Need an expert opinion:

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(T Scholz) #1

Need an expert opinion:

I have a SK9822 LED-strip (288 LEDs) controlled by FastLED running on an Espressiv ESP32 Dev Kit. The strip is powered from an external PSU with 20 A, connected with common ground to the ESP32. On the data pin I included an 410 Ohm resistor. Everything works fine, except:

There are 7 LEDs at the end of the strip, which do not respond properly. I am unable to control them with normal sketch-code. Nevertheless some of them start to lite up in full white randomly and don’t turn off until I power off the whole system.

Are they simply defect, or is there something I could do about it to fix it?

Thanks for any help!

(Jeremy Spencer) #2

You’ve almost certainly got a dodgy led or a poor solder joint in the strip.

Try pressing on the first dodgy one or the last good one.

If pressing helps, it is possible to carefully flow a little solder onto the pads of the loose chip. I’ve done this successfully.

If it’s a dodgy led, you’ll need to cut it out and solder the strip back together. It’s generally best to take out the last good one and the first dodgy one or you often end up doing the job twice.

(T Scholz) #3

I think burning is the problem. I’ve attached a foto and although the first 10 LEDs look badly burned, surprisingly starting from LED No. 8 (9, 10…) all seem to work properly. And although the first 7 look burned, once in a while they turn on full white, meaning the LEDs itself do work, maybe the chip is not anymore full operating.

So probably I have to shorten the strip up to LED No. 10 or 11, right?
missing/deleted image from Google+

(Jeremy Spencer) #4

Yes, those LEDs definitely dodgy! What happened to them??

Try just cutting off the 7 that are worst affected

(Mark Estes) #5

you can always solder a bit of strip back on if 288 is an important number. I have a short piece of what looks like a similar strip in my junk pile. PM me your address and I will mail it to you.

(T Scholz) #6

@Mark_Estes Hi Mark,
thank you very much for this very kind offer! But in fact the number of LEDs doesn’t matter that much, therefore I cut it already and soldered the cable to it.
Was a stupid wiring mistake and with the 20A PSU the stripe sent me faster smoke signs as I was able to find the switch…

(Mark Estes) #7

@T_Scholz fast smoke signs: been there…