Topic: "Zapped" Relative Humidity Sensor or SIM? RESOLVED

[LFWX]

It seems my Relative Humidity Sensor is dying. (got zapped?)
I'll be disassembling the Radiation Shield to do my annual cleaning ASAP.
Is there something I should look for on the sensor that could give some indication of the problem and/or be corrected by myself.

The trouble started a few days ago. It appears to have started after we had two power outages on 7/31/11 (I have the cabled version of the VP2), so I'm suspecting a power surge to the SIM and/or Humidity Sensor. The main console is plugged into a surge protector, but the extra console (not supplying power to the SIM) is not.
As you can see below, my relative humidity drops late in the day and then returns to normal sometime in the afternoon.

My station vs. stations within 11 miles. (no trouble seeing which station is mine starting on 8/1/11)
7/27/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110728&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
7/29/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110730&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
7/30/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110731&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
7/31/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110801&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
8/1/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110802&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
8/2/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110803&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176
8/3/11 http://weather.gladstonefamily.net/qchart/D1039?date=20110804&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176

I did try removing power from the SIM this morning and checked the connections for contaminates, but it didn't seem to change anything. I may try disconnecting it for a longer time this evening.
The SIM is only 59 days old, but the Humidity Sensor is the original (activated December 2007).

Assuming I don't find something on the sensor acting as a desiccant, does anyone have any suggestions before I call Davis to have them send a new sensor?

[DanS]

" does anyone have any suggestions before I call Davis to have them send a new sensor? "

You could check the actual temp/humidity sensor chip for anything obvious on it or in the tiny air passage.
Just don't stick anything in the air passage way or you may damage it. If you see anything, spider  web, dirt, etc., you could use canned air to try and get it out. Davis was smart placing the screen cover over it so chances are small there's anything in/on it and something else (like you mentioned, maybe electrical) causing the problem.

[Aardvark]

I had to have mine replaced.  I contacted Davis, they sent out right away a new sensor.  I was getting the ---- for the temp and humidity for a long period and contacted them.  seemed to happen right after a driving rain.   I found out that the sensor which sits at the bottom of the radiation shield was getting soaked by water collecting in that location and that was damaging it.  So I had them send one out, I had to flip the unit up on spacers so that the sensor faced down about a fraction off the bottom shield.

Now they sent me one and I paid 82 dollars for it, sent the other unit back and we are good right now. I have a Fars  so mine is mounted upside down and off the bottom.  IF you have the standard shield, then the unit is mounted to a plate that you afix to the top of the chamber.

I had to order a replacement soil station, and got the best price from Archer Trading post.  They have both versions at a very reasonable price.  Here are the URLS:

http://www.archertradingpost.com/atp/index.php?main_page=product_info&cPath=1_6_9&products_id=94

http://www.archertradingpost.com/atp/index.php?main_page=product_info&products_id=89


I am  betting yours  got flooded  as  did mine and stuff shorted out

[LFWX]

Well, I didn't find anything unusual while cleaning the station today. Tried some compressed air anyway. Now that the sun has set, the humidity has started dropping when it should be rising, guess I'll be calling Davis in the morning.

[Aardvark]

Well, I didn't find anything unusual while cleaning the station today. Tried some compressed air anyway. Now that the sun has set, the humidity has started dropping when it should be rising, guess I'll be calling Davis in the morning.

I am pretty sure it is the sensor going bad.  From what I have been seeing this summer, a lot have gone bad.  What seems to be happening is that water has got inside the chamber and flooded and shorted the unit.

Be sure that when you call them, you let them know if you have a FARS or passive (no FARS)   the sensor itself is the same, but the passive comes on a plate that fixes to the top of the chamber,  the FARS goes on the bottom .  Also have them send you the two spacers and screws.  On the FARS it mounts upside down on the two spacers and there is a very slight clearance from the botton of the chamber.  Personally , it would seem to me that if it were rain, one would want it to clear about an inch... however.. I don't design them.

[LFWX]

Well, I didn't find anything unusual while cleaning the station today. Tried some compressed air anyway. Now that the sun has set, the humidity has started dropping when it should be rising, guess I'll be calling Davis in the morning.

I am pretty sure it is the sensor going bad.  From what I have been seeing this summer, a lot have gone bad.  What seems to be happening is that water has got inside the chamber and flooded and shorted the unit.

Be sure that when you call them, you let them know if you have a FARS or passive (no FARS)   the sensor itself is the same, but the passive comes on a plate that fixes to the top of the chamber,  the FARS goes on the bottom .  Also have them send you the two spacers and screws.  On the FARS it mounts upside down on the two spacers and there is a very slight clearance from the botton of the chamber.  Personally , it would seem to me that if it were rain, one would want it to clear about an inch... however.. I don't design them.

Davis is sending a replacement sensor for $72.00, tech support said the spacers are included with the sensor. If not, I have some spacers & screws I purchased at Lowes many months ago, and then misplaced (naturally I'll find them in "the last place I look").

[Aardvark]

Well, I didn't find anything unusual while cleaning the station today. Tried some compressed air anyway. Now that the sun has set, the humidity has started dropping when it should be rising, guess I'll be calling Davis in the morning.

that is good.  The spacers say 1 inch, but they are not.. and I didn't have the right size, but I hope it will arrive quickly.     What I had was both the temp and humidity dash out for several hours, then as the unit heated up during the day  it came back.  So I looked at the data  and saw this happen several times  and I called Davis and the saga began.

Same thing with my soil moisture station, one channel, the temperature would decrease as the moisture increased  and I could superimpose graphs of both readings on each other and it would match. With that I was able to  play musical sensor and various combinations.  I figured it was the board, replaced the unit and so far things are fine.    I looked at the old one today and there isn't anything I can see wrong with it visually.

[moehoward4]

Yup, mine just died, all dashes for temp, hum, and dewpoint. 2nd time this has happened in a heavy, driving rain in the past 3 weeks. I called Davis and they are sending a new T/H sensor for $ 72 and I'll have to send back the bad one. I can't complain, this one lasted a little over 5 years. It was the original sensor.     Jack

[LFWX]

A new sensor did solve the problem.
It came with the new style of insulating disk (not used with the FARS), but not the spacers & screws for inverting the sensor when using the FARS setup. I'll have to request them again.

Back to normal
http://weather.gladstonefamily.net/qchart/D1039?date=20110823&addnl=KHAO&addnl=D6341&addnl=D1886&addnl=AN848&addnl=D3149&addnl=D2882&addnl=AN816&addnl=KMWO&addnl=AS636&addnl=C0176&Add+to+charts=Add+to+charts&.cgifields=addnl

[moehoward4]

Yeah, I resolved mine, too. I canceled the Davis order...it was going to take 10 days to get to me. Brian @ Davis said they ONLY ship on Wednesdays, and I wasn't waiting that long to get back in business. I ordered from Archer Trading Post the same day I ordered from Davis, and got it in 2 days. PROBLEM SOLVED.    Jack