I have a bunch of Noma LED Christmas light strings, each with 70 LEDs. With one string, exactly half of the LEDs don't light up when plugged into the AC. The whole string used to work, and it's only about a year or two old.

My understanding is that Christmas light strings like these are often two independent circuits, with fuses built into the plugs at either end. I notice that most of the way through the string there are three wires—but at the middle-point of the string, there are only two wires joining the 2 halves. So, this idea that there are actually two independent circuits seems to make sense to me. There must be a fault in the 2nd half of the string, or the fuse in that half must have blown.

My question is this:

Has anybody ever tried repairing this kind of LED Christmas light string? Is it worth it to try replacing the fuse? (Of course, it would only make sense doing so if there wasn't some other more serious fault in the circuit—but how would you debug the cause of the failure?)

The plug at the end with the problem looks like it has a small catch you could push in with a small screwdriver, but it appears almost impossible to pry open the plug without damaging it. Even if I did get the plug open and find the fuse, I'm wondering if the fuse is even some standard size or type that can be readily replaced. Is this just a one-shot type of fuse?

Failing repairing the 2nd half, I might cut the string in two and just insulate and seal the cut end with heat shrink. Has anybody done this to a broken string of LED lights?

⟐ Commented December 29, 2024 at 15:00 MST

We have at least 50 or more strings of lights on the house and garage and garden shed. There is maybe 20 or strings of lights on the trees around the yard and all the ornaments and blow ups have lights. We bought high end outdoor power bars and ran them all to a control panel an electrician friend had built for us.This in turn is wired into the main fuse panel in the garage which has heavy power as my husband puts it . He has a work shop in the garage with lots of power tools. So the question of power should not be a problem but it is.

Heres our problem when we turn on the lights they are very dim . We have tried shortening the extension cords taking off lights we've tried cutting the number of lights down but the only thing that seems to work is taking the LED lights out of the equation. when we take out the led and leave only the older strings of lights everything works fine but when we use the newer ones it all dims out. hes out there now trying to hook up only the led to see if they will work alone has anyone had this problem and can you tell us what we can do to run both the old lights and the new.

UPDATE :

Paul's still out in the yard without any luck yet hes tried the control panel removal , didn't work, he's now checking each strand of lights to see if there's just a bad strand. will keep you posted please more ideas would be appreciated.

⟐ Answer accepted April 11, 2016 at 4:22 MST

I know that LEDs are DC. But these work off of house current/voltage.

Is there a way to change them to DC, where I can connect them to a battery or some other power source? (Cut the plug end off or something?)

⟐ Answered August 07, 2022 at 20:06 MST

⟐ Commented February 19, 2026 at 5:31 MST

⟐ Commented December 07, 2021 at 19:56 MST

⟐ Answered February 11, 2025 at 14:09 MST

⟐ Answered January 07, 2024 at 12:43 MST

We have a 5 foot deer with at least 1000 LED lights that stopped working. The transformer is putting out 24.2 volts - supposed to be 24. The deer has 2 connectors inside, probably splitting the line into thirds. If I disconnect either one, there are 24.2 volts coming out of each. The bulbs are sealed - not able to be unplugged or taken out. Why would the lights not be on?

⟐ Answer accepted January 12, 2026 at 14:18 MST

Some bulbs have 2 wires and then in the middle where the burn starts that bulb has 3 wires.

How can I fix these?

⟐ Commented December 16, 2020 at 9:59 MST

This year, the bottom and top section’s strings light up, as well as the middle string of 3 in the middle section, but the 1st and 3rd string of the middle section won’t light up. I can see that the current is running just fine throughout the tree as the bottom and top lights work. Any ideas why 2 of the middle string of lights aren’t working? And how to fix this?

Thank you! Please help my family save Christmas!

⟐ Answer edited September 08, 2019 at 7:51 MST

⟐ Edited December 27, 2023 at 15:14 MST

The light strings that are working at the end of the season are coiled up and placed in totes and placed in a storage shed.

When we have pulled them out and started stringing them we discovered quite a few strings have only half the string working. I have read where the LEDs are steel and can rust and can create an open circuit.

I believe that open circuits don't damage anything else. But, a burned out LED will likely be shorted increasing the current in the circuit. That would be the same as removing the socket from the circuit and soldering the resulting leads together.

Now...Current in a circuit is the same throughout the circuit. So...if you removed or had several LEDs burn out and short, than this circuit would have higher current flow...and if this string was the first in a daisy linked chain of strings...would this endanger the entire length of this chain?

Some of our chains are 20 strings long and some are 40 strings long.

Supposedly this was per manufacturer. So would the higher current flow of the first string raise the current for the entire chain endangering and shortening the life of all those strings?

⟐ Answered November 29, 2024 at 5:56 MST

These exact lights: https://www.homedepot.com/p/Home-Accents...

See a picture for a diagram of the wiring. But here is my best explanation:

1. I run one full-length string one on gutters
2. I needed more, so I added the 2nd to complete the top and trimmed it to fit the required light area
3. I connected this to a 6ft. extension cord
4. the 6ft cord has 2 separate extension cord that runs off it.
   1. 22' extension cord to the 3rd light string in the connected series around windows #1
   2. 41ft. Extension cord to the 4th light string around window #2.
5. All lights work except string #2 in the series….
6. String numbers 2, 3, 4 are all trimmed to the needed length, and String #2 is greater than 20 bulbs.
7. Lights work on all strings EXCEPT #2...

I tried swapping the led bulb in the single socket to test since it cant be the fuse or light strings #3, and #4 would not work correct?

And nothing happens when testing different led bulbs, not quick burn out, or even a little bit of light. I am so confused...

EDIT - sorry I forgot the pictures! - hopefully, these annotated ones will be more helpful anyways? Thank you all for the help!

⟐ Commented December 13, 2021 at 12:49 MST

⟐ Commented January 26, 2025 at 19:56 MST

⟐ Answered August 19, 2024 at 19:44 MST

Using 3 AA batteries in series (4.5vDC) the battery box has a sequence button for various modes. It also times out after six hours and the batteries last about three days.

I decided to connect a 4.5v dc transformer to the two feed wires.

Surprisingly only two of the four colours lit up.

Reversing the polarity lit up the other two colours.

there are only two output wires and connected to the box it was possible to have all colours continuously lit.

Can it be sending tiny bursts of alternating current in DC…… yes I know it makes no sense but I am baffled!!!

⟐ Answer edited December 16, 2023 at 7:30 MST

⟐ Answered November 20, 2022 at 8:30 MST

I have a string of C9 LED Christmas lights that are not working.

I used a light pro device to test the electrical current going to each bulb and I believe I found the culprit. The electrical contracts were coming out of the socket! I tried putting them back in but that did not solve the problem. I touched the exposed contacts to the bulb wires (tried both sides) and that did not work either. I can plug another string into the end of the malfunctioning one and the second string works just fine. I also checked the fuse and that is fine. Checked the bulb and that is fine too. I am thinking I just should bypass this particular socket. Is that possible? If what wires do I cut and splice together? See image. Thanks for the help!!

⟐ Answered November 18, 2022 at 1:07 MST

I have a fariylight string which was working with a solar panel, however it stopped working suddenly, I don't know why, I opened it, and there is a battery that gets charged and then is used to supply the lights,

now what I want to do is, remove the solar panel and directly connect the lights to the battery,

I tried that, now I have two wires from the light, I connect either of them to the battery but it won't work, I used a tiny resistor from another device but it won't work too.

I watched a video where I can connect the two wires to a usb but it didn't work too.

I don't know if there's something wrong in the way I do it. I don't know if there is a positive wire and negative one but I've tried both and it won't work.

what should I do? and know that I've got no experience at all in electronics but I'm trying to.

⟐ Answered October 20, 2021 at 0:37 MST

⟐ Answered December 12, 2020 at 13:11 MST