Lighting up Christmas: The quick fix for broken light sets

The LightKeeper Pro, from Ulta-Lit Tree Company, is a tool that repairs most sets of malfunctioning miniature Christmas lights.

The LightKeeper Pro, from Ulta-Lit Tree Company, offers a quick solution to repair broken strands of Christmas lights. The gadget's quick fix trigger can illuminate dead lights with the squeeze of a trigger. Theresa Bourke / Brainerd Dispatch

Nothing ruins the excitement of decorating for the holidays quite like a malfunctioning string of lights. I’ve definitely made the mistake of putting a string of light on the tree or hanging them around the windows only to find they don’t light up when I plug them in. I don’t always think to test them out again because, hey, they worked last year, so they should be good, right?

Unfortunately that’s not always the case. Fortunately there’s a tool to help.

The LightKeeperPro from Ulta-Lit Tree Company is a handy little gadget designed to repair light strings with defective bulb shunts.

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As defined by the U.S. Department of Energy, a shunt is any device that allows an electric current to continue flowing through a circuit by creating a path of lower resistance than the original path. In miniature incandescent Christmas lights, the shunts are the little wires wrapped beneath the filament. Most light set failures occur when an individual bulb shunt fails to energize.


If just one shunt is faulty, all or part of a string of lights may not work, as miniature light sets are wired in series, and electricity must flow through each bulb to the next. A set of 100 miniature lights, for example, consists of two strings of 50 lights, meaning one half may work while the other does not.

The plastic gun-shaped LightKeeperPro features a “Quick Fix Trigger,” which connects to a bulb socket and, with the squeeze of the trigger, sends an electrical pulse through the light set, finds the bad bulb and fixes the shunt to allow the light set to work properly.

I received a LightKeeper Pro to test out this year, and I got varying results on different strings of lights.

I first tried it out on a half-working string of lights I had. I know for a fact they all worked last year, but that’s neither here nor there.

Defective sets of Christmas lights can be easily repaired with the LightKeeper Pro, a tool from Ulta-Lit Tree Company. Theresa Bourke / Brainerd Dispatch

I tried the Quick Fix Trigger method but to no avail. I then switched to the audible voltage detector, another feature of the LightKeeper Pro that helps to find the source of the failure. While holding down a button and pointing the tool at the base of each bulb, the LightKeeper Pro will beep to indicate if the socket and bulb are working properly. As I moved down along the string of lights, I ran into one bulb that caused the LightKeeper Pro to stop beeping. That meant I found the issue. I took that bulb out of the socket and used the helpful bulb tester on the top of LightKeeper Pro to test the bulb. It turned out that bulb wasn’t working, so I replaced it with one that was. This method, however, still didn’t fix my problem.

Thanks to the friendly staff at Ulta-Lit Tree Company, I spent about 45 minutes or so on a Zoom call with Linda Barrientos, the sales and marketing director, to see if she could help me along. With Barrientos’s help, I was able to find and fix a couple other issues in my light set, including loose wires in some sockets and more burnt out bulbs. After fixing various problems, I tried the Quick Fix Trigger again and managed to get the working set to light up for about half a second. We rejoiced briefly before scratching our heads ahead.


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Because my light set is at least a few years old, we came to the conclusion that I likely have more burnt out bulbs that need to be replaced. Unfortunately I didn’t have any more spares on me for that set, though, so I’ll have to pick some up and set to work again.

I also tried the LightKeeper Pro out on two defective light sets Managing Editor Renee Richardson was about to throw out. With the Quick Fix Trigger, one of the strands lit up almost right away, while the other set regained some but not all of its illumination. While some bulbs stayed constantly lit after the first couple squeezes of the trigger, others went on and off with each click. This issue, I soon learned, arises when the LightKeeper Pro attempts to repair a bulb but cannot. Those bulbs need to be replaced in order for the set to work completely. I’ll leave that to Renee if she wants to take the time to get some spares. A helpful hint from the LightKeeper Pro website is to take the light set into a dark room and mark each bulb that flashes with a piece of tape to determine the culprits.

The LightKeeper Pro works on a variety of lights, including icicles strings and even pre-lit Christmas trees.

While it can fix about 95% of light sets, as defective shunts are the most common cause for failure, what it can’t fix are blackened bulbs. If one or two bulbs goes out on a string of lights and do not get changed, those defective lights begin to add more voltage to the working bulbs. The illuminated bulbs will then have to work twice as hard to light up and will burn brighter, causing darkened or black rings on the glass. This sort of issue, known as a cascade failure, happens over time and can only be repaired by replacing all the bulbs in the blackened section.

But wait, there’s more

Upon arrival, my LightKeeper Pro came with working batteries already installed and had a couple other helpful features.

Ulta-Lit Tree Company includes a battery tester with its LightKeeper Pro Christmas light tool for customers to be sure all their batteries are in working order for the holidays. Theresa Bourke / Brainerd Dispatch


It has a small compartment in the handle to store spare bulbs (which I’ll definitely use when I get the right spares) and comes with an LED headlight on the front, helpful if doing repairs. The three-way bulb puller on the top of the tool helps easily pull tight bulbs out of their sockets. And when buying the product from , the order also includes a universal battery tester at a total cost of $29.95 for the two tools. When the lights in my little fiberglass Christmas trees started to dwindle, I used the battery tester to determine which batteries were to blame so I only needed to replace a few.

Ulta-Lit Tree Company also makes an LED Keeper to repair strings of the LED lights. This tool is available on the company’s website for $35.

If you need a quick fix and don’t want to wait for shipping, both the incandescent and LED tools are also available at several retail stores, including Ace Hardware, Menards, Home Depot, Target and Walmart. They can also be found on Amazon.

And if you’re like me — an apartment-dweller with a fake Christmas tree who misses the smell of a fresh evergreen — Ulta-Lit Tree Company makes two ScentKeeper products. One is a classy-looking, fresh-scented ornament that hangs on the tree and gives off that natural tree scent. The other is a spray to keep not only the tree, but the whole house smelling fresh and festive.

The ScentKeeper ornament, from Ulta-Lit Tree Company, is a fresh pine-scented ornament to make artificial Christmas trees smell like the real thing. Theresa Bourke / Brainerd Dispatch

My review of the LightKeeper Pro is a pretty basic overview. For more information, step-by-step directions and instructional videos, visit .

And next time you have troubles with your Christmas lights, hopefully these tips will save you a trip to the store for new lights and some unneeded holiday stress.


THERESA BOURKE may be reached at or 218-855-5860. Follow her on Twitter at .
Theresa Bourke started working at the Dispatch in July 2018, covering Brainerd city government and area education, including Brainerd Public Schools and Central Lakes College.
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