Weather Station Hardware => AcuRite Weather Stations => Topic started by: ksgre02 on January 12, 2018, 04:20:47 PM

Title: 5 in 1; bad circuit traces or bad SHT21?
Post by: ksgre02 on January 12, 2018, 04:20:47 PM
as has happened to alot of folks, my 5N1 (circa 2012, with the older white SHT 21 module) has been reporting -40 when i last used it in 2015...we moved in 2015 and the 5N1 stayed in storage until a couple of weeks ago (due to spring cleaning of the storage unit)...I wanted to get active again with Wu and CWOP and didn't quite remember what problems i had back in 2015...so I got it up and running and, yep...-40 still, and the humidity is off as well...i did have a (RH/T) tower sensor that I set up as well...i also have the old acu-link bridge (now smart hub)...much to my delight, the acu-link hooked up to the new MBW with no hitches...the last time i used it was with the old Acurite web service...the tower sensor seems to be pretty close to NWS reports and local PWS in my vicinity...however, for the life of me I couldn't get Kevin Keys bridge reader to work...I was able to get to work for a few hours and then when i restarted my computer i couldn't get it to work...so i decided to go the meteobridge route....well as you know, I can't use 5N1 and tower sensors together to report to WU or CWOP...its either one or the other...with Kevin's app i could filter out the bad 5N1 temp and humidity reading before it was transmitted to the WU and CWOP services and use the tower...meteobridge doesn't have the configuration setting to do this...so I am reporting -40 because I don't want to lose my ability to report rain or wind speed/direction if I use the tower only...

My question after reading about so many that have had temp/humidity sensors "go out", is it because of bad and corroding traces on the temp/humidity module?...or a bad SHT21 IC??...has anyone, or is there a way to trouble shoot the actual chip itself???...or do people just chalk it up to a loss and replace without giving it a second thought??...i would figure to say that alot of supposed bad SHT21 chips were thrown out with the module, but only because the circuit traces were bad (corroded/shorted) and NOT the sensor chip itself...if you think about it, the sensor temp/humidity module is not protected well from the environment (in a wind tunnel with dust, bugs, i am sure on a very foggy night dew collects on the board itself exposing the components to direct moisture)...and where i live (75% average annual humidity), if the sensor PCB was manufactured with poor coating (which it seems to be) then i can understand the traces being pitted and corroded like mine were...the chip itself is pretty well fortified in copper lead frame and epoxy housing...i would assume that the only reason the chip (hardware) itself would fail would be from a physically damaging event (lightening strike, being run over by a car, lawnmower), but would a surge in DC voltage (from the battery source) be enough to burn it up or damage it physically?!!?...just thinking out loud, i am not an electrical engineer so I don't know...

I tested continuity on my temp/humidity module and found at least one trace that is NOT showing continuity...I put the 5N1 back together because I was considering buying the new replaceable temp/humidity module and soldering it on the the board (my 5N1 isn't compatible with the plug and play temp/humidity version)...now, thinking about it...i think i am going to try and bridge the bad trace on the current temp/humidity module and see if that doesn't fix the problem...attached is the spec sheet for the SHT21 and it has alot of good information, even if you aren't an electrical engineer...gives you the interface definitions/info of the different interface codes of the SHT21(VDD, VSS, SCL, SDA) and other interesting info on sensor communication etc

I will let yall know if my "trace bridging" solution worked or not...

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Title: Re: 5 in 1; bad circuit traces or bad SHT21?
Post by: DoctorKnow on January 12, 2018, 07:04:18 PM
You can use the separate tower sensor with meteobridge. Just block the main 5n1 sensor temp and humidity reading and select "outdoor" for the other thermometer/hygrometer tower sensor. You must turn both temp and humid green independently.
Title: Re: 5 in 1; bad circuit traces or bad SHT21?
Post by: nincehelser on January 12, 2018, 07:16:03 PM
It is possible for the SHT21 sensor to become contaminated due to "stuff" (chemical vapors, pollutants, etc.) getting in the small window on the chip.

People have replaced the STH21 itself in the past, but you need some decent soldering skills.  As you're aware, there's also the possibility of bad traces on the circuit board itself.  The circuit board has become more and more simplified over the years.  It sounds like you have one of the older "double decker" setups.

In any case, Acurite sells the compete module for $10.  Acurite says it is only for the new 5n1 sensors with pluggable modules.  However, if you cut off the plug and solder it to the main board, it will work just fine.
Title: Re: 5 in 1; bad circuit traces or bad SHT21?
Post by: ksgre02 on January 13, 2018, 05:33:40 PM
Thanks DrKnow...I didn't thoroughly read the meteobridge wiki  :shock: :shock: :shock:... the balloon on the historical data table doesn't pop up in google chrome...a left click does, however, give me the option to block the bad sensor readings...phew, thanks!!!...I would still like to know if my 5N1 temp/humidity sensor would be repaired if I did the trace repair...but since I now have my 5N1 and tower functioning like i want it to now...I don't know if I want to spend the time/stress trying it...
Title: Re: 5 in 1; bad circuit traces or bad SHT21?
Post by: ksgre02 on January 22, 2018, 01:31:03 PM
Well, after seeing alot of tutorials on fixing bad PCB traces, I cleaned up the SHT21 PCB and scraped off the one suspect trace, sure enough the trace was corroded thru...my temporary solution, because there is no longer a radio shack and I don't have supply of flux, small wire or PCB varnish/coating to do some trace bridging (as per the tutorial)...I used a small shielded wire (for auto electrical) and soldered the wire between the two ends of the suspect trace...got continuity...and fired the 5N1 up...VIOLA!!!...my temp started reading immediately on the acurite console...humidity was suspect, but as soon as sited the 5N1 back where it was...the temp and humidity started falling in line with NWS readings for the area...i don't expect for the mods to hold forever, the humidity down here wreaks havoc with any metal...but glad to know that the SHT21 wasn't bad as far as temp goes...I will keep and eye on the humidity reading as it is starting to fluctuate...
Title: Re: 5 in 1; bad circuit traces or bad SHT21?
Post by: daman on January 22, 2018, 02:48:02 PM
thanks for the update