I have a set of LED Christmas lawn lights that got burned out (along with quite a few other lights) in a hug rainstorm 2 years ago. It rained so much, the plugs were under water. I've repaired/replaced all the other bulbs/ decorations that were damaged. I am down to one set of lights. These are color changing LED lights (in which I replaced as I still haven't been able to fix). The lights themselves survived but the plug and an electrical item, either a resistor of some sort or rectifier(?) didn't survive. I tried to open it up but being a NEWB with electronics, I don't know what it is. I've written to the seller on Amazon, and they sent me a replacement item but it isn't the same and it didn't work. They think it is a full wave bridge rectifier but when I search those, none look like what I have. I've included a pic of it (and the box showing the power requirements). The plug has the typical 2 small fuses (3V) in it and I've tested the lights using a 9V battery before, in which they do light up (not as bright but close). These lights are very nice, that is why I want to get the set working again if I can. I am hoping someone here can identify what the thing is that is burned out (so I can get another one). Thanks

My guess, its the color changing circuitry/low Dc voltage converter.

Ie the string is now junk.

I agree

A full wave rectifier converts AC to DC. It will also pass DC voltage, but with a voltage drop going over the diodes. No idea if that's what in the green molded thing

Where did you apply the 9v battery?

Does it have to be an AC to DC converter or rectifier and not just a voltage regulator? A lot of motorcycle and lawn mowers have generators that produce AC output then regulate it to 12 volts AC to power lights for instance. They will add in a rectifier if they need to re-charge a battery with 14 to 16 volts DC. That string of lights only needs 9 volts to 12 volts of any voltage AC or DC to light from the 110v/120v AC that's available. Never saw a voltage regulator that small but electrical tech has advanced. My guess is it's a voltage regulator that regulates AC to 9v or something down to under 15v? Can you check if it's AC voltage on the in side and what type of voltage on the other side? If it's AC on both sides then you'll know.

That cylinder shape around 2 wires covered with plastic looks to me like a
“ ferrite core radio interference suppressor”
similar to the similar cylinders you see on the cord between a keyboard and computer.

It would be good engineering practice to have this ferrite just past the rectifier because the diodes inside the rectifier create little voltage spikes 120 times per second when converting 60 cycle AC to DC.

Was there a larger DC rectifier box between the AC plug and the device shown in your picture?

Palomar Engineers has long sold ferrite “snap on” retrofit kits

https://palomar-engineers.com/ferrite-products/Ferrite-Core-Products-c21312657

I went to Wally World to get a few more strands of lights because some of the ones we put away last year dont work now.

New strands of 100 lights were $2.98 !!!

I hate throwing things away and and am a fixer by nature. But dang! Its not even worth it to replace burned out bulbs!

We wonder why
1) Nothing lasts
2) The landfills are filling up

I like a good deal as much as anyone but how can they make them and ship them over the pond for $2.98. Its crazy.

I hate, hate, hate dealing with Christmas lights, but my life would be miserable if I don't. I really thought the switch from incandescent to LED would make them more reliable, but no. Strings that were working when put away are 1/3 dead ten months later. And yeah, for the price they're not worth trying to puzzle out which bulb to replace. I suppose I could get commercial-quality sets at $5-10x, but that's not happening. Bah, humbug.

For an LED light string? No. Irrelevant and unneeded.

Thanks for all the responses, let me see if I can respond to all:

JCC - The lights still work when using a 9 volt battery to test them, even still change color, so I don't think it is a gonner.

Hoozie.. I put the 9v power to the wires past cylinder, it is one of those led christmas light repair tools, yellow handle device to help find burned out bulbs.

A12 - I have one of those cheap mutli functional tester... can I use that? I am thinking it is DC because the lights works with a 9 v battery in my light fixer tool.

360 - The cylinder is after the typical christmas light plug, which has 2 of the 3v silver fuses housed in it. These kept popping after the water damage, even after weeks of drying out.

Bsharp - yes, that is what it looks like! A rectifier and it says that on the tag on the box. I guess I have to figure what size rectifier I need. I will look at that website!

Wingan - This set goes for about $100, so you can see why I don't want to give up on them yet. They are a really cool light set.

Thanks again all for the input.. I am going to try the noveltylights.com site Bsharp mentioned. Will report back if I get to work again.


The noveltylights site doesn't sell parts or have a technical department, so I am trying some other repair people I saw on youtube...

i fix all my light strings by not putting anything up...............
humbug for me as well !

Just cut it open and find out what's inside.

That would kill this thread and the suspense.

Philly - I already did cut it open, There is another plastic cover over it! (I guess the first makes it water resistant). So after trying to cut the second cover off, which is much harder as it is like it was dipped in liquid plastic, I was able to expose part of it. I can't tell what it is, it would need to be heated up to melt the plastic off. Looking at the noveltylights website, I am about positive it is a rectifier. It looks exactly like the top pic here from Bsharp.

Yep, makes sense that it would be completely potted to keep moisture out (you had one job... )

All that should be in it is 4 diodes. Doesn't look big enough to have a voltage regulator. There's no voltage output from the rectifier when you plug it in, right?

Typically, the LEDs will be in series, or two parallel lines of leds that are in series. Rectified 110vAC will be around 150vDC. Each led drops a couple volts, and somewhere there's a current limiting resistor. 50 leds x 3v each is around the 150vDC they would see. Giving it 9v shouldn't be enough to get them to turn on at all.

But, if they're color changing there has to be something special somewhere? Although that can be built in to each individual LED too.

Looks like this set? https://www.amazon.com/Lawn-Lights-Illuminated-Decoration-Multicolor/dp/B07VMKPN8Y/ref=sr_1_2

I would be tempted to get a full bridge rectifier, and wire it in place...

oops! I read the ad as static but it says on down that the 36 series changes.

Hoozie - yes, those are the lights. The plug isn't anything special, just the 2 small fuses in it, typical christmas light plug, like in the pic above. The LEDs themselves control the color changing. I've contacted multiple Christmas light companies and no one will tell me where they get their supplier gets components from or will provide me any information. Of course they are more than happy to sell me a string of lights! Not spending $25 plus to cut it up and "hope" it will fix my set. All I want is the plug end to a couple inches of wire part the rectifier! There are 36 total, I may have tested with the 9v somewhere along the string but I do remember them lighting up and changing color. Otherwise, I would have tossed them. Yes, the company I bought them from mentioned a full bridge rectifier. Can you tell me how to make one and what components I need?

Well, this link refers to that inline component as a rectifier. So I am guessing that is what it is.

Rectifier?

If the string runs acceptably well with a 9 volt battery, then I'd get a nine volt power supply, splice it into the light string and ride off into the sunset.

Power supply

Is there a cheap set of lights you can steal the rectifier from?

It would be ugly, but something like this would duplicate it.
https://www.amazon.com/NTE-Electronics-NTE5311-Rectifier-Repetitive/dp/B008UTVH5A/ref=sr_1_2

AC goes on the inner pins, and then it has DC out on the +/- pins. (Remember the DC will be around 150v!)

Or, hook it up to a 12v car battery and see what happens. If that works, a 110v to 12vDC power supply would work, and be a lot safer.