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 декабря 29, 2024 at 15:00 GMT-7

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 августа 07, 2022 at 20:06 GMT-7

⟐ Commented декабря 07, 2021 at 19:56 GMT-7

⟐ Answered февраля 11, 2025 at 14:09 GMT-7

⟐ Answered января 07, 2024 at 12:43 GMT-7

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 января 12, 2026 at 14:18 GMT-7

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 декабря 16, 2020 at 9:59 GMT-7

⟐ Answered августа 19, 2024 at 19:44 GMT-7

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 декабря 16, 2023 at 7:30 GMT-7

⟐ Answered ноября 20, 2022 at 8:30 GMT-7

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 ноября 18, 2022 at 1:07 GMT-7

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 октября 20, 2021 at 0:37 GMT-7

Thank you!

⟐ Answer edited декабря 11, 2019 at 19:55 GMT-7

This is a color changing set Blue and white. My first effort was to turn the full set off and then power on with setting at #1 Steady Blue. I then tried the same with setting #2 Steady white. Same result: the one bulb was opposite color from the rest.

Next I tried swapping the problem bulb from first half of string (1st circuit) to second half (2nd circuit) The problem bulb remained opposite in color. I tried variations of swapping while string powered on and when powered off. Same result.

Next I tried replacing the entire 2nd circuit bulbs (25 bulbs) I ended up with 25 bulbs on white (2nd circuit) and 25 bulbs on blue (1st circuit) Because almost all of my replacement bulbs came from a string of 50 lights with severe wire damage (multiple cuts and breaks) I concluded that a single replacement bulb was one state or another and was at a condition opposite the state of the original bulbs. I dubbed a bulb either State #1 or State #2. Therefore in a string is full of State #1 bulbs replacing one with a State #2 bulb would have the effect that I am observing.

Am I wrong? Is there a way to flip the state?

⟐ Answer accepted декабря 12, 2018 at 4:14 GMT-7

When he plugged in the dimmer, th e strip bliked and has turned off. After this, he tried to swap places the strip and energy cable (this time he connected it correctly), but again the strip bliked and turned off, is it in a working state, or is it dead?

I've reviewed the LEDs again, and I've noticed a tiny crack, and a black point on each of them. Here Is an image, where is shown what happened with the LEDs With red I've pointed the crack and that tiny point, and with blue- the resistor (which is before each LED.

P.S. It is a simple LED stripe without any programable chips

⟐ Answer accepted января 04, 2018 at 13:17 GMT-7

⟐ Commented декабря 25, 2023 at 4:34 GMT-7