Author Topic: Water Intrusion from an Obscure source  (Read 1320 times)

Online JonB256

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Water Intrusion from an Obscure source
« on: December 24, 2014, 11:09:10 AM »
It rained a lot on Tuesday morning but did quit around 1pm. No problem. Show should run just fine.

But, no.  DMX Universe #1 was not acting right. It is almost all my non-Pixel front yard items. Mega-tree, Reindeer, mini-trees. Important stuff, and they are just going crazy. Even when I pulled the CAT5 cable to the first controller in the chain, some items were still flickering.

Of course, the show had started at 5pm and I notice around 5:30pm. Not quite dark yet. I am crawling around on my hands and knees, board by board, but by process of elimination, I do finally isolate the problem to a 12vdc 16 channel controller for my Mega-tree star (rope light). With it out of the circuit, every thing is normal. Show continues all night without problem and without the Star. :(

I could see nothing wrong (in the dark) or by Smartphone flashlight. I put off troubleshooting until today. During the night, though, it occurs to me that there could be a water path directly onto the circuit board. By daylight, I check and sure enough, there is a big, bubbly looking mess of water all over the PIC and RS485 chip and their sockets. Using distilled water and a fresh toothbrush, it cleaned right up. After a hair dryer treatment, it was tested and checked out. No damage.

Now - the source of the water (in case you skipped to the end, anyway) -

From the top of the 18' Mega-tree, I used 4-wire speaker cable. Nice heavy gauge stuff (not oxygen free copper, though). But where I soldered and heat shrunk it to the Rope Light at the top, I did not seal the white, outer protective cover. Water collected in that little opening and went all the way down, like it was a pipe, and onto my board. The white cover ended right over the center of the board. The gooey stuff must have been from the wire insulation that washed down with it.

Since I can't get to the top to seal the wire, I cut the outer cover and peeled it back outside the CG-1000 case. There was a lot of water inside, confirming my problem.

Tonight, we'll see what new problems may appear. :)

Online CaptainMurdoch

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Re: Water Intrusion from an Obscure source
« Reply #1 on: December 24, 2014, 11:28:17 AM »
Interesting, good troubleshooting.

It shows that even a little drip loop at the bottom of the cable before entering the case won't prevent water intrusion from happening when the water is 'forced' through the drip loop by the 6-8 feet of water in the line up to the tree topper.
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Chris

Offline mkozik1

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Re: Water Intrusion from an Obscure source
« Reply #2 on: December 24, 2014, 12:13:59 PM »
I have always been told 'water will find a way' but this is crazy!!
- Mark

Online JonB256

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Re: Water Intrusion from an Obscure source
« Reply #3 on: December 24, 2014, 01:06:27 PM »
Between capillary flow and 18 ft of head pressure, it did find a way. An AC controller would have destroyed itself.

Offline drlucas

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Re: Water Intrusion from an Obscure source
« Reply #4 on: December 24, 2014, 04:47:06 PM »
I was lazy this last weekend adding another controller to my show and after the rain yesterday I woke up to a white light. Based on past experiences this is the light of death of a usc. Sadly I know better. Tomorrow wind pending I'll be on the roof replacing it. At least it'd not overly critical for the show - but water is evil
Ryan

Offline burcjo

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Re: Water Intrusion from an Obscure source
« Reply #5 on: January 03, 2015, 09:42:03 AM »
I have discovered the 'drip loop' concept is always applicable. It's saved me a ton of heartache and equipment.

Everything and anything going to a controller or light string has a loop that let's water follow gravity to run off/drip off before making its way to something expensive.

Hope this helps!

Online JonB256

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Re: Water Intrusion from an Obscure source
« Reply #6 on: January 03, 2015, 10:37:49 AM »
In my case, a drip loop was ineffective. (Since I had one) My cable was actually a long tube with the opening inside my case.

Offline Steve Gase

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Re: Water Intrusion from an Obscure source
« Reply #7 on: January 03, 2015, 07:00:04 PM »
i had my own version of this problem...  I made my own meteor tubes that enclosed a pair of 1M rigid strips and a buck converter and a uSC. 
the tube was suspended by a length of paracord that came through the top -- a PVC endcap glued to a fluorescent tube light guard.

anyway, we had torrential rain last night and the paracord was soaked when I took the tubes down today.  the paracord was a highway for all of that rain to travel through the tube.

i didn't have any power connected at the time, but I now need to rethink my design...  i had been using the cord to draw the strips into the top of the tube, so the hole in the endcap was a problem waiting to happen.
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Online CaptainMurdoch

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Re: Water Intrusion from an Obscure source
« Reply #8 on: January 03, 2015, 08:47:59 PM »
i had my own version of this problem...  I made my own meteor tubes that enclosed a pair of 1M rigid strips and a buck converter and a uSC. 
the tube was suspended by a length of paracord that came through the top -- a PVC endcap glued to a fluorescent tube light guard.

Maybe put a bent S-hook in the top of the tube sealed with hot glue or epoxy and hang that from the paracord.  I am considering making a few similar to what you describe this year if I get the time.

 

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