Topic: Davis VP2 Rain Gauge Not Working

[FrankP999]

My Davis VP2 rain gauge is not working. I am receiving temp and humidity data. Manually tipping the rain tipper is not picked up by the console.

I am thinking the reed switch has failed. The unit is about 6 years old. I just had to send in my anemometer for repair. Any ideas on the rain gauge problem? Thanks

Frank

[dasman]

Good chance its the reed switch!  Especially if other data transfers.

[PBridges]

If the reed switch is the offending part, how does one go about changing it? Are there any tricks that one should know
about it?
-Bridges

[dalecoy]

Have you checked the connector?  Do you have enough technical expertise to test if the reed switch is working (with a bit of instruction) and some sort of multimeter?  [Or have a friend who does]?

Don't fix it until you know it's really bad.

[FrankP999]

I have a strange bit to add. When I tested by tipping the gauge 10 or 15 times today, nothing was recorded on my Envoy or Console. After about 0.50 inch of heavy rain it started reporting rain. Wierd.

I do have a multi-meter for troubleshooting.

Thanks

Frank

[DanS]

I have a strange bit to add. When I tested by tipping the gauge 10 or 15 times today, nothing was recorded on my Envoy or Console. After about 0.50 inch of heavy rain it started reporting rain. Wierd.

I do have a multi-meter for troubleshooting.

Thanks

Frank

A connection, outside the gauge or inside, got wet and started conducting? I'd closely check your connections for tarnishing, oxidizing, and weather proofing first.

[dalecoy]

I have a strange bit to add. When I tested by tipping the gauge 10 or 15 times today, nothing was recorded on my Envoy or Console. After about 0.50 inch of heavy rain it started reporting rain. Wierd.

I do have a multi-meter for troubleshooting.

Thanks

Frank

Not weird at all. 

As I recall, the connection from the reed switch ends in an RJ-11 (telephone) connector.  The switch is connected to the red-green pair - which are the center two wires in the cable.  You can get (Radio Shack) a matching wall-mount connector that will make connecting your multimeter easier. 

I do not recommend trying to attach your multimeter directly to the reed switch.  Please don't do that.

If the multimeter has a "continuity" beeper, use that setting.  Otherwise, set it on any ohms setting.  When you tip the buckets, there should be a momentary connection as the assembly rotates past level. 

OK, now that you've demonstrated that the reed switch is OK, clean up the connectors, and plug it back together.  Watch out for spiders!

[SLOweather]

If the reed switch is the offending part, how does one go about changing it? Are there any tricks that one should know
about it?
-Bridges

I don't recommend it, except as a last resort. It's small and made of glass and fairly delicate. There seems to be a relationship between the switch, the orientation of its vanes (|| vs =) and end-to-end vs the magnet polarity. And, re: a post I just made in the calibration thread, the distance between the magnet and the switch as determined by bushing wear.

Still, if you wanna tackle it, you can find the same sized switch inside wired window alarm mag switches. Break it out carefully, unsolder it, and solder it in the tipper assembly in place of the old one.

[RainmanWeather]

I'll have to weigh in on this one, I just replaced the reed switch on my 7yr old Vantage Pro. I found mine had been acting up kind of like you are experiencing, then all of a sudden I started getting 25" downpours on sunny days! looking it over there was small amount of corosion but nothing serious.. I really think the switch plain went out, but maybe the connection was going bad too (as may be on yours).

So here is how the replacement went for me:

You can get the replacement direct from Davis fairly reasonably priced ($2): http://davisnet.com/weather/products/weather_product.asp?pnum=07120.031.

Observations: the reed swx is in a "cradle" under the tipping bucket and held in place with a small plastic cover. I pried the cover off it up on the roof because I didn't feel like taking the whole thing down. Release the cable from the ISS, loosen up the radiation shield and snake the attached cable on up through the access hole and it's free. Then I brought it down to the workbench and got the old man glasses out. The reed switch has a little bump on one end (smaller) take note of how that is oriented and the correct end of the wire. I also noted the position of the reed itself inside the casing, flat side up and could distinguish what was top vs bottom on the original. Then it was just a case of heating up the old solder to release the old switch and carefully re-soldering the cables to the new one ensuring the exact same positioning as the original.

A couple of notes, the replacement has much longer ends than the installed one, I of course gave a little more room on each end to make it easier.. wrong. back up on the roof and back down, re-soldered one more time with appropriately short ends so it would fit back in the cradle correctly! also the cable is just kind of "spot" soldered on the leads, pretty difficult to do. I gave the cable ends a twist around the sensor leads to hold in place and hopefully give a better bond soldered. back to the roof, put it back in the cradle, snap the cover back in place, bring the cable back through the shield and back into the ISS. Easy as Pie!

Works perfectly now. Wife just reported .46 on the CoCoRaHS, and I see .43 on the station.. hmm I may have to double-check her manual reading!