Well this is annoying. This LED was a good quality one with well balanced chips. But despite running the 50W LED at just 20W it seems to have developed a stress failure affecting the gold-wire bonds from the chips onto one side of the DC busbar.
I'd guess that the bonding machine may be set to a single bonding current, so it's a delicate balance between not damaging the chips and getting a decent attachment onto the heavier busbar.
This LED would work when first turned on, but gradually the strips would start flashing on and off with some going out completely, until one was left and the light cycled on and off randomly as the LED heated and cooled.
I'd guess that the bonding machine may be set to a single bonding current, so it's a delicate balance between not damaging the chips and getting a decent attachment onto the heavier busbar.
This LED would work when first turned on, but gradually the strips would start flashing on and off with some going out completely, until one was left and the light cycled on and off randomly as the LED heated and cooled.
I guess I got lucky. I have 2 – 100 w cobs with separate drivers, fan cooled heatsinks on LED's. Have been running for 4 years.
so much for long life power leds
hi clive, another youtuber suggested i visit your page and watch your video on under driving COBs., the only problem is i cant seem to find it ? lol, does this ring any bells for you ? maybe you have covered the topic but listed the video by another discription ? any help would be greatly appreciated mate 😉 cheers
THERMAL EXPANSION I HATE YOU!!
get the chips that have 2 bond wires going to each led!!
Ive got one of those and it's been hella reliable!!!
mine has 2 gold bond wires going to each LED chip and connecting to the bus bars
Works great
mine was only 10$ from amazon and came in 2 days! great deal. and the heatsink its got is made of actual copper and its really good at dissipating heat
I remember when LEDs were first shown on Tomorrow's World in the UK. They were going to be even better than sliced bread. They would never need replacing, would produce virtually no heat, filament lamps would disappear within a couple of years, and we'd have whole walls made from an LED! OK they were only red.
So essentially, all the cobs from eBay could eventually suffer from this problem. The risk of this problem probably goes up right alongside wattage. How long did you run the chip before it failed?
where are the best suppliers for LED chips?
The best COBs use gold wire, I believe, but cheaper metals are used and failures like this increase.
lmao!
I never had much luck with the cool white versions of these. For some reason either they fail or they have poor performance to start with. Never had one failing like that tough.
The warm white versions, have been good so far, have some on use for over two years. They are mostly 100W driven with 10, 20 or 50W drivers.
Ah so it's maybe time to make a spot welder, with of course blue led's (just to show it's on). Funny thing is, I always assumed it was the LED's themselves that was the fault.
its just clown science maybe? jk : )
The fuck? No dislikes? This is the only youtube channel where i encounter this regularly
this is why you use discrete leds from certain name brand manufacturers. the lamps I built around 'em in '09 are still going strong despite heavy use and questionable cooling : )
Looks like ther still is a way to go to get reliable high power LED array's!
Can you scrape away at it to remove the covering layers and attempt a repair?