Adding LEDs to a project used to be enough to make it cool. But these days, you need arrays of addressable multi-color LEDs, and that typically means WS2812B or something similar. The problem is that while it was pretty easy to test garden-variety LEDs, these devices can be a bit harder to troubleshoot. [Gokux] has the answer, as you can see in the video below.
Testing these was especially important to [Gokux] because they usually swipe the modules from other modules or LED strips. The little fixture sends the correct pulses to push the LED through several colors when you hold it down to the pads.
However, what if the LED is blinking but not totally right? How can you tell? Easy, there’s a reference LED that changes colors in sync with the device under test. So, if the LEDs match, you have a winner. If not… well, it’s time to desolder another donor LED.
This is one of those projects that you probably should have thought of, but also probably didn’t. While the tester here uses a Xiao microcontroller, any processor that can drive the LEDs would be easy to use. We’d be tempted to breadboard the tester, but you’d need a way to make contact with the LED. Maybe some foil tape would do the trick. Or pogo pins.
This is super cool – funnily enough I did something very similar for testing mechanical keyboard switches, even down to using the Xiao micro controller!
What about testing the data out pin? The led may appear to be working, but not output to the next light in the chain.
Could be as simple as driving the reference LED from the LED under test, right?
Would be a small change to make.
Good call, I’ve had a strip of WS2812 LEDs that failed because the DO pin on one LED died.
That’s why there is one LED already mounted. Its input is driven from the output of the tested LED
Well, akshully, it indeed is done this way if you look at the PCB :D
Never push on an LED like it’s shown in the image above. This can and eventually will cause bond wire damage to silicone potted ones. Perhaps starting with the contacts is better to avoid needing such force at all, e.g. by snipping a SIM socket into bits (e.g. JST SCZW) to extract and re-arrange the contact strips.
Samtec z-ray may inspire you to make a more generic adapter until you spot the price tag.
I’ve found the bond wires to be very fragile. I have 36x WS2812B LEDs on an ebike. During 1 year, one LED has had data-out pin failure (which I had to replace), and 3 have lost a single color channel.
Can design a simple clamp that actuates on the legs only.
I’m amazed anybody can be bothered nowadays to harvest LEDs. When one considers how cheaply thousands can be bought it seems a bit bonkers to bother using old potentially suspect ones.
I guess it depends where you live but there’s also the matter of e-waste and waste in general.
It’s definitely not something I would do in a commercial setting but, personally, whilst I understand my time does not have zero value, I much prefer to make, mend, reuse and recycle instead of giving money away.
Plus it gives me an amount of satisfaction to recover value from other people’s thrown away electronics so, yes, I would probably harvest LEDs and add them to the junkbox to be reused or given away
Some of us are retired, low income, and have more time than money. And the satisfaction of repairing or repurposing. Why throw away a strip with 99 good LEDs when only 1 is bad?
Seems really helpful for this use case but what happens if the LEDs are different? Like the test LED functions but different from the standard it’s being compared to? I have some busted digital Christmas lights I’m trying to reverse engineer and looking for a way to go about it.
You could extend the PCB and put different pads further along that duplicate the functionality into a different form factor.