Strange behaviour - pixels stuck on, starting mid-string

cdnbob

New elf
Joined
Jul 26, 2014
Messages
33
Location
Ottawa
I'm experiencing a confounding problem. I have 4 pixel strings in sequence along my roof line, and starting at the mid point of the third string and through the entire fourth string they all stopped following the sequence being played and went to full on white and stayed there. I rebooted the FPP, and then the P12S, but they were still stuck on. I then powered down everything, and they went off, and now they're not lighting up at all.

I'm worried it's a bad pixel that wasn't water proof. We're having a freezing rain event here, and the first pixel of the all-on group wasn't all white - it had a reddish tint to it. I've hung the strings under the edge of the roof line to shelter them from direct rain, snow and ice exposure, but drips from the roof above can still run down onto them. The start of the problem is at the highest point of the strings and the most exposed point.

Would a water damaged pixel explain the observed behaviour?

Some more details:
- The strings are 5v WS2811 technicolor pixels from Ray Wu - four strings of 50.
- Controller is a P12S/P12D. I use 2 outputs for the 4 pixel strings, 2 and 2.
- I run 24v cable along the entire run with step-down to 5v at the start of each string and at the end of the fourth. All the connections are tucked back well under cover and not exposed to any wet. The DC-to-DC converters are sealed IP68 units.
- There is no break in the wiring at the mid point of the third string where the problem began.
 

AussieDoug

Full time elf
Joined
Dec 1, 2012
Messages
375
I would look at changing out your last working pixel & the first one that isn't.
Was it working at any stage before this issue?
 

fasteddy

I have C.L.A.P
Global moderator
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Apr 26, 2010
Messages
6,645
Location
Albion Park NSW
Sounds like a dodgy pixel to me and the fact that they are the technicolour makes me think its the pixel and you may be getting water in them as many have already experienced.
The technicolour pixels have already been noted by many users as failing with rain. In most cases it can be dried out and be OK, but not always

Refer to this thread on issues with the technicolour pixels http://auschristmaslighting.com/forums/index.php?topic=6777.0

Sounds like you are doing enough power injection if at every string
 

cdnbob

New elf
Joined
Jul 26, 2014
Messages
33
Location
Ottawa
Yes they were all working nicely prior to the rain starting. I was really liking the way they looked.

I have them all hanging pointed downwards. I thought that would further reduce the chance of water infiltration. Apparently not enough.

So I'll need to swap a pixel out. I have spares available, but this will be done up on a ladder, and soldering wires up there is not an option. Can I reasonably anticipate to get by with twisting wire ends together and sealing with heat shrink?
 

cdnbob

New elf
Joined
Jul 26, 2014
Messages
33
Location
Ottawa
I followed AussieDoug's suggestion and swapped out the two pixels that were the last of the working and the first of the non-working pixels and the lights are on once more.

Thanks Doug.

Even though we've had some dry days since the rain, the lights didn't come back on, so I replaced the two. And now I'll see how I get through the next round of wet weather - forecast is for mid week.
 
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