Comment on help needed to understand this diagram of a water flow sensor (from a boiler)
diyrebel@lemmy.dbzer0.com 3 weeks agoYeah, if by /in system/ you mean connected to the board. I didn’t mess with anything other than to stick my probes onto the wires. The boiler is not switching on to heat water and it acts just as if it is not detecting that water is running. So a broken flow sensor was one of the theories. And since the readings seem quite off from what’s expected I guess buying a new sensor is the right move.
Once I get it removed I’ll see if it looks like I can rebuild it but I don’t expect that to go well. I may not have to waste it though. Considering the at rest voltage is double the running water voltage, it’s still detecting water running. It’s just not giving the right voltage. So one idea is maybe I can repurpose this to turn on a shower light when the shower water is running.
If I had an electronics background I would probably try to do a makeshift gadget that converts 0.66 V to 2V and 1.33 V to 0 V. Then I wouldn’t need a new sensor (which could cost €100… i’ve not checked locally yet but online prices are looking terrible).
tofubl@discuss.tchncs.de 3 weeks ago
With better tools, it would be easier to troubleshoot more precisely. An oscilloscope would help you understand what’s going on, for example.
From what you describe, I’m actually starting to suspect the other end (the controller?) to be the problem.
One idea you could try before buying anything is to disconnect the sensor, supply it with 5V and ground (double check with data sheet!) and see what’s happening on the output when there is flow. If you don’t measure anything, as I would expect since the pin alternates between a floating state and ground, you then add a 10k or 50k ohms pullup resistor between 5v and output and measure again, and should get the levels you expected to see in the first place.
Don’t know if you’re comfortable doing this, but maybe you can find somebody to help you out?
diyrebel@lemmy.dbzer0.com 3 weeks ago
It shows 5V on the diagram but I don’t think that’s precise. I measured the red wire at 4.68v which is around what the guy in the video got in his test. Since the board is part of the circuit I suppose I cannot rule out the board as a problem. Testing the sensor in isolation will be rough going because it’s a proprietary joint. So I would have to get a tight rubber hose and fit that onto a garden hose. For powering it I have a switchable ac adapter with a 4.5 V setting. Or I can maybe get 5V off a USB charger or ATX PSU from a PC. My multimeter does not have a frequency function but I can see from the video that it would be useful for this so I might look for 2nd hand multimeter at the next street market, though that will set me back a week (OTOH might be worth it if it helps diagnose this in a way that helps avoid buying the wrong part).
tofubl@discuss.tchncs.de 3 weeks ago
5V or 4.68V input isn’t meaningful. The sensor has some input range and 4.68V most definitely falls into that. Could be a design choice that has no real implications.
On the other hand, if the device normally supplies 5V, just yours doesn’t, then that’s further evidence you have a faulty controller.
tofubl@discuss.tchncs.de 3 weeks ago
My money is on faulty controller at this point, but I think you’ll need to find someone with electronics chops if you want to avoid just buying parts until it works again.
For what it’s worth, I didn’t mean take the sensor out of the wall, but just electrically unplug it from the controller to see what it does on its own when you turn on the water.
diyrebel@lemmy.dbzer0.com 3 weeks ago
Yeah I figured that but the terminals on the sensor are hard to reach so I was figuring I would need to remove it. But then it occurred to me that I could leave the thing in place and do the isolated test by unplugging the X2 connector from the motherboard and easily access the pins through that connector. So that’s what I did. Results:
So in isolation the sensor worked correctly. Then I plugged it back into the motherboard and retested to confirm again the bad voltages. But in fact the readings were correct. It’s unclear why it works now. I wonder if the unplugging and replugging of the x2 connector improved a connection that deteriorated somehow.
Thanks for saving me €36! However incidental. If I had not done the test in isolation, I probably would not have messed with the X2 connector. I would have normally just replaced the sensor as an experiment.
diyrebel@lemmy.dbzer0.com 3 weeks ago
It shows 5V on the diagram but I don’t think that’s precise. I measured the red wire at 4.68v which is around what the guy in the video got in his test. Since the board is part of the circuit I suppose I cannot rule out the board as a problem. Testing the sensor in isolation will be rough going because it’s a proprietary joint. So I would have to get a tight rubber hose and fit that onto a garden hose. For powering it I have a switchable ac adapter with a 4.5 V setting. Or I can maybe get 5V off a USB charger or ATX PSU from a PC. My multimeter does not have a frequency function but I can see from the video that it would be useful for this so I might look for 2nd hand multimeter at the next street market, though that will set me back a week (OTOH might be worth it if it helps diagnose this in a way that helps avoid buying the wrong part).
tofubl@discuss.tchncs.de 3 weeks ago
Oh and be careful if you do end up trying it.
There’s no safety risk in what I described, but reversing the power supply might very well fry the device.