I think there are quality problems are with the strings... even the newest sets that came plastidip'd. Many strings might be borderline working, and if the string runs for a while it might even appear good when it has problems. Maybe its heat-related, maybe rosin residue, ...I'm just seeing high failure rates at a string level, and I'm seeing strings pass testing only to go bad later.
I use 3-core connectors to allow separation between each string and SSC, and in my preparation I go through each string with the same SSC using test firmware.
When I started off with 128-pixel strings, and then weeded out 20% of those strings with immediate problems -- rainbows or a rogue pixel. Then I had 12 128-pixel strings running test mode firmware for 6 hours. 10 of those 12 strings turned into rainbows or showed up with rogue pixels. The rogues usually have one color that won't work -- usually red. Sometimes rogues cause themselves problems, but often a rogue will cause all pixels that come after to have their colors shifted as if they are one color behind in the sequence.
I then started trimming the strings to 85 pixels, and I had great success overnight. No problems.
Later, I had 40 tested strings that became tangled and my helper tried to separate them... I guess more roughly than they should have been handled. I had 9 out of my 40 85-pixel strings no longer working. I found that 2 of the 9 became rainbows, and the other 7 of the 9 had one or more rogues.
In hindsight, I think my initial testing thatpassed too many strings that turned out to have rogues. I found that I had several strings show a rogue with a missing color, that might affect pixels later in the string. As the string ran the test mode for several minutes the rogue would clear up and the string would look good. But as I started connecting and disconnecting the string I could get that pixel to go rogue again and again. (Obviously this is not good... when I sequence RGBs I don't want to warm up each pixel so that it come on when I want in the color that I want.)
I don't think it is the SSC, I used the same SSC and had 50-70% of the strings without a problem. I've used different SSCs and seen similar behavior.
I suspect that we'll come to the conclusion that the pixels are very fragile and even when you have a good string it is easy for the string to become broken. As the strings warm up I see them working a little better -- but let them run for a long time and you'll start seeing rainbows.
