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No rain in Cumbria!

Posted: Mon 28 Nov 2011 3:20 pm
by cancunia
We all know that's just not possible, so something must be wrong with my station. The wind speed, direction, temparature etc are all ok, so I'm hoping that someone has some ideas of what else might be wrong. I checked the tipper, all is fine and the contacts at the end of the cable on the connector show that the reed valve is working, I get about 2 ohms when the magnet on the tipper lines up with the reed valve.

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 3:23 pm
by mcrossley
Does it count if you manually tip it whilst connected to the transmitter?

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 6:26 pm
by cancunia
Sorry, I should have mentioned that I tried that. Answer is, not so far as I can tell. I moved it a few times up and down, but may have done so too quickly for it to count. There was quite a lot of rain over the past few days, and as nothing was obviously wrong, I'd have expected it to register.

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 8:12 pm
by Truscom
Hi,
I have moved my new station recently without disconnecting the rain sensor and it registered rainfall left right and centre! A previous post on this site, which I have read after, does mention about theneed to disconnect sensors before moving etc... I would say your rain gauge is faulty?
Martin.

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 8:23 pm
by AllyCat
Hi,

What is the resistance when the reed switch is open? Could there be water in the cable/connector? The transmitter unit delivers only about 10 uA to the reed and the detection threshold is about 1.5 volts so the leakage resistance must be well over 100k ohms. Can you measure the voltage across the connector pins (the middle two)?

Occasionally I've encountered "missing" rain tips but couldn't identify a definite cause. I think it was a badly aligned connector contact (I was using an extension cable) but sometimes did wonder if it was a processor "lockup" (in which case remove and replace batteries in both units to fix it). However, tipping the see-saw too fast is NOT the problem. There doesn't appear to be any filtering and I think I managed to get it to accept over 100 (simulated) tips in a second!

Cheers, Alan.

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 9:21 pm
by Tau Bootis
Hi

I have just sorted a similar problem with my anermometer, I was getting resistance as it rotated but it still didn't work, the cause was damp and lots of dead fleas on the circuit board where the reed switch is. I also broke the reed switch so be very carfull when cleaning it.
If that is clean and dry then it coud be at the other end in the sender unit, mine looked a bit ropey before I cleaned it up, that unit is glued and so I used a Stanley knife to get it apart.

Re: No rain in Cumbria!

Posted: Mon 28 Nov 2011 9:42 pm
by cancunia
Thanks for all of the tips, I think from a couple of them the problem might well be that I've moved the sensors to a different location and not removed / re-inserted the batteries. The unit was new in August and the problem did happen until after the move this weekend, so next time I get a chance I'll swap the batteries out. I've bought some Lithium AA's from fleabay and will try them when they arrive.