How to repair christmas tree lights

How To Fix Christmas Lights

The joyous holiday season is nearly upon us, but there’s one tradition I hope to avoid this year: dealing with burned-out Christmas lights.

Each holiday season I unpack, untangle, and plug in the previous year’s mini lights, only to discover they don’t work. Sometimes individual lights are burned out, and other times the entire string seems dead. Are these lights worth saving, or should I just toss them out and buy new ones?

🔨You love badass DIY projects. So do we. Let’s build some cool stuff together.

I admit that diagnosing and fixing Christmas lights can be frustrating, but with a little determination and a few specialty tools, you can repair most faulty light strings.

How to Fix Christmas Lights

filo//Getty Images

1. Diagnose the problem.

Carefully inspect each string of lights before plugging it into an electrical outlet. If you see cracked or slit insulation, frayed or bare wires, or damaged plugs, discard the string.

Now, determine if it’s actually a bad bulb causing the malfunction or something else. If it’s a smaller light set, it’s likely wired in series: the electrical current passes through each individual bulb in order to complete the circuit and illuminate the set.

The More You Know
  • A Brief History of Christmas Lights

Larger light sets often have two or more circuits wired in parallel, which explains why sometimes just a section of the string goes dark. In most cases, simply replacing one bad bulb will fix the entire set or one darkened section of it.

2. Find the bad bulb, and swap it out.

Locating the one faulty bulb that’s causing the problem can be tricky. The best option is to use either an electrician’s multimeter or a tool specifically designed for repairing Christmas lights, such as the Lightkeeper Pro. It combines a voltage detector, bulb remover, bulb and fuse testers, and shunt repairer in one compact tool.

You may be able to reveal the bad bulb by simply plugging the lights into an electrical outlet. If you’re lucky, the “bad” bulb isn’t actually bad at all. It may just be loose and needs to be pressed down more firmly into its socket.

Also, remove the bulb and look closely at the two tiny wires protruding from its base. They should be firmly attached and not touching each other. Plus, each wire should be laid flat against the outside of the bulb. When you push the bulb back into its socket, the wires complete the electrical connection.

Klein Tools Voltage Tester

$33 at Amazon

Fluke Digital Multimeter

Now 11% Off

$222 at Amazon

Lightkeeper Pro Miniature Light Repairing Tool

Now 14% Off

$30 at Amazon

GE Long String White Mini Clear Lights (100 Count)

$50 at Amazon

You can also test the bulb using the LightKeeper Pro, or a multimeter. If you discover the bulb is burned out or damaged, replace it with a new bulb. Just be sure it has the proper voltage rating or you risk damaging the whole light set.

3. Fix the faulty filament or shunt.

If all or part of a string of lights is dark, the problem may be a broken filament or a faulty shunt. (A shunt is a device that allows current to continue flowing through a circuit by creating a path of lower resistance than the original path. In incandescent holiday lights, shunts are small wires wrapped beneath the filament.)

If a bulb’s filament breaks, the shunt redirects current through the base of the bulb, maintaining the electrical circuit. A faulty shunt may sound like a catastrophic failure, but you can often fix it with the LightKeeper Pro.

Simply plug in the light strand and remove a bulb that’s in or near the dark section. Next, insert the tool into the bulb’s socket and squeeze the trigger to activate a piezo circuit. A high-energy pulse will shoot through the set and after about 20 pulses any faulty shunt should be re-activated. Pretty cool, right?

Gear Up for the Holidays
  • The 8 Best Artificial Christmas Trees
  • The 8 Best Christmas Tree Stands

If you’re still having trouble locating the broken circuit, try using a voltage detector. You can buy one for about $10 or so, but there’s also one built into the LightKeeper Pro.

4. Replace the fried fuse.

If the voltage detector doesn’t find anything wrong, there’s one more thing to try: Check the tiny fuse located behind a small sliding door on the male end of the plug. If the fuse is fried (you can check it with the LightKeeper Pro), replace it with a new one of the same amperage, which should be indicated on the plug. If after all the testing the light string still doesn’t illuminate, it’s time to get some new lights.

5. Upgrade your lights.
Related Story
  • The 10 Best Christmas Lights

If you’re buying new lights, consider upgrading to LED Christmas lights. There are many benefits to LEDs that make them a great choice over incandescents. They’re more energy efficient, last much longer, and can be programmed to display different colors and patterns. Plus, LED lights are more durable and less likely to break than traditional bulbs. Here are some of our favorite string Christmas lights for indoors and out.


Brizled Warm White LED String Lights

$20 at Amazon

Credit: Courtesy


SYLVANIA Mini Clear Christmas Lights

Shop at Amazon


Epesl Fairy Twinkle Christmas Lights

$20 at Amazon

Credit: Courtesy


Goothy Ceramic Multi-Color Lights

Now 23% Off

$23 at Amazon

Credit: Courtesy

🎥 Watch this next:

Joseph Truini

Joe is a former carpenter and cabinetmaker who writes extensively about remodeling, woodworking, and tool techniques. He has written eight books and is a contributing editor to Popular Mechanics. He also appears on the Today’s Homeowner TV show, and co-hosts the weekly Today’s Homeowner Radio Show. Joe writes from his home in Roxbury, Connecticut. 

How to Fix Christmas Lights

It's happened to all of us. We've spent hours during the holiday season perfectly planning and hanging holiday lights on our Christmas tree. Suddenly, we find ourselves experiencing a Clark Griswold moment, and we spend additional hours searching for the source of the burned-out Christmas lights. Rather than giving up and driving to the store to buy a whole set of new ones, here's how to fix Christmas lights once and for all. It's easier and more affordable than you might think!

Find the Source of the Power Outage

These days, most holiday mini lights aren’t meant to last forever. They're only designed to make it through about three seasons tops (about 1,000 to 1,500 hours). But if you find your Christmas lights conking out on you earlier than that, there's likely an easy fix. When you discover a broken strand of lights, try to determine what's causing the lack of juice. Here are the most common causes.

Chewed Wires

Bad news: Squirrels and mice are strangely attracted to something in the wire, and they will go to town on them if they have the chance. If you see frayed or chewed wires of any kind, you should throw them away immediately. We can all agree that it's better to buy a new strand than get electrocuted by rogue wires, right?

Blown Fuses

Behind a small door in the male end of your strand's socket are a number of small silver fuses. These can get overheated and stop working. Whenever you purchase a box of lights, they generally come with a small packet of replacement bulbs and an extra fuse or two. Use a small screwdriver to open the small latch and be careful to not let them fall out when you do. There are electrical tools as well as fuse testers out there that you can purchase to test which specific fuse is the problem.

ehrlif//Getty Images

Light Bulb Connection

Sometimes a fix is as easy as looking to see if any of the light bulbs on your ailing strand aren’t pushed down into the connector enough. If the fine wires on the end of a light bulb aren’t able to connect to the power source, a loose connection is probably your culprit.

National Tree Company Clear Replacement Bulbs

National Tree Company Clear Replacement Bulbs

Now 15% Off

$17 at Amazon

Broken Bulbs

If all is well with your fuses and all the lights are pressed securely in their spots, it’s time to assume that the problem lies with one or more of your light bulbs. Luckily, replacement bulbs are easy to come by and cheap! You can also keep a “sacrificial strand” on hand—any time you need extra bulbs, you can pull them from this strand that's around solely for use as replacements.

It’s the Bulb…But Which One?

You’ve determined that the problem is a bulb. Sometimes you can actually see the very bulb that has stopped working, but on most sets of lights, if one bulb is out, they're all out. Because the strands work on a circular electrical system where electricity flows through all the light bulbs and then returns to the power source, it’s often one bulb (or sometimes several) that ruin things for all of them.

Light Keeper Pro

Light Keeper Pro

Now 14% Off

$34 at Amazon

Thankfully, there are tools out there that can help you determine which bulb is the problem child. One of the most highly recommended tools is the Light Keeper Pro. It’s the Cadillac of bulb testers, having a place to test voltage, fuses, shunts, and even a place to test the bulb to see if it'll light up. If you’d rather not take out every light from its socket, or prefer something without all the bells and whistles, there are mini light testers that you can hover over any light and see if voltage is going to it. Once you find the one without voltage, you can replace the bulb and see if that does the trick!

Christmas Light Tester

Christmas Light Tester

Shop at Amazon

Know When to Get New Christmas Lights

If after all of this, you still aren’t seeing the light (pun intended), then it might just be time to pitch those lights into the garbage and head out for an affordable new set. And going forward, you've got the knowledge to keep those strands juiced up for a few more holiday seasons.

This content is imported from OpenWeb. You may be able to find the same content in another format, or you may be able to find more information, at their web site.

How to fix a garland - Lifehacker

December 28, 2018LikbezDo it yourself

Do not rush to throw away old lights and run to the store for new ones.



As a rule, garlands have a rather simple design and typical faults that are easy to fix even without special skills and tools. But in some cases, you may need a soldering iron and a multimeter. Therefore, you may still have to turn to a familiar radio amateur.

The cause of a garland malfunction, like any electrical engineering, is the failure of one or more circuit elements. Everything is usually repaired by replacing a faulty part, which can be found in another garland or some kind of broken equipment.

Careless handling of the electric garland can result in electric shock or damage to the device. You perform all actions at your own peril and risk. Lifehacker does not bear any responsibility.

How the garland is arranged

Shot: Hands for Hire / YouTube

All electric garlands are arranged in the same way. In older samples, these are light bulbs connected in one circuit that light up or flash when connected to the network. In modern ones, a controller is added to glow in different modes and the bulbs can be replaced by LEDs.

Usually, old or decorative garlands have two wires, or to be more precise, one, which is connected in the form of a ring and twisted. Modern models have five wires. Four LEDs are located - these are branches. The fifth - general - remains empty.

At the far end, they all connect together, and their other ends go into a small box with a button and a plug.

Inside the box is a controller - a small board that contains a chip for creating effects and a few parts. A diode bridge, a capacitor, a pair of resistors and four (or two) thyristors that control the glow of each of the branches with lights of the same color.

Shot: Sergey Neverov, Ace Hardware / YouTube

In the photo on the left, a pair of black parts in front are thyristors. A little higher is the control board with a microcircuit. The barrel above it is a capacitor, and a row of three small parts next to it are diodes. Small black parts with three stripes along the edges are resistors.

In the photo on the right is the reverse side of the board, two wires on the left are mains power, a row of wires on the opposite side are lines of branches of each color and a common one.

How to fix a garland if it does not turn on

Cause 1. Power wire broken

Thin wires are often damaged by breaking at the plug or coming off the board inside the control box.

1 / 0

Photo: Artem Kozoriz / Lifehacker

2 / 0

Photo: Artem Kozoriz / Lifehacker

How to fix

Move the wire at the plug and next to the box. If the garland works, then the problem has been found and all that remains is to replace the cable by disassembling the controller unit.

If not, troubleshooting should start with the power cable. Open the cover, unsolder the two wires going to the board and replace them with a working wire with a plug.

If there is no visible damage to the board, this should help and the garland will work. Otherwise, the problem must be sought in the power diodes.

Cause 2. Burnt diode bridge

Power surges can destroy one or more diodes of the diode bridge. As a result, the board will not be powered and the garland will not turn on.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Check all diodes with a multimeter and replace the non-working ones with good ones. Details can be taken from another garland or found suitable at the denomination indicated on the case.

How to fix a garland if one of the colors does not work

Cause 1. An open circuit in one of the branches

Due to poor quality, the wires can break off either at the board itself or somewhere between the LEDs. In both cases, the circuit opens and the LEDs stop glowing.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Separate the dead branch from the rest and carefully inspect the wire to check its integrity. If it has moved away from the board, strip it, re-solder it and fix it with hot glue for reliability.

If there is damage on the cable between the LEDs, strip the ends of the wire and solder or twist them together, then insulate with heat shrink or electrical tape.

Cause 2. Burnt LED

Low-quality LEDs often light up. With a serial connection, this means the same open circuit as in the previous case.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Finding a non-working LED or light bulb in a serial circuit is more difficult. One option is to ring each element with a multimeter.

You can also make a jumper from two needles connected to each other by a wire, and alternately close the input and output wires on each LED with them. The garland must be turned on. The LED, when closed, all the lights of the branch will light up, and will be defective.

To restore the circuit, a non-working LED can either be replaced, or simply removed and connected the ends of the wires to each other, insulating them. Without consequences, you can throw away up to five LEDs in one branch.

Cause 3. Thyristor failure

If the control thyristor of one of the lines fails, all LEDs of the same color stop working.

Photo: Artyom Kozoriz / Lifehacker
How to fix

You can fix the breakdown only by replacing the thyristor with a working one from another garland or a suitable one at face value. To check, you need to use a multimeter or resort to the following method.

Identify the wire of the non-working branch and swap with one of the good ones by unsoldering or cutting and connecting with a twist. If the defective line then works, then the problem is in the thyristor.

The wires that go to the thyristors are usually arranged in a row at one of the edges of the board. On the opposite there will be only two wires - this is power. It's hard to confuse them.

How to fix a garland if one of the colors glows dimly

Cause 1. A tear in the wire of a branch

Due to a break in the wire inside the wire in the circuit of one of the branches, contact is broken. The current still passes, but it is no longer enough to light all the LEDs.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Carefully inspect the entire branch. Move the wires at the board and each of the LEDs of the switched on garland to determine the damaged place. As soon as you find it, all the LEDs will light up in full force. Next, it remains to restore normal contact by soldering the wire or stripping and connecting it.

Cause 2. Broken thyristor

Due to a faulty thyristor, one of the lines may not have enough current for the normal operation of all LEDs.

Photo: Artyom Kozoriz / Lifehacker
How to fix

This breakdown is treated only by replacing the thyristor with another one. You can check the performance with a multimeter, or by transferring the wire to one of the working lines.

How to fix the garland if it flashes randomly in any mode

Cause 1. Capacitor failure

Drying, leaking or swelling of the electrolytic capacitor causes malfunctions of the controller.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Carefully inspect the capacitor. If it is swollen, darkened, or electrolyte streaks are visible on it, then a replacement is necessary. Examine the case to find out the rating and voltage, and then find an analogue with parameters no less than the original ones. Carefully unsolder the old capacitor and install a new one, observing the polarity.

Cause 2. Broken resistor

Burnt resistors also cause malfunctions in the controller and unstable operation of the glow modes.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Check the resistance of the resistors with a multimeter and replace the faulty ones with working ones of the same rating. If visually the parts are intact, it is still better to replace them to rule out a malfunction.

How to fix a garland if all LEDs are on at the same time and do not blink

Cause 1. Chip failure

Damage to the controller chip causes all LEDs to light simultaneously and without flashing. The modes stop working, and when you press the button, the lights turn on and go out when you release it.

Photo: Artyom Kozoriz / Lifehacker
How to fix

Unfortunately, garlands with such a malfunction cannot be repaired. A working controller from another garland will not work. It is designed for a different number of LEDs and resistance, thyristor current. Therefore, at best it will not work, and at worst it will cause a short circuit.

Read also ⚡️🧐

  • 18 unusual Christmas garlands from AliExpress
  • How to make DIY Christmas garlands: 11 cool ideas
  • 10 DIY Christmas decorations worth making
  • What to give for the New Year - 2023: only the best ideas

How to fix a garland if the wires come off or the light bulb burns out

If on the eve of the New Year you find out that the old Christmas tree garland doesn't work, for example, one color doesn't light up, don't rush to buy a new one. there is a chance to repair the damage with your own hands. Fortunately, the device of these Christmas tree lights is not too complicated, and if you carefully check all possible faults, you can make repairs at home. Next, we will tell the readers of the Sam Electrician website how to fix the garland if the contact wires come off in it, the light bulb burns out, or the modes do not switch.

  • One or more colors off
  • Does not light up at all
  • Broken bulbs

One or more colors do not light up

One of the most time-consuming breakdowns is the case when one or two colors do not work in the electric garland, for example, only red or yellow and blue, as in the photo below. This indicates that, most likely, the bulbs in the corresponding section have burned out.

To begin with, we still recommend dismantling the switch cover, also known as the control unit, and check the reliability of all connections - contacts soldered to the board. We immediately suggest watching a video lesson from a young master, which clearly shows what to do if the wire from the board breaks:

How to carry out a simple repair of a malfunction?

If everything looks in order, then with a high probability it can be judged that the light bulb has burned out. The fact is that modern garlands are designed in such a way that all single-color lamps are connected in series and if any one burns out, the light will go out on the entire electrical branch. To fix the breakage, it is recommended to act as a good old textbook advises: cut the garland in half and ring both sections. Then proceed in the same way with the non-working section: cut by 2 and check again, and so on until the end, as shown in the diagram.

As a result, you will be able to determine which bulb is not working and replace it. We draw your attention to the fact that it is advisable to use this repair method if the electric garland is non-separable, usually Chinese.

To quickly fix the garland with your own hands, you can take a tester and attach needles to its ends instead of probes. With the help of needles, punch through each section of the circuit in series so that the needle passes to the current-carrying core, and look for where the resistance of the section is significantly different. In this way, you can find a breakdown and repair it with less effort.

Old Soviet garlands for the Christmas tree (without box) are more convenient in this regard, because in them, all the lamps are screwed into the cartridges, and you can determine which bulb does not work without a soldering iron and an ohmmeter by elimination - taking a working light source and screwing it into all the cartridges one by one. Another repair method is to use a tester to measure the resistance of each lamp until you find a blown one.

An example of repairing another difficult malfunction:

Why does the Soviet electric garland not work and how can I repair it myself?

Another way to fix a broken electric garland is to check the integrity of the common wire. On the board on one side you will see 5 soldered wires: 4 for the glow of each of the colors and one common. Now, if the common wire breaks, you just need to solder it.

In addition to the light bulb, the reason that one or more colors in the garland does not light up may be a broken wire, which is responsible for just a certain color. This problem most often occurs if there are cats or dogs in the house that chew through the wires while playing. In this case, you need to find the place of damage, re-twist the current-carrying wires and insulate them. It does not hurt to protect the wires from pets after that.

Does not light up at all

If your LED garland does not shine, and you are convinced that it is not the LEDs, then you already need to look at the control unit and the power cord. First, check the integrity of the cord, it may have been interrupted or the contact on the connection to the microcircuit has broken. After that, check how all the contact connections are soldered to the board. For example, in the photo below, one of the wires burned out. If everything is working, then the board has burned out. You can, of course, buy a new garland if this one was cheap Chinese, but if you want to fix the product, now we will tell you how to do it.

Instead of a standing control unit, you can use a starter from a fluorescent lamp at 127 or 220 Volts (the difference is only in the flashing speed of the bulbs). First, check how the LEDs are connected. If it turns out that the extreme elements of the groups are interconnected by anodes, you will have to redo the circuit and connect the LEDs with cathodes. This is due to the fact that for normal operation of the starter, the voltage to the anode must be supplied through a 5-watt resistor with a resistance of 15-20 kOhm. In addition, diodes will also have to be included in the circuit, as shown in the diagram below. Diodes are needed in order to pass through the reverse current of the network. This is how you can remake and thereby fix the LED garland with your own hands at home.

As you can see, you will have to work hard to repair the product, so if the electric garland is Chinese, it is better not to waste time and buy a new one. We talked about how to choose a garland for a Christmas tree in a separate article. By the way, it is recommended to convert it to a starter even if the garland does not blink or does not switch modes and the reason for this is the controller.

Please note that if it is the LED in the Christmas tree diode lamp that burns out, after which the entire section does not light up, you need to solder the serviceable element strictly observing the polarity!

Broken bulbs

If one or more bulbs are broken and you want to repair the product, we recommend that you simply replace the damaged light source with a new one. We draw your attention to the fact that the replacement should be done only when the power is off, so as not to get an electric shock. In this, of course, unbreakable lamps are better, because. such a defect bypasses them.

If you don't have a spare microbulb on hand, you can safely cut the broken one and connect the wires without it.

Well, the last thing I wanted to say is that if your tubular garland (duralight) does not work, try visually and with a tester to find the problem area and cut it out in the places intended for cutting (marked with scissors).

Learn more