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Thread: Ws2812b + 74hct245 random failure

  1. #1

    Ws2812b + 74hct245 random failure

    Hi guys. I am trying to diagnose a very strange issue and could use some help. I have 12 WS2812b LEDs hooked up to a 74hct245 chip being driven by a teensy lc. The LEDs have been working fine for about a month until today, they randomly stopped listening to my commands. I've flashed the basic WS2812Serial test program which I can confirm worked previously and heres what happens:

    1. Some of the LEDs turn on, but they don't seem to listen to the color I specify or the LED in the chain I specify.

    2. The LEDs seem to mostly just be turning white, although that's not the case 100% of the time.

    3. I've checked power to the 74HCT245 and it's getting a reliable 5v.

    4. The teensy seems to be working fine, it will consistently print out correct serial data and send correct commands via usb.

    What could be going on here? Why would this just all of a sudden stop working? These are not intermittent connections, the connections between components are traces etched into the board and seem to be reliable. Could poor grounding have fried the 74hct245?

  2. #2
    Looks like it was a combination of a dead LED and a cold solder...Chinese pcb manufacturing has had about 8% margin of error now...

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