Cumulus Support

Am afraid this isn't Cumulus specific, but more to do with the weather station connection.....just wanted to tap into other owners knowledge.

I have on loan to clean and tidy up an Vantage Pro 2 console and external wireless instruments.
The item in question was thought to not being used, so was given to me to look at as it was known I had my own weather station.

The battery inside the ISS was dead, showing less than 1v.

So I bought a Duracell Ultra battery to replace it.
I can't get a connection from the transmitter.

I have read documentation, and see there should be a LED in the ISS flash whenever a transmission is made, but I have not seen this happen yet.

Can anyone give me any advice please?
I have checked all the connections, and they seem ok.
Is the battery up to the job, or should it be a lithium one....not sure the Duracell one is.

Davis do specify a Lithium battery for the ISS, and I've never heard of anyone using anything but a Lithium battery.

The LED in the ISS only flashes if you put the ISS into test mode, by turning DIP switch No.4 on (on is 'up'). So that's probably the first thing you should try.

Note that the battery is only for backup; in daylight the ISS is powered by the solar panel, which also charges up the 'supercapacitor'. When the solar panel stops supplying power, the supercapacitor takes over, and when the supercapacitor runs out of charge, the battery takes over. Faulty supercapacitors are (or have been) a known issue, and you need to check that. A visual inspection normally shows whether it's OK - it leaks when faulty.

steve wrote:Davis do specify a Lithium battery for the ISS, and I've never heard of anyone using anything but a Lithium battery.

Upon closer inspection the battery does state it is Lithium, and is currently showing about 2.91v

steve wrote:The LED in the ISS only flashes if you put the ISS into test mode, by turning DIP switch No.4 on (on is 'up'). So that's probably the first thing you should try.

Hmmm, I couldn't get this to flash by putting the 4th dip switch up.

Interestingly I can here a tick tick noise from the ISS unit, similar to the sound made when the wind speed thing goes round.

Here's a pic of the internals.....has the design changed much over the years?...the firmware seems to date back to 2004.

The design hasn't changed much. If you take the four screws out that hold that white cover on, you'll see the supercap, a larger cylindrical thing approximately in the centre of the board. See if there's any sign of leakage. Your ISS is from a VP2 Plus (hence the UV and solar sensors) and was manufactured on 1st Dec 2004. I think that might just take it into the period where they started using the supercaps that turned out to be faulty.

Looks like we have leakage




Well that's a project for the Electronics department at the college who own the weather station I guess

Looking carefully round the board, I can't see an LED at all

It's just under the Comm socket, marked D21.

That would have been one of the first batch of VP2 stations manufactured.

The LED position will probably be just below the battery (position has varied on different board revisions) - it's actually not easy to see unless it's flashing.

A replacement supercap might resurrect it, at least temporarily. (We sell them, if you get stuck.) But sooner or later you'll need to consider getting either a new SIM board or a new ISS. The problem with the existing SIM is that it will only be compatible with the analogue temp/hum sensor, which is virtually unobtainable now - and the existing one won't last forever. So the upgrade path is then a new SIM board plus a new (digital) T/H sensor and the total cost starts heading up towards that of a new ISS, which is obviously a complete, brand new sensor assembly, including a new anemometer.

Sorry, probably more information than you wanted, but just by way of background.

Thanks for the info and help guys.

I guess I'll have to leave it with the electronics department to find out what they want to do about it.

I shall pass on your comments and explain the situation.

Will let you know if we get it back up and running again

Just a quick question.

Should the unit still not transmit from the battery power?.....or would the leaking SC prevent this?

Unfortunately not, the battery / solar panel charges the super capacitor and this then feeds the electronics so with this component failed it's a dead soldier.

Also you mentioned you'd been given this to clean up, and I see that it has a solar and UV sensor as part of the kit. Take care to use the correct method for cleaning these as they can easily be damaged, I believe that the manual will advise a very specific type of alcohol.

I've got a spare ISS board sitting here from which I've removed the faulty supercap, but not yet fitted a new one, and with a battery in and no solar panel connected, the LED flashes.

Part of the problem here is that there seem to be a variety of different symptoms and failure modes when a SIM board starts to go faulty. These may reflect different versions of the SIM board over the years or simply the fact that a given board can fail in more than one way.

For instance, the LED flashing is a good sign of a working transmitter, but it's not infallible. I've come across a number of boards with a flashing LED but from which no viable transmission can be received.

And a leaking supercap is obviously a sign of a component on the way out. Often the LED will still flash (or may start flashing if one of the supercap leads is cut - presumably removing a low resistance path across the supercap), but other times the LED can't be persuaded to flash at all - whether the failing supercap has caused consequential damage to other components in these cases is difficult to know, but obviously there's some rational explanation for this variable behaviour.

And replacing the supercap can often (maybe 70-80% of the time) fix the fault. But in other instances it won't or is only a short-term fix, with the board failing again before too long, again probably an indication of multiple failure modes.

None of this is very helpful I know, but it's just to point out that unfortunately there just doesn't seem to be a fully consistent set of SIM symptoms that will always reliably indicate whether a SIM is reparable or not. A flashing LED is always a good start. And if cost is an issue then a leaking supercap is worth replacing (if you can do it carefully). But sadly there just aren't any guarantees that a new supercap will necessarily be more than a short-term fix.