I did something stupid

As the subject states, I did something stupid. Let me give some back story. I am working on a unique lighting display option, tackling something WELL beyond my skill level as you will soon figure out. Anyway, just starting on the project and I have already broken something.

What I have:

I have a 60 W 5V power supply and several 5M WS2812b 60 LEDs/M DC5V strips. I connected them to the power supply following the recommendations on the Adafruit site (w capacitors and resistors) and had each strip working with Adafruit's striptest sketch.

What I did:

Well, thanksgiving day I decided to work on the project and got everything back out and started wiring it all up again and I accidentally wired the power to the Arduino Duemilanove backwards. OOPS! As soon as power was turned on I got a lovely burning smell, and instantly turned off the power. Being new to this it took me a bit to figure out what I had done.

What I know:

Read online and figured out I fried several portions of the Arduino:
There is no reverse-voltage protection on voltages applied to the Vin connector pin. Current will flow from the GND pin of the ATmega328P back up through the 5V pin, back through the 5V regulator and to Vin. The same thing will happen with the ATmega16U2 microcontroller. Both microcontrollers and the 5V regulator will be destroyed. From 10 Ways to Destroy an Arduino — Rugged CircuitsRugged Industrial Arduino Microcontrollers

What I need to know:

I realize that the smell and smoke came from the LED strips. When I try and light them now with a new Uno the 5M strips with the power connected backwards don't light or a single LED will light. When I try and power the strips at the strip cuts I can get one or sometimes 3 or 4 LEDs to light, but not the whole strip.

My Question:

Are these LED strips salvageable?
Did I completely destroy them?
How would I properly test them?

I can solder fairly well, so I feel like I could replace a damaged LED. Not sure if I could replace the C1 (control chip?) or not.

What else could be damaged on these strips that I need to check?

Greatly appreciate any advice or direction that could help determine if I have completely killed 10M (2 strips) of these LEDs or not.

Thank you

As they use to say, bit the bullet.

So the complete 5M length of the LED strip is dead, even though I can get individual LEDs to light?

The reason I ask is I was going to cut these 5M strips (60 LEDs/M) into lengths of 24 LED strips, so if I could salvage a bit, it would be great.



Unfortunately only testing to see if it works will tell if things can be salvaged, and thats something you will have to try and do.

If I were you I would not try to salvage them. You could get yourself seriously hurt or worse. I suggest that you replace the parts and be more careful next time.

That is what I am trying to determine, how to test the strips.

What is the proper way to test a strip this long on the individual LED level?

If I continue to try and power from the cut joints I assume I would be sending power both forward through the remainder of the strip, but also backwards through the start of the strip.

Won't this damage the C1 ship where the power runs backwards through the strip?

So is there a safe way to test the strip without cutting it up to see if it is still good?

Thanks for the help

First of all, let's review some basics. LEDS are DIODES. They inherently BLOCK current flow in the wrong
direction. What this means is that you fried the WS2812 controller chip, NOT the leds.
There is no fixing that. They're toast.
You CAN however , PREVENT such thing from happening again by putting a series diode 1N4004 in series
between the PS and +Vcc bus but this will induce a 0.7V voltage drop which could be an issue. Alternately , and probably preferably, you could train yourself to always connect the GND first and then measure the power from the PS with a meter BEFORE connecting it to a load. I can't help but wonder if you are using
color coded wires (red for +, black for GND), as it is hard to not notice the polarity when using color coded

Thanks Raschemmel, that makes total sense. This explains why I can get individual LEDs to light, but not the strip.

I am using a breadboard and I had a white wire and black wire that I ran over to the 5V supply. I didn't pay attention to which side the white and black wires were coming from and hooked them up in reverse, so the black wire went to the V- and the white to the V+, which was backwards to how I had used the breadboard. Yes it was a silly mistake and a costly one. I believe I will take your advice to heart and test with a volt meter from here on out. Killed a $30 Arduino and $80 worth of LEDs, so it wasn't a cheap lesson.


Are the LED's addressable, ie is the chip embedded? If it's not and the chips are on the strip, they could be replaced...

Strips are these: http://www.aliexpress.com/item/Mini-Order-5M-60-LEDs-M-5050-RGB-WS2811-IC-LED-Digital-Non-waterproof-Addressable-Color/1561704735.html

Yes, they are addressable.

They have a C1 chip next to each LED, so 300 LEDs and 300 C1 control chips on the strip. These things are tiny, not sure how I would replace them.

I’m an electronics engineering technician. When the engineer gives me a circuit to breadboard, I can’t take
the risk of blowing up parts that took three weeks to get with a deadline looming just around the corner.
I have to make damn sure I check the voltage before I connect power to anything. Not only that, I have
to use a highlighter and highlight each and every connection on the schematic as I make it so as not to
miss any. In addition , I have to ohm out the circuit across the power bus to make sure there are no shorts.
Engineers expect me to know what I’m doing and if I screw up a circuit and blow a deadline and the engineer has to tell his boss why, well, I think you can guess what would happen.

I am using a breadboard and I had a white wire and black wire that I ran over to the 5V supply.

I impose certain protocols on myself to avoid problems, one of which is
NEVER use BLACK for POWER +. so if I were connecting the white and black wires , the black would HAVE
to go to the PS - (GND) at one end and the circuit GND at the other , so no matter what combination of
BLACK and ANY OTHER COLOR I use, I KNOW the BLACK is always GND.
Another protocol I use is when I breadboard a circuit , the component layout mimics the schematic so if
you are looking down at the breadboard , the component locations match where they appear in the schematic, so going back and forth between the schematic and circuit is a smooth transition. Once you’ve
seen the schematic you know exactly where the parts are going to be on the breadboard.
Also, Power is always the upmost bus (furthest from the bottom of the breadboard) and the inputs are
always on the left and outputs always on the right. Of course , almost all breadboards have color coded
power buses so I have to follow that. Positive is always the red marked bus and Negative the blue marked bus. While the above may be a little extra work, when you are pressed for time , you don’t want
to waste time looking for components or where they connect. Being able to “see” the schematic when
you look at the circuit is big plus. I do the same thing on protoboards with soldered components whenever possible.

Totally get it, just not my professional experience. Haven't really wired circuits since high school, which was ages ago. Made a silly mistake and it has definitely cost me.

I am trying to light up these display cases I have for my other hobby. I then want to write code that will refer to a look up table and specifically light up regions of the display case upon user choice. So have a long way to go with this project, and more to learn. Would love to salvage these strips, but it sounds like they are beyond repair as I am not sure I can solder something SO small as the C1 chips.


I once worked with a tech who never seemed to make any mistakes. I once asked how come he never makes mistakes and he laughed and said he's made most of them in the past he already knows what NOT to do and that he catches his mistakes before any one else can see them.

It’s just vaguely possible that your arduino has survived. Have you tried hooking it up to a pc and running something simple like the blink example?

When I connect to a PC I get a Power light and both communication lights on steady. I also get a message from the computer that something attached to the USB can not be identified or something like that. So I figured it was dead. Still working on testing the 5 meter strands.

Hm, the pictures of those strips show the 4-pin WS2812B chips. Those are supposed to be reverse polarity protected. Either the mfg claims are inaccurate, or you got LED strips that didn't match the picture and used the 6-pin WS2812, which is notorious for being fried by reverse polarity.

When I connect to a PC I get a Power light and both communication lights on steady. I also get a message from the computer that something attached to the USB can not be identified or something like that. So I figured it was dead.

OK, so it was a Duemilanove, which uses an FTDI FT232 interface chip. No doubt, this is toast with those symptoms. Had it been a UNO R3, I might have suggested some chance that the Atmega16U2 chip had simply lost its mind and could be re-programmed via ICSP but ...

Still working on testing the 5 meter strands.

As others have pointed out - whatever has completely destroyed the majority of the chips, has most likely damaged the remainder in ways that may not be evident. Nevertheless since they are serial chains, you would have to test them a step at a time by cutting off each one that does not respond when directly connected to the data stream.

I would get a new strip but not throw away the old one. When you have got more experience with electronics you might be able to salvage something useful from it but you are not at that stage yet.

I would get a new strip but not throw away the old one. When you have got more experience with electronics you might be able to salvage something useful from it but you are not at that stage yet.

Which is another way of saying that anyone with a lot of electronics experience is a pack rat and has a stash hidden away somewhere of electronics junk they won’t let their wife throw out no matter how many
times she asks/begs. that they use for practice and cannibalizing (called RECYCLING these days)…

has a stash hidden away somewhere

Hey mine is not hidden. :wink: