Yes. I've bought 1000 chinese new LEDs. 50 where dead from the beginning. About 500 where dimming low after a few seconds of supply. They still light but with low intensity. On 4/9/07, Rob Robson wrote: > Sounds like a case of Chinese dim sum. > > RR > > ----- Original Message ----- > From: "alan smith" > To: "Microcontroller discussion list - Public." > Sent: Monday, April 09, 2007 4:06 PM > Subject: [EE] LED's dying...dimming but not dead > > > > Have a board with several LEDs on it....ok....about 100. Getting some > > strange failures, in that some of them will dim out...but not die. Its > > the standard configuration of the current limit resistor hooked to +V, and > > a NPN switching ground. I had them short the collector to ground to see > > if that fixed it (ie...transistor not turning on hard enough) no effect. > > I think...need to verify, that there was no change in the voltage drop > > across the current limit resistor. They put a higher voltage across the > > LEDs and no change (that I saw on an earlier failure). These have been > > running for better part of a week now, and all of a sudden they do this. > > Granted its one or two out of 100....and they are chinese manufactured (I > > did say to them....the quality can be questioned...but usually its > > brightness between batches) and they have used them in the past without > > issues on a different product. > > > > Just wondering....what might make them....sorta fail dim like this? > > > > > > --------------------------------- > > Expecting? Get great news right away with email Auto-Check. > > Try the Yahoo! Mail Beta. > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist