If you're new to Christmas lighting this season, one thing that you're bound to run into at some point is a bad pixel. It’s a part of the hobby, bad pixels happen to everyone. But troubleshooting it and dealing with it can be annoying and confusing if you don't know the right steps to take.

In this article I’ll walk you through defining a bad pixel, finding and diagnosing, troubleshooting, and finally repairing.

What makes a bad pixel?

The first thing we need to do is define what makes a bad pixel. So a bad pixel can manifest itself in a few ways on a string of pixels. If you're new to this, you may not know that pixels pass data along the line, and every pixel actually regenerates the data to the next one.

So when you have a bad pixel, that means somewhere along your string of working pixels will be a pixel that is not working, and then all the ones beyond that are not working. That is the most common type of bad pixel, where there's been some sort of electrical failure in the pixel, maybe it was the cabling, or something on the circuit board - doesn't really matter.

Finding and Diagnosing a Bad Pixel

Now in terms of how this manifests for the pixels, you may see a few different things happen. If you were running a sequence or running a test mode and one pixel went bad, maybe you wiggled the wires and you know it went bad at that moment, then the pixels downstream beyond it are going to freeze.

If you unplug and plug that string of pixels back in they'll do one of a few things. They may get power but not data, in which case they might turn a static color like blue.  Sometimes the first pixel will light up and not the rest. Sometimes nothing will happen at all. That can be a quick troubleshooting indicator, if something looks like it’s frozen, unplug it and plug it back in – do those pixels come on and respond or not?

Another failure point could be missing a color. For example, if you’re running a test mode with red, green, blue, you might have a pixel that is missing a color. So it has red and blue but it doesn't have green. That's going to be a different type of failure because that's a failure of the LED itself. This is less common but I've seen it happen. 

Troubleshooting

In terms of troubleshooting, once you've identified what you believe is a bad pixel there's a few steps I like to take. Notice I said “what you believe is a bad pixel” - you might see your pixel string stop and then some pixels that are off and not responding. That could be a bad pixel, but it also could be something that's gone awry in your configuration, controller settings, smart receivers, etc. and you want to weed out those other options.

What I like to do when my light show is running, if I find a problem once things are on the house, is to count along the string to find out at what pixel number my pixels have gone bad. First and foremost, if it's at pixel 51 or 101, something like that, or if it's the first pixel or the last pixel or two of a prop, the chance of it being a configuration thing is going to be slightly higher.

But you can count starting from your controller, find out at what number the pixels stop working in the string of lights, and then I plug that prop directly into a controller output that's controlling at least that many pixels.

So if it's 40 pixels in, I look at a prop that's fully working, unplug that prop from the controller and plug in the seemingly broken prop. Because then I know everything else is going to be good and it should be running a sequence or a test mode. If it is definitely lighting up at least as many pixels to get past what appeared to be bad, that'll begin to show you whether it's actually a bad pixel or something else.

Testing tools

 Testing tools, like the Falcon F test, allow you to set a number of pixels that you want to light up, and it will light up that number. I can just plug it in and generate data for X number of pixels and see if it lights up or not. This eliminates the possibility of the problem being with xLights, FPP, controller configuration, smart receivers, cables, extensions, any of that stuff.

The amount of times that we talk to folks who replace a pixel and then find out that it's a configuration issue – it happens a lot. It's frustrating to replace a pixel and then realize that wasn't the problem! You don't want to do that, so I definitely recommend using something like this F Test or one of the little Bluetooth pixel testers to light things up in a test mode that's outside of any controllers or anything that has a configuration to it. That's going to make sure that you're actually sending data to the pixel.

How do you replace a bad pixel?

Once you've determined that the pixel is actually bad, what do you do to replace it? CLICKITS by Experience Lights are the easiest way to splice pixels, save yourself time and frustration, and keep it weatherproof, so I highly recommend those, and we sell them here at Above AVL!

The basic guide is to find the last pixel that’s lit up in your string. Assuming it’s a typical failure where there’s a last one that’s lit up, then everything downstream is off, you want to cut the wire and replace BOTH the last one that's lit up, AND the one after it, the first one that’s not lighting (or stuck on a static color).

You always replace two in pretty much any circumstance because you don't know whether the failure is at the pixel that's not lighting up, it could be on the circuit board, it could be at the LED, it could be where the wires meet, but it also could be where the wires leave the previous pixel, and that's why we replace two.

Now if you have a pixel that lights up two colors but not the third, and you've figured out it's not a controller issue, it's not a data issue or power, something like that, then in that case you can technically only replace that one pixel because literally that's the LED failing. The electronics are working, they're passing data along, they're lighting up that pixel with everything else, just the LED in that one pixel failed. Or do like I do, most of the time when I've run into one like that I just leave it alone, but you can replace just a single pixel. 

Replacing a Pixel with CLICKITS

We've got a great how-to video on our Youtube channel for CLICKITS: The Best Way to Fix Pixels, and a much more detailed blog post about CLICKITS and other methods to fix pixels, so I won't go into too much detail here. You’ll need a pair of wire cutters, the CLICKIT product, and pliers.

Basically, you cut the wire on either side of the pixel(s) you're replacing, and push the wire firmly into the CLICKIT, you don't have to separate the wires or anything like that. Then squeeze it closed with a pair of pliers. Repeat on the other side. They are a little more expensive than Scotch Locks and other solutions, but they are so worth it. When it’s 30 degrees outside during display season, it's cold, maybe wet, and I’ve got to replace a pixel, I want to do the easiest thing possible. With CLICKITs I don’t even need to take my gloves off!

I hope this guide has taken some of the mystery and frustration out of troubleshooting bad pixels this season. Need to add or replace strings of pixels for your display? We can help you with that at Above AVL.

And If you're looking for more support and detailed tutorials on all aspects of Christmas lighting, we'd love to have you join us at Learn Christmas Lighting Academy.