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WH-3080-SOLAR new take on radio dropout

Discussion specific to Fine Offset and similar rebadged weather stations
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g0gcd
Posts: 8
Joined: Fri 20 Jul 2012 6:57 pm
Weather Station: Fine Offset WH3080 (Solar)
Operating System: Windows 7
Location: Rothwell NN14 6JE UK
Contact:

WH-3080-SOLAR new take on radio dropout

Post by g0gcd » Thu 15 Nov 2018 12:54 pm

I thought I'd share my finding.
Like so many others, I have had serious problems with wireless comms. I moved from a 433 system to 868 because of the interference from next door's wireless security system, so I was dismayed to find the initially good 868 system gradually deteriorating. I have even brought out the down button wiring so that my PC could detect loss of signal and automatically force a re-acquisition. When I was losing signal for over 12 hours each day, I thought I should do some proper investigation.
Firstly, my sender is about 3m up the mast. I've extended the wiring for the sensors, so that I could put the transmitter as close as possible to the receiver. I use two, one in the kitchen, about 1.5m from the sensor and one in the garage, next to the PC, another couple of metres away but through a couple of brick walls.
Being a radio ham, I checked the signal. I found that 'my' transmitter is centred on 868.320MHz but was audible for a good way each side of that frequency. The signal was very strong in the garage when it was working. I was getting solar information but not the other sensors. The most likely time for loss of signal was during the early morning but not always.
So I fetched it into the shack and froze it. It worked until the point at which the frost from the freezer spray melted and then started again a few minutes later. Due the delay from the real time clock, the FO panel didn't resynch for several/many hours later. Thinking that the problem wasn't temperature but moisture, I then sprayed it with a fine mist of water. Bingo - it stopped and restarted later.
So something was being upset by moisture. Next I monitored the CPU clock by putting an oscilloscope on the crystal. The oscillations were strong until the point of frost melt and then they died out. Odd.
Fortunately, then, I tried to probe transistors around the CPU to see what was shutting the CPU down. One pad caused the CPU to shut down and restart, despite the meter being very high impedance. That is, it shouldn't have.
So digging around this transistor I find that it is linked to the lead from to the solar sensor and receives the 'reset' switch signal from to solar unit. Shorting this pad to negative shuts the CPU down - in fact triggering a restart. The thing is, there doesn't appear to be any pull up to positive.
What I think is happening is that the lacquer coating is aging and cracking off, allowing moisture (we know that as dew!) through to the board and the film of water conducts enough to trigger a CPU reset, or even a partial one. I had made it worse by connecting a long wire to it (the lead up to the solar sensor) which acts as an antenna and inserts any stray signals into this sensitive point.

I can't believe that this part of the circuit is intended just to float around aimlessly. Somewhere the pull up must have become detached. I have now soldered an 820k ohm resistor from the pad to the battery positive and for the first time in a year, it's run all through the night. In fact, I'm now 48hours+ with a reliable link.

Happy to supply photos if anyone finds this info useful.

Good luck, John

g0gcd
Posts: 8
Joined: Fri 20 Jul 2012 6:57 pm
Weather Station: Fine Offset WH3080 (Solar)
Operating System: Windows 7
Location: Rothwell NN14 6JE UK
Contact:

Re: WH-3080-SOLAR new take on radio dropout

Post by g0gcd » Thu 15 Nov 2018 12:57 pm

Just a thought. I'd even considered junking the whole lot, as several users have advised.
Any recommendation for a similar budget system with PC connectivity and solar measurement? There doesn't seem to be may around !

uncle_bob
Posts: 476
Joined: Wed 17 Aug 2011 2:58 pm
Weather Station: WeatherDuino Pro2
Operating System: 2008
Location: Canberra

Re: WH-3080-SOLAR new take on radio dropout

Post by uncle_bob » Mon 19 Nov 2018 11:24 am

Take a look at the link in my signature, I think might be right up your alley :)
Interested in building your own Weather Station? Maybe check out the WeatherDuino Pro Project Here
Conder, Canberra Weather
Image

g0gcd
Posts: 8
Joined: Fri 20 Jul 2012 6:57 pm
Weather Station: Fine Offset WH3080 (Solar)
Operating System: Windows 7
Location: Rothwell NN14 6JE UK
Contact:

Re: WH-3080-SOLAR new take on radio dropout

Post by g0gcd » Tue 20 Nov 2018 1:37 pm

Thanks Uncle_Bob. That is of interest. I'll probably go that way because nothing short of a Davis seems to meet all of my needs.

Anyway, the addition of the pull up has given me some breathing space. After one week, I haven't had a single drop out. After years of living with the problem, recently only 6 to 8 hours working each day, it's so weird to see the panel showing data EVERY time I look at it. And now I can start to work on the data that it's collecting, which was the original plan.

That's right, not one drop out in a week !

uncle_bob
Posts: 476
Joined: Wed 17 Aug 2011 2:58 pm
Weather Station: WeatherDuino Pro2
Operating System: 2008
Location: Canberra

Re: WH-3080-SOLAR new take on radio dropout

Post by uncle_bob » Tue 20 Nov 2018 8:54 pm

That's a great find (the pullup resistor). I think a photo of where you put it might help others immensely.
Last edited by uncle_bob on Wed 28 Nov 2018 12:57 am, edited 1 time in total.
Interested in building your own Weather Station? Maybe check out the WeatherDuino Pro Project Here
Conder, Canberra Weather
Image

g0gcd
Posts: 8
Joined: Fri 20 Jul 2012 6:57 pm
Weather Station: Fine Offset WH3080 (Solar)
Operating System: Windows 7
Location: Rothwell NN14 6JE UK
Contact:

Re: WH-3080-SOLAR new take on radio dropout

Post by g0gcd » Tue 27 Nov 2018 10:34 am

TWO weeks!

I'm looking forward to monitoring my first weather event in ages (Storm Diana, due tomorrow) - as the station has traditionally reported 'lost sensor contact' just as things get interesting.

I've attempted to identify the rogue pad below. The reset circuit seems to be comprised of C1, R10 and Q2. The new 820k resistor sits flush to the track side of the board, across the board just above the negative battery pad, carefully spaced so that the leads don't touch anything else. The two other wires you see soldered are there so that I could use a bench power supply to emulate the rechargeable alkaline batteries (at 2.71 volts, if anyone is interested, which I thought was low).

20181112_105944a.jpg

When it next comes down for servicing, I'll add a photo with the actual resistor in situ. I didn't photograph it before it went back up because I didn't believe that this was going to help in any way. The resistor needs to be as large (in value) as possible as it must increase battery drain and that needs to be minimised, of course. I used 820k because there was some degradation of the oscillations when I sprayed the board but they didn't cease altogether. Using a water spray is quite extreme - I think that the most that the sender has to deal with will be fog condensation - so there may be some scope in increasing the resistor value, balanced against the loss of protection against moisture.

As previously mentioned, I have a 433MHZ version (not solar) which was thrown (in disgust) to the back of the garage. I'm now going to see if the same 'fix' works on that. I'll photograph that with the resistor installed before the transmitter becomes inaccessible!

I am aware, of course, that an easier route may have been to simply soak all of the old protective lacquer off the board and then reseal it !

All the best,
John
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