Topic: VP2 ISS drops transmission at night

[petec2]

Dear Friends
I have read a good bit about this issue but I'm stumped. My ISS has stopped transmitting data packages to my Console and Envoy at night.
The separate anemometer packages (station 2) still arrive perfectly (that separate transmitter is further away).
I changed the battery in the ISS (using new duracell CR123) but the ISS still quits about 2h after dark and then comes on-line again with sunrise. I tried another new CR123 (exp date 03/29) and the same happened. Console showed 'Low battery warning station 1', then R and then 2h later no data packages received from ISS (L)
Can anyone give any tips on solving this? I'd be very grateful.
best wishes
pete coxon
ps the VP2, envoy, console and anemometer etc has been working perfectly in this configuration and on this site since 2011

[johnd]

Sounds like a classic supercap failure on the ISS transmitter board. See:

https://www.manula.com/manuals/pws/davis-kb/1/en/topic/supercap-faults

[ashland weather]

I had the same problem on an 8 year old system. I found out the problem was at the console showing low battery. another console did not show low battery. I removed all power to the console showing low battery and let it set for a while.  I restored the power and that fixed the problem.

[petec2]

Thanks johnd and apologies for not checking this. I'd read the excellent manula stuff but hadn't believed just how fast the CR123 was eaten. i just followed the instructions you highlighted and took off the cover and the + side of the supercap is 'gunky'

What's my best bet? Live in Ireland and want to get this fixed

 [ You are not allowed to view attachments ]

[johnd]

Thanks johnd and apologies for not checking this. I'd read the excellent manula stuff but hadn't believed just how fast the CR123 was eaten. i just followed the instructions you highlighted and took off the cover and the + side of the supercar is 'gunky'

What's my best bet? Live in Ireland and want to get this fixed

If you're handy with a soldering iron then you could try just replacing the supercap. But this tends to have only a roughly 50/50 chance of long-term success. Otherwise I'm afraid that it's a new SIM board required.

[Storm017]

Here is a document on replacing the ISS Supercap:

https://www.scaledinstruments.com/wp-content/uploads/2018/03/Pro2%20Supercap%20Replacment%20v1.pdf

[petec2]

thanks to johnd and storm017 and pointers to really good websites i managed to snip out old supercap leaving the upright leads, clean gunk off latter with a nail file and solder in a new supercap (as in step by step pdf posted by Storm017 but with shaky soldering...).
cap was £20 incl tax and postage, soldering iron €11. so fingers crossed it holds out... realise its 50:50 but for now it works
pete [ You are not allowed to view attachments ]

[azchrisf]

thanks to johnd and storm017 and pointers to really good websites i managed to snip out old supercap leaving the upright leads, clean gunk off latter with a nail file and solder in a new supercap (as in step by step pdf posted by Storm017 but with shaky soldering...).
cap was £20 incl tax and postage, soldering iron €11. so fingers crossed it holds out... realise its 50:50 but for now it works
pete [ You are not allowed to view attachments ]

This is exactly what you should not do...Clipping the leads is not a proper repair. This will fail in short order.
Whoever posted that guide should be shot. Anyone who has done any kind of soldering and board work who is not an amateur knows you don't do that. Does it work? Yeah. Just like twisting wires together does for a short period of time...get the point?

[petec2]

? for 'clip' read snip and then solder?

[davidmc36]

It’s not really that hard to clip the leads at the cap, hold one at a time and heat with gun to remove.

Clean off all the old solder and corrosion with desolder braid, like $1.25 on Amazon, and put a clean part in.

The old gunk there is waiting to spread.

[dalecoy]

Although I prefer to do this sort of replacement in the recommended way, by removing the old component and soldering the new one into the pads on the board.........

I have an engineering degree, and many years of experience.  And in this case, I don't see anything "wrong" with the pictured replacement.  The leads and the component look clean, and the blob-solder joint looks just fine.  If it works electrically, then the replacement should have a full, functional lifetime. 

For someone with little soldering experience/expertise, I believe that's an excellent approach - and probably a bit preferable to the danger of shaky hands trying to remove the old wires, without damaging the board and requiring a complete replacement.

[92merc]

One of the theories as to why these caps fail, is due to bending of the leads.  The snip and solder method is trying to avoid putting stress on the leads by not bending the new leads.

I've done enough soldering.  As long as you don't have a big blob, or sharp points at that joint, it'll be just fine.

[Aardvark]

While I don't have "engineering degree," I do have many years of experience with the Davis line.   For me when my ISS was doing exactly what yours did, I actually fiddled with the board and was able to remove the old cap from the board by heating with a low volt iron , the solder.  then bend the leads and insert them into the former holes and re soldered, trimmed. I even put a little cushion between the super cap and the board as Davis suggested.

I found it odd that so many of these tend to fail, originally I thought Davis bought a bad lot, then I realized they were cheap.  Anyway,  lacking the engineering expertise, I used common sense, and fixed it.

[petec2]

yes. i used soft double sided (very)adhesive pads (for outdoor use) to stick the cap down prior to soldering
i guess only time will tell but its working and survived Storm Barra last week. if my repair goes pear-shaped i'll try again and then buy a new iss board...
thanks for all the feedback

[dalecoy]

..... I actually fiddled with the board and was able to remove the old cap from the board by heating with a low volt iron , the solder.  then bend the leads and insert them into the former holes and re soldered, trimmed.

...  Anyway,  .... I used common sense, and fixed it.

And that is, of course, the best way to do it, if you are confident.  Other less-neat ways will work OK, as petec2's experience seems to indicate.