2004-09-05

Sprinkler Controller

Looking through the kitchen window this morning, I noticed that the basil in the garden looked a bit wilted. I also noticed that the ground looked rather dry for a day that the sprinkler should have run in the morning.
The first thing I thought was that I, or someone, had turned the sprinkler system off and forgot to turn it back on. So I went to check it in the garage.
I was greeted with the view you see in the picture. The same view I had seen once before. The last time it looked like this was when lightning had taken out the first sprinkler controller. I was not happy.
I wondered if perhaps the wall wart had gone on the Fritz. It felt warm. I unplugged it and plugged it back in. No response from the controller. I checked the fuse, no problem there. I checked the specs on the wall wart. It was 24v AC. That means it was exactly the right supply to drive the sprinkler valves. I jumpered the wires for the garden zone. It turned on. I set a timer in the house so I would remember to turn it off.
This was good news for the wall wart, and bad news for the sprinkler controller. I was sure it was burned out. I started wondering if I could make my own controller from my left over robot parts. I wondered how much it would cost to buy a new controller. Checking online, I found a few under a hundred dollars. So I was not as worried. Under a hundred wasn't too bad. Certainly cheap enough that I didn't have to worry about reinventing the wheel with robot parts.
But first I was going to see if there was anything obviously wrong with the unit that I might be able to fix. I unwired it and took it off the wall in the garage. I started taking it apart. I undid the screws on the back, and prepared to pop off the cover and look at the circuit board. Then I noticed a RJ11 (phone-type) connector on the side. I wondered what it was for, so I looked around online. I saw a few references to a remote control for the system. I also stumbled across the full manual for the sprinkler in PDF format. I was wondering if it listed the pinouts on the RJ11. I read through the manual and hit the troubleshooting section. It said that for a dark display you may have a dead battery and not hooked to the line power. I knew I had it on line power before, so it being a dead battery didn't make sense.
Still, I decided to check the battery anyhow. I did the tongue test. It seemed like a good battery. But I could tell it was the battery that came with the unit a number of years ago. So I got another battery. I plugged it in, at to my surprise, the LCD display turned on! I tried plugging in the wall wart. The AC-power missing icon went off. It seems the unit has to have a good battery or the unit doesn't work. Or perhaps it had glitched and it wasn't until I disconnected all power and put on new power that it was happy. Well, I hooked it back up, and reprogrammed the system. It seems to be fine now.
Whew. I prefer being able to fix it with a little time than having to buy a new unit!

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