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Topic: WS2812B LED strip. Easy to damage? (Read 1 time) previous topic - next topic

MartynC

Hi,

I have 2m of WS2812B 144 per metre LED strips. I cut these in to segments of 20 LEDs with the intention of making a 20 x 10 matrix.

On the strip all the LEDs worked. after cutting 6 of the 10 segments have issues. For example;
- Blue not working on LED 0
- LED 0 not working at all
- LEDs 18 and 19 not working
- LED 1 green not working, LED 19 not working
- LED 18 and 19 not working.

I have been careful when making connections, Not connecting to a live circuit, GND first.


Obviously I have damaged them somehow. Anybody know how? Can you damage them if the solder it too hot (I was using about 340 degrees but reduced it to 240 just in case).




engiboy11

Give some more information on

- Blue not working on LED 0
- LED 0 not working at all

The two statements are contradictory. LED 0 can not be blue if it is not working at all.

MartynC

Each comment refers to a different 20 led mini strip which where cut from the initial large strip. The initial large strip (1m of 144 LEDs worked fine).
On 1 strip Blue is not working on LED 0. On another strip LED 0 is not working at all. etc





Helmuth

#3
Dec 02, 2015, 07:58 pm Last Edit: Dec 03, 2015, 10:14 am by Helmuth
Quote
Anybody know how?
Please show us a photo of your soldered joints.

Quote
Can you damage them if the solder it too hot
Yes. It is beside the temperature also the time you apply the temperature that matters.

Your description tells me that only the leds close to the joints are affected?!

engiboy11

Ok, I have dealt with this kind of a problem in the past a few times and might be able to help you out.

So, when you say that 6 of the cut strips are not working as expected, I am assuming that you are testing them individually and have not made the matrix yet, correct?

Do you have access to an oscilloscope?

If you look at the datasheet of the ws2812b, you will see that the led has 6 pins, out of which you can see 4 contact pads coming from each LED on the strip. One of those pads is dataout( probe till you can see it on the oscilloscope or simple eliminate all other pads by probing them), and one way to figure out if the strip is damaged is to examine if the data going out of your digital arduino pin is being reshaped by every LED and then being transmitted to the next LED.

I am fairly certain that the problem lies not with the entire strip but with an individually affected LED.

MartynC

yes, it is individual LEDs that do not work. In a strip of 20, the first LED will not work but the other 19 do.

I will try to upload some photos this weekend.

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