I’m working on some overly complicated under cabinet lights, which I’ve posted about a few times in the past. My latest issue is that LEDs keep dying. Usual symptoms are that the bad LED will be orange while others are white. LEDs after the bad one will either not show anything, or display very erratically. I’ve found that sometimes pressing or twisting the bad LED will temporarily “fix” it, but not always. So far I’ve had to replace about 5, and my supply of spares is running out.
Here is an awful diagram of my set up: http://i.imgur.com/NiKkZub.png . The most recent LED to pop was towards the end of Strip 1. Others have been towards the beginning and middle of Strip 1, as well as towards the beginning of Strip 2 - but those were all using the old power supply. I’m using a Photon to drive them. The photon’s outputs are shifted from 3.3V to 5V with a SN74HCT125N. Data lines both have a 330 Ohm resistor on them.
So far I’ve tried 2 main things. My initial setup didn’t have capacitors across the power supply input, so I added those. Also I found that my power supply was outputting 5.5V (with no/low load, not sure about full load because I stopped using it) and the WS2182Bs supposedly only tolerate up to 5.3V. So I bought a new power supply that is supplying 5.32V under no load, 4.3V under full load (all LEDs full white).
One of my thoughts has been that heat is killing them. Strip 1 is directly over a stove, and is also where most have died. But it looks like the operating temperature can be at least 100C, maybe more depending on what data sheet you look at. And these are in silicone tubes which should be insulating them fairly well. Currently the strip over the stove doesnt have its ends sealed (since I keep having to open it up to fix it), but the LEDs at the ends have never been the ones to die. LEDs on strip 2 near the stove have died, but so far not since I’ve replaced the power supply (knock on wood). I may temporarily install strip 1 somewhere else for a while to rule that out.
My other thought is that the old power supply outputting 5.5V has weakened some of them. The small “Strip 1” is what I’ve used to for individual testing most often (half because it breaks most often, half because it’s easiest to remove). Now even though I’m using a better power supply, some are dying due to past events.
My final thought is that they might just be bad. Making them “work” by pushing on them makes me think that there are bad internal connections. They may be failing on this strip more often due to the added mechanical stress of installing/uninstalling them, although I dont think I’ve been very rough.
I dont know. Any other thoughts?
(sorry about the novel)