Hi
All sorted; this is what I did:
I took my anemometer and direction indicator apart…OMG they were both full of damp and dead fleas; I had to clean the direction indicator in situ
and by the time I’d finished it was dark and raining; during my heavy handed clean up operation I managed to break the reed switch in the anemometer
they are so fragile.
I found some reed switches on Ebay; 10 for £2.95 incl. p&p that’s not bad considering I almost bought 2 for £5.97 from Maplin.
They arrived yesterday and I set about replacing the broken one, one thing I noticed was that the flat contacts within the switch were at 45° to the horizontal this is to ensure that the switch operates when the magnet passes on each side, I’m not sure whether it was supposed to have been at 90° but as it worked at 45° that was how I intended to fit the new one.
These are fiddly to solder without cracking the glass or buckling the contacts, so on my first attempt the orientation was wrong and I only achieved one contact per revolution, so I de-soldered one end and carefully twisted the switch to 45° and re-soldered it; now it switches twice per rev. Indecently you can actually hear the switch operating as the anemometer turns.
The anemometer bearing seemed to be as good as new but the wind direction bearing felt a little dry, so I gave them both a bit of 3 in 1.
My station is almost 2 years old now and judging by the state of the internals I think a 12 to 18 month service would go a long way to keeping them in good working order, just remember to be extra careful of those reed switches!
I think the reason all the fleas were dead is because I had sealed them in by blocking the RJ11 socket with Vaseline back in August when the problem first appeared. I have now tried to seal all gaps and cracks with grease to prevent the ingress of moisture and insects.
I checked the rain gauge and apart from some dirt in the buckets it was fine.
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). So you should see an open circuit and pulses of low resistance, if the sensor is spinning your meter will probably integrate the resistance over time, so you need to pull the sensor down and slowly rotate it to find the true resistance being seen by the transmitter.