have a AC ammeter setting on your multimeter, then you can check if a valve with too high a current draw or whether the 24V transformer is not putting out its rated value.
Ray, I continue to have the problem as originally described. When sequential is NOT checked and 2 or more valves open a the same time, as intended, a crash will occur after the valves are open several minutes. (as if something is heating up) When sequential is checked and one valve is opened at a time, there are no problems.
What is new is that my neighbor bought an OP (actually he bought 2 with 2 expansion boards). His name is Gafner if you want to check his purchase. I substituted his OP for mine. Same power supply, same valves, same everything. I used my expansion board and his expansion board and both ran ok. I can run sequential un checked on his OP with no problem (with either expansion board, his or mine). I can open 3 valves a the same time. It never fails. I put my OP back in use and it fails when 2 valves are opened at the same time. I believe my OP is defective. It’s very important that I be able to run with 2 valves opened at the same time. What do you suggest?
More information on crash problem when sequential is unchecked: Problem occurs with any 2 valves are opened at the same time. Time to failure when I attempt to open 2 valves at the same time is between 50 and 120 seconds. Screen goes blank. Upon off/on cycle, OP starts up normally. Opening 1 valve at a time continues to work ok.
@COsgood: the issue you encountered is probably a hardware problem. Here are two things to check: 1) is your sprinkler transformer rated at least 500mA output current? If the current rating is too low, you will have trouble turning 2 valves on at the same time; 2) does your controller have a yellow, disc-shaped PTC fuse? If so, consider soldering a wire across it to bypass the fuse. I’ve received reports that when the ambient temperature is high, the PTC fuse is likely to be triggered, causing the controller to freeze. Having 2 valves open at the same time will increase the chance of this happening. Shorting out the fuse will solve this problem.
@Ray That fixed the problem. I can open at least 3 valves at the same time. No crashes. Thank you. What is the consequence of a jumper on this fuse?
The limitation of jumpering the Poly Fuse is that now the only thing protecting you from an overcurrent condition is the internal fuse link within the 24V AC step-down transformer. These fuse links are non-replaceable. So when they blow , you have to change the entire transformer.
The causes of overcurrent conditions are typically either bad solenoids on the water valves or short-circuits in the interconnect wiring from the controller to the valves. Typically, this effects only one zone. Therefore, the symptom is that one day nothing works and you find no 24V AC input to the controller. Now, the 24V transformer could also be damaged by a lightning strike or power surge, so you replace the transformer. Everything appears to work for a day or so until you turn on the problem zone, then the transformer dies again. Each new transformer is going to cost you $15 to $25 bucks.
Again, you will only have this problem if your system develops a defect that causes an overcurrent condition. If you want to help reduce the cost of such overcurrent conditions then you can add an inline fuse holder and fuse. Typical over-rating on the fuse is at least 20% over the specified output. Therefore, if the transformer is rated at 750mA, I would suggest starting with a 1A fuse minimum. In-line fuse holders can be found at many auto parts stores, big box department stores, etc.
If you have a properly sized in-line fuse, then should you develop an overcurrent condition, the cost of repair is replacing a 50 cent fuse, not the entire transformer. Of course, you still have to locate and repair the short, but the cost of troubleshooting goes way down.
I have the same problem of my controller (hardware version 1.4s and firmware version 1.8.2) freezing/crashing every few days. It has happened once during a sprinkler cycle (causing a circuit to run all night) but usually happens at random times with no valves open at all. I have shorted the legs of the PTC fuse as suggested above to no avail. What else could cause a controller freeze?
The other possibility I can think of (that has to do with crashing) is the DS1307 RTC and / or 32.768kHz crystal. I suggest replacing these two and try again. If you don’t have a hot air gun to replace DS1307 RTC, please send an email to [email protected] and we will arrange for a repair for you.
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