What the Tech: Christmas lights not fully working? This gadget can help fix them

You no longer have to throw away strands of lights just because one bulb it out.
Published: Nov. 23, 2021 at 3:25 PM HST
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HONOLULU (HawaiiNewsNow) - Several years ago when my kids were little, I was trying to hang Christmas lights on the tree and none of them would light up. If you’ve ever strung Christmas lights or plugged in a pre-lit tree, you’ve been there.

Anyway, that Christmas in our house became known as ‘the Christmas daddy said a bad word.’

One bad bulb can keep the entire strand from lighting up because each bulb sends electricity to the next bulb on the strand. When there’s a problem with a bulb, usually a bad shunt, you either have to replace each bulb with the one you know works until you happen across the bad bulb and they all come on.

Rather than doing that, for many years you just had to throw the whole strand away and run to the store to buy more Christmas lights. A relatively new gadget called the Light Keeper Pro was invented to fix the lights without someone saying a bad word after an hour or two.

The folks at Light Keeper sent me a unit to test.

Here’s how it works: Once you plug in the strand of lights and nothing lights up, you remove one of the bulbs with a handy tool built into the device which is basically a plastic gun. Then, take the empty socket and push it into a socket in the Light Keeper Pro gadget.

You’ll then pull the trigger on the device 7-20 times. The Light Keeper Pro sends a burst or pulse of electricity that runs through the entire strand, even past the socket holding the bad bulb so they all turn on. Except for the one bad bulb which you can now identify.

Remove that bad bulb and replace it with another and all the lights in the strand should light up.

That should work but if it doesn’t the Light Keeper Pro has an audible voltage tester. Using another trigger or button on the gadget you hold it down the string until one of the sockets does not beep. Then, you’ve identified the bad socket where voltage stops. Replace that bulb and all should be working.

So, the Light Keeper Pro works and I’ve talked with several friends who use it every year with success. There are directions on the Light Keeper Pro website along with several videos to show how to use the product.

It worked, but I’ll be honest, it isn’t as easy as it looks in the videos and my friends told me ahead of time that it takes some practice.

I took several strands that were not lighting up at all and another strand where only a portion was working. Now, these strands were old and I can’t say for sure that they’ve worked in years. There likely could have been several bad bulbs or something may have eaten through the wires (though I checked that and didn’t see anything).

To get a better idea of whether the gadget works, I ran out to the store and purchased a brand new box of lights for about $3 and plugged them in to make sure all the bulbs lit up.

I took an old bulb and bent back the shunt or wires that go into the socket to receive the electricity and pass it along to the next bulb. Once I put the bad bulb into the good strand and tried the Light Keeper Pro.

The gadget turned on all the lights and the bad bulb stayed dark. Following directions, I replaced the bad bulb with a good one and every bulb on the strand illuminated.

If that doesn’t work for your strand, the Light Keeper Pro has an audible voltage tester where you run the gun down the strand of lights. Good bulbs will beep. When you come across a bulb that does not beep, you’ll know that’s the socket that keeps the rest from getting electricity to complete the circuit.

Bottom line: it works. I should mention that it isn’t quite as simple as it appears in the video. Like my friends who also use it told me, it takes a little bit of practice to get the bulb socket into the Light Keeper Pro to illuminate the entire strand.

That was true for me as well. The Light Keeper Pro works only on mini-incandescent lights which are the most common. For LED light strands you’ll need the LED version of the Light Keeper Pro.

I‘ve found the Light Keeper Pro and most retailers that sell Christmas lights including Walmart, Target and Home Depot for about $20.

Get more details at

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