Did you re melt the joints as a test first? If not then the problem could still have been a dry joint issue... though it would be odd if it affected all in one run of LEDs and not randomly across the board.
White LEDs fade with time, the datasheet for the particular device should be consulted.White LEDs change colour balance too - the basic issue is that the fluorescent yellowgel in front of the LED changes with time. The LED is typically blue/indigo/UV and theother colours are generated by fluorescence. Its hard to engineer a fully stable fluorescentdye - note that ambient daylight could be aging the dye more than the blue from the LEDitself even - only the manufacturer will have data on these processes as they are a propertyof the dye.The actual LED emitter itself can age too, but this is likely to be a smaller effect due tocrystalline semiconductors being more robust than organic dyestuffs.
@Chagrin: The shift registers/transistor arrays wouldn't have anything to do with it, considering the effected LED's are not connected through them, but are connected directly to the power and ground.
And a resistor I hope.It needs to be a higher value resistor than that connected through the transistor because there is more voltage across those than the transistor ones.
I would be interested to see how it is in another month.
Regarding reply#14:Right at the power input of the led strip, what value of capacitor did you connect?I would recommend anything from 220µF to 470µF.Right at the led strip and connected in series with the data line, what value of resistor are you using?I would recommend 220Ω, 270Ω or 330Ω.
Any more ideas now that the effect seems to be spreading?
I painted the back of this black, and at first it didn't wind up sticking too well or looking too good. It wound up working out though.
And so begins the arduous process of gluing in all the LEDs. I ordered 150 of diffuse white LED lights on ebay for next to nothing.
It will spread if something is wrong. Can you make sure you have a 220 R resistor and that the voltage is 5V.You need to subtract the forward voltage of the LED. Being white it might be as much as 3V so with that resistor you would get (5-3)/220 = 9mA. That should be well withing the limits of an LED, unless they are faulty or as I said the resistor or voltage is wrong, measure both with your meter.
Ahh, I originally stopped at the picture that mentioned "The RGB LEDs are a WS2812B strip".Note: Just to mention - some types of paint could be conductive or semi-conductive (however I don't think this is the issue).Careful there are no shorts (it appears some resistors could be shorting out).MAIN PROBLEM:It truly appears that the resistance code is red/red/black with black (multiplier) and brown (tolerance). If so, then these are 22Ω resistors and the excessive current will cause the LEDs to fail.The first 3 colors should be red/red/brown for 220Ω. EDIT: (I see Grumpy_Mike is a bit quicker than I)
I only have 1/4W resistors, so I am not sure if that would be too much load on the resistor.
No that will be fine.A thought struck me, could it be that the LEDs are getting hot inside those unventilated compartments?
Have you replaced any of the dim LEDs?Have you extracted any of the dim LEDs then tested them?