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bac
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Half of the string of LED Christmas lights doesn't light up

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a bit of a low-tech although seasonal question for you...

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 trying to replace 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/type of fuse that can be replaced? or 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 heatshrink. has anybody done this to a broken string of LED lights?

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Josh Wardell
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Yes, LED christmas light strands are often two independent circuits.

The LEDs are connected in series, so if one is disconnected or somehow failed open circuit, that circuit will go out. Of course the same will happen if there is a break somewhere in the wire.

You could check with a voltmeter to see if you are getting 120vAC out of the socket on the tail end, which if zero would mean a wiring break.

But I think chances are you have one failed LED.

Further testing would mean cutting into the strand.

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oldturkey03
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The small catch in you plug is where the fuses are. You should find two of them in there. I am not sure where you are located but I get my replacement fuses at Walmart and its a lot cheaper and less time consuming to start with that. Give it a try and thanks for the Christmas Spirit....Good luck.

UPDATE

just added an image due to another question about this....

Edited by: iRobot ( ) , oldturkey03 ( )

only 54 more sleeps!!!!! best get all those lights working..

pollytintop,

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Phil Atterbery
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Good Evening to All and may all your lights work. I encountered the age old problem of half the strand not working. I discovered it before I put it up on the eaves. This year I got an early start on my lightscape so I had time to troubleguess the offending strand. I inspected the wire for breaks. Then plugged it in to the wall socket. I removed one LED at a time starting at the plug end. After the sixth LED I was ready to quit. #7 proved to be the problem. The prongs of the LED were misaligned in the base so they couldn't make contact with the socket. I pushed the prongs into position, put the LED in the socket and "bam" the rest of the strand came to life. The whole task took 10 minutes. The best part is that I was able to live up to the expectation of my 7 year grandaugther who was observing the proccess. In her words, "Good job Granpa". I hope this answer is helpfull to someone. Happy Holidays from Phil in Kansas.

+ That just shows that when the going gets tough, the tough keep on trucking.....:-) Happy Holidays

oldturkey03,

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RoddyMacRoddy
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This business of flipping the plug, using oscilloscopes, or noting hz is all indicative of not understanding Diodes. LED's (Light Emitting Diodes) only work with the current flowing through them in one direction... direct current. Alternating Current (your house current) fluctuates or oscillates 60 times a second.. hence "60 hz". In order for your LEDs to wok on that circuit they need half of those oscillations to be eliminated. They also need the voltage to be greatly reduced.... from 110 down to about 5. LED's also cannot be tested like an incandescent string of lights using an ohmmeter because they have no filament. Testing a bring of LED's would require setting up your multimeter as an ammeter, breaking and testing the light string only (not the other two lines.

Because the string is made to work AS A WHOLE UNIT with AC power, the observation that flipping the plug should alert you that this function has been destroyed. The fuse was there to prevent further damage (fires). The fact that you can replace them should also bring with it the caution that you need to find out what caused the failure in the first place.

A shorted bulb in one of your strings most likely caused a failure in a diode that changes that 110v AC to DC . That event likely caused the fuse to blow. Replacing the fuse or flipping the plug does not address the root problem, and my bet is that you will have to toss the string and buy new.

While you are inspecting your defunct string, break into and have a look at an LED. See that the two electrodes inside are different sizes. The large one is the negative side, the small is the positive. There is space in between... no filament. The polarization of the two poles, and not current flow from one to the otheris what makes that space in between give off light. In fact, if the voltage is too high (AC or DC) that space will be violated and the LED will literally "pop its top". Depending on the element in that matrix, you get different colours. Red is the cheapest light to produce. Clear light is one of the most expensive.

RoddyMacRoddy Once more, excellent answer ;-) It's time for you to make a guide for ifixit that shows how to repair those buggers.

oldturkey03,

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busymomiam
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Same problem, new solution. I tried new fuses and still the one end of each string would not light up. So I thought...Since one string has the plug end that won't light and the other has the receptical end that won't light, what if I cut the strings and put the two ends that do work together? Making sure that I connected the one wire that runs straight thru the entire string to the same on the other side and the other wire that goes into the bulbs together I now have a complete string of working lights. Forgive me but...I somehow feel like a genius right now :). And a special thank you goes out to my daddy, who passed away on Christmas Eve in 1981, for letting me tinker in the garage with him when I was a child. And to all a good nighttttttttttt!

Excellent idea, what a cool way to fix things. Welcome to ifixit and hope to learn ore from you. Happy Holidays...:-)

oldturkey03,

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11team
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half a string is better than no string, cutting the 'broken half' off makes sense - as long as the good half still works afterwards

merry x-mas

Thanks OldTurkey. Problem is, in the spirit of this blog, we are attempting to be less wasteful, so trying to fix instead of toss. That is a laudable goal except that (as any stereo repair shop can tell you) parts are simply not repairable. So we are stuck with the conundrum; do we use old, inefficient technology and repair it as needed, or do we buy into the more efficient products and toss them when they fail? I'm leaning to the latter. I have had this string of LED's up for 3 years. Although the string and most of the lights will last forever, the failure of a small component renders the entire string (or large sections of strings) to the garbage.

RoddyMacRoddy,

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RoddyMacRoddy
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I have never seen light strings with fuses in the plugs will have to look again, but what we DO have is light strings with "Fusible Links". These strings may well have more than two light series in them, separated by a fusible link on each end of the series. Imagine a ladder where the legs of the ladder represent each side of a 110 volt circuit. The light strand(s) are the rungs with perhaps 20 lights per strand. At the intersection of the "legs" and "rungs" you have a fusible link. If a short or a break occurs in any of the light strands, one or both of the fusible links will blow, are sealed for life, and are not serviceable. That light strand will be out and the rest of the strands will remain lit. The fusible links are for safety, not for convenience.

Now for a bit more info. If you try to cut out the fusible links or even replace them with a more serviceable unit, you need to understand something about LED's as opposed to incandescent lights. LED's operate on Direct Current (DC) and will only light with that current running in one direction. They would blow up (literally) if applied to 110 volts AC when they are designed for more like 6 volts DC. So in every light base, or as part of the fusible link, there will be another diode whose job it is to create that DC low voltage. To remove that is to invite disaster.

If you have a string failure, best to cut your losses and go get yourself a new one.

This isn't the same thing as testing for bad lights and replacing them. This is quite different. Meantime, I'm gonna keep my eyes open for those one with replaceable fuses.....

Update

I don't see that chris mentioned a single light as being a problem....

As to the fix you mentioned, if there are that many disposed light strings, could you not cut that light out and replace it with a salvaged one. Might be the best solution as these strings are in series. Every light removed increases the amperage of that one string. This will case other failures eventually. The diodes on these things are balanced with the deign load. They do have a "Threshold" that once exceeded will fail, then that whole string will be out.

Edited by: RoddyMacRoddy ( )

A quick search on Google will reveal plenty of sites like this like this or even this one. Multiple references out there, and surely a PITA if the string does not work.Of course here is even a reference to the fuses in the LCD string. This is not to discredit your answer, it is a very good and correct one. There is always more than one way... :-) Happy Holidays..

oldturkey03,

Hi Again We may be talking Apples n Oranges here. Or UL n CSA. I'm Canadian. We may not have removable fuses in our strings...... Fewer fires too maybe but more waste...

RoddyMacRoddy,

RoddyMacRoddy, it is definitely possible :-) Since I am now in the market for Christmas Lights, I will most certainly check on the LCD strings and the fusible links. Your answer is most certainly interesting and very informative. Only good thing is we don't have to worry about TÜV.....:-)

oldturkey03,

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Naoya Nishimura
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I came across a good fixit write-up online by Terry Ritter. Seems like there are lot more problems to LED lights which requires more thinking process.

http://www.ciphersbyritter.com/RADELECT/...

Nish

Good info here. Thanks Naoya!

RoddyMacRoddy,

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Mickey Ray
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I have the same problem. Half of LED string of lights come on -- the other half does not. Unplug and flip plug 180 and replug and the other half comes on -- and the half that did work now does not. There are no bad LEDs. Every one comes on at one time or the other.

Mickey, did you try another outlet?

oldturkey03,

Took lights down and plugged them into a house outlet -- they all worked. Put them back up -- half worked. By-passed two led strings (that were working fine) with an extension cord and the string worked fine. This does not make sense to me. But am going to resist the urge to find an oscilloscope to see what the by-passed led strings were doing to my current. I will be content that, 'it's a mystery.'

Mickey Ray,

Are you using the same outlet whenever you have the half-side failure? If the lights worked fine in a different outlet, check the outlet first. That wiring sounds screwy....good luck

oldturkey03,

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louism44041
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If you get one half to light its not the fuse as one fuse is for both halves

Just verified my above statement. Checked the 2 fuses on the inside of my plug removed one and Bingo, half the string out.

oldturkey03,

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Attari
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I have the same problem and i tried to fix it, my Christmas lights are 120v and 60Hz AC. The problem is when i brought m lights out and plugged them in, for some reason the whole entire light string wasn't working. So i looked at the fuse and the fuse was OK, so then i looked for any bad light and i think i found it. I went to the market to buy a replacement and found out the old bulb was bad. But apparently when i plug it in the lights light up but only half way. So fro not working i got to work but it only works have way. what can i do to fix it. Please inform me by step by step on how i should fix my lights.

Attari have you looked at your plug of the light string. Did you find the small cover for the two fuses that are usually inside the plug? Did you check those?

oldturkey03,

Yes i have checked the two fuses and both are working, cause it's understandable that if the fuses were bad or not there then none of the lights would turn on when you plug it in. But i have looked at the whole string and i can't decide what the problem is, please help me with step by steps instruction.

Attari,

I believe that the two fuses are for the two separate circuits of the light. Check those with a multi meter and see if they have continuity. You may also just go ahead and replace them since they are not to expensive. The other thing that can happen is that you might have more than one burned out lightbulb. Check on here http://www.ciphersbyritter.com/RADELECT/... or Google some more info. It is not hard to do and I am convinced that you will get it accomplished. Good Luck and hope you are having an early Christmas

oldturkey03,

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Attari
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Thanks, but you see i can't replace the whole entire half string. And i do have a multi meter with the positive and negative leads but where do i check (place them) to find out if the circuit is flowing freely

Lets start of one step at the time. Did you recheck the two small fuses, not just visually checked? Does your string have a receptacle at the end? Do you have power at the strings receptacle?

oldturkey03,

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Buzz
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Sounds like one of the strings is only passing dc instead of ac resulting in one half of the string being lit. reversing the plug would allow the dc to light up the other side of the string. Connecting directly to an outlet would allow ac and both halfs would light. Your problem appears to lie in a string of lights before the affected string.

Buzz

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alicegwyn
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How do you open and check the fuses? Is it where the plug is, or the little cylindrical thing near the plug? Both look encased in plastic, with no opening...

Edited by: oldturkey03 ( )

Most of them have a little tab in the plug that you pop open and you should find 2 small fuses in there. Just added an image to my original answer so you can see what I am referring to.

oldturkey03,

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nick
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hmm..same problem. These LED's contain NO fuses and the bulbs are not removable. Half a strand out, flip the plug 180 degrees and the other half is out. This set is in the middle of about 10 sets, and the lights before, and after work fine. screwy..

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nick
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my particular LED's operate on AC (noticeable strobe/flicker in peripheral vision much like an old CRT tv)

I looked at the strand and actually pulled an LED out, and there is in fact, no diode. There is also no in-line box or anything indicative of additional in-line electronics. They also pass 120V AC to the next strand (and in my case, through 10 strands) because they power small incandescent mini light globes at the end.

A friend of mine just put up all his led strands and low and behold there are at least 3 or 4 sets out of 15 that are completely dead. They worked last year and were stored indoors, not abused or damaged.

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werrwe
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this kind of LED christmas gifts 2011 light string? is it worth trying to replace the fuse? (of course, it would only make sense doing so if there wasn't some other more serious fault in the circuit

Edited by: oldturkey03 ( )

9 times out of ten. you have three choices. Get a new fuse, take a good bulb and replace it with the blown one, or just buy a new set of christmas lights they're cheap anyways.

williamcasey80,

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Brian Grittner
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LED lightsets that are used outdoors are prone to water leakage and subsequent corrosion of the LED leads inside the sockets. Pull the LED's out of their respective sockets in the string. If the leads are rusty, the LED's will need to be replaced. Don't try to clean them if they are rusty. The sockets can be cleaned with a bit of WD-40 and a small screwdriver (please do this with the string unplugged). New LED's can be inserted into the holders. Pay attention to the orientation of the LED's in the sockets. There is usually an indicator on the LED holder that shows a "long" side and a "short" side. Place the new LED into the socket with the long wire on the long side, short wire on the short side. Bend the leads back slowly. They are steel and are not as flexible as brass or bronze leads that are common on the older mini-bulbs. Stop by the automotive dept. and buy a tube of dielectric grease. Squirt some of that grease into each socket before you place a new LED into the socket. That will prevent further corrosion. When you buy new LED strings pull each LED out and coat the contacts in each socket with the dielectric grease before you place the string into service. Replace the LED's back into the sockets, push the securing tab down and your new corrosion proofed lights should last a very long time time. Good luck!

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chris
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Ok, so I am having the same problem. Half of strand works, other half is out. The next strand in the series works so I am assuming that it is not a break in the wire and must be a bulb. Would it be the first bulb in the series that is out or could it be any of them?

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robert
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Last night I had the good ole plug them in and 2/3 of the lights do not come on AFTER testing them in the garage. I have found out a couple of useful things. The strands that I am talking about are the C9-100LED's. 1) These starnds are actually split up into 3 sections and a bulb going out will kill that section of the strand. On the 1st section I checked 8 lights before finding the bad one the second was 15 before I found the culprit.

2) the Christmas Light Tester/Repair Gun can test a LED bulb BUT the bad part is that the buld socket is too big to fit inside the opening that over rides the strand and make the rest of the bulbs work.

I hope this helps.

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kcr
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just "cut out" the ones that don't work (since the actual bulbs cannot be fixed). Then reconnect the lines together ( i use the plug that you crimp and then heat to melt the connector to the wire), then insulate with a lot of electrical tape and you voila...done. It will be shorter but it will work.

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robert
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it was easy to replace the bulb every string comes with replacements.

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Bill
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Yep. The fuse is actually a 1.2 ohm 1/4 watt resistor and in the set I hacked is present at each end. There are also two 1N4007 diodes at each end.

The 'electronics' are housed in a heat molded lump of plastic close to each end of the string.

The string of LEDs is on the third conductor, the other two wires are live and neutral (117vac Canada) At one end the leds are fed from the anodes of the diodes each diode connected to live and neutral respectively, the one diode going to the live side also has the fuse resistor in series.

The other end of the led string is fed from the cathodes of the diodes, one diode going to the neutral wire has the other fuse resistor in series. Using a fuse at both ends guards against the diodes shorting and overloading the circuit. Using a double feed from live and neutral powers the leds at 2x the power-line frequency or 120Hz here in North America which makes the strobing a bit less noticeable.

The string I took apart had failed and the cause was dry solder joints at the diodes. The soldering was typical awful Chinese soldering using lead free solder.

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Mark Makarenko
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the same thing happened to me. half of my string of lights was not working. the answer ended up being very annoying and simple. it seems my Nova outdoor lights are susceptible to water infiltration from where the wires enter at back, the water freezes and Severs the contact, causing the lights to go out. it was simply a matter of finding the bulb that was no longer in contact, melting the ice( by blowing into the socket while on my ladder to melt it) and then pluging the light bulb back in. presto we have light! hope this helps and the stops at least one person from Cutting apart their lights. merry xmas!

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doylesee
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i checked each led bulb by pulling it out and looking at the two wires. I straightened several of the wires up so they would get better contact.

Almost to the very end of the string I found one bulb with a broken wire. The plastic that protects the led was loose. I replaced it.

It all works.

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rockyballbuster
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I crawled on the roof, freezing my arse off, and found the last bulb that was still lit. I put a replacement bulb in it to ensure the new bulb worked before I went bulb-by-bulb on the bad ones. MORE lights went out, and I couldn't get them to come back on, even with the known good bulb back in.

SO, since i had an extra length of lights at the end of the run, I just pulled the dead light section aside and rehung the line starting at the lit section.

When i take them down this year, I'll troubleshoot them in the warm garage!

Edited by: rockyballbuster ( )

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mrbill97702
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When only half the string lights up, it's usually because of a single light in the bad section. I've had this happen to me a few times now. I've fixed the problem by individually pulling each light and inserting a light you know is working. You're done with this exercise when you find the bad light and the string comes back to life. If the bad light is the first one you replace, it's an easy fix. If it's last one in the string, you'll be wondering if you shouldn't have just gone out and bought a new string.

The toughest thing about doing this is getting the light covers off to expose the LED. On most of my strings the covers are hard to pop off. I end up with a raw thumb if I have to pop several to find the bad light. One way to avoid this is to get lights with covers that screw off.

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David
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Anyone from Canada on this discussion? I have the front half of two LED strings out but up here we have no fuses or fusible links and the LEDs are not replaceable and the plug is polarized. Looks like the trash for these lights. What the heck is the point of having LEDs that save electricity and are supposed to last 250,000 hours if you can't even get them through 1000 hours? And they are not cheap. They are 2 or 3 times the old incandescants which were a pain when a bulb went out but at least they could be fixed if you took the time. Any ideas before I head out to Canadian Tire?

Odd thing is there are two wires at front end then it goes to three on first bulb so those wires must be good. There's .008 A on them and of course 0 on the third that comes out of the first bulb. And 120 V at the plug at the end. I had a third string with half out but jiggling the wires got the bad half back.

Hi David. Fellow Canuck here. I suspect up here in the frozen north, that we don't have replaceable bulbs and fuses like I see in this discussion. We do have fusible links. Those are the bulges on the cords, or they are built right into the male end. Your frustration is valid. The only savings may be at the meter. Having said that, I have a string up now on its fifth year. After year three the first third failed. I had more length than I needed, so just moved the lit portion and hid the rest..... its still going. Maybe like the first stone in the windshield eh?!

RoddyMacRoddy,

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loadster
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I started down this path because I have a no-name LED set with 50 lights and they all checked good with legacy light tester. Filament light tester will drive the LED bulbs if inserted correctly (trial and error, but they are keyed to go in socket only one way) What the legacy tester will not do is find the break in the 115 VAC on the line because it is passed to the repeater socket. Also the clicky piezo pop-voltage function should not be used because it is designed to activate the shunt in legacy filament bulbs, not LED bulbs.

So I still don't know how my sting is wired or why the voltage seems to be passed down the string but the LEDs aren't getting the required forward voltage.

It does sound like alot of folks have miswiring on their house outlets and should just buy one of those testers that shows their hot-neutral and ground are properly connected. On that note, my string uses two 3 amp fuses in the plug which both test less than one ohm and there are three wires connected to the spades which are not keyed for hot and neutral. As in the plug can be inserted either way. Best advise I got from this web page was go buy another string and keep these bulbs for spares.

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Billy Livingston
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After reading most of the Q & A's here. I don't know why anyone in their right mind would bother to buy these lights! It seems to me that the manufacturers are getting away with daylight robbery.

I recently bought three sets of NOMA Leds and after succesfully testing them ok, spent nearly four hours installing arounf the roof of my house. They worked fine the first time I switched them on but the second night half of one set was out and the next night half of another set failed to light.

What a rip-off!

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Drew
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You know... for all the LED hype, these things are sure a pain in the a**, they're just like the old single wire lights, check bulbs 'til you find the culprit. Some 'progress' !

I wonder if anybody's actually calculated their 'power savings' vs. how many strings they've thrown away and re-bought, to say nothing of the recyclable glass, copper, and plastic in this 'offshore' junk.

Gimme' my old 2-wire 'screw-in's' ANYDAY, 1 -out, 1-in, fixed, ta-da !

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Tim Quick
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Drew's comment is spot on.

The waste associated with manufacturing products that are to be tossed into the landfill in short order is appalling.

After researching the methods used to make these it's obvious LED's aren't going to work satisfactorily in exterior Christmas decoration applications when produced the way they are now. And to do it right the cost will be prohibitive, unless some big changes are made. Don't hold your breath waiting for that.

Controlling the voltage on incandescents makes much more sense. Triacs work.

Edited by: Tim Quick ( )

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Chris
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I'm having a similar issue that I'm not seeing stated exactly here. I have 4 connected strings of 50 LED lights that have worked for the last 2 years. After pre-testing and hanging all 4 strings initially worked. However, after an ice storm I noticed that the 2 last strings were out. When looking more closely, the bulbs were actually on but extremely dim. I replaced the fuses on string 3 (the first string with dim lights) and this did not solve the problem. I then ran an extension cord, disconnected string 3 from string 2, and plugged string 3 into the extension cord. Upon doing this, string 1 & 2 remained lit while now string 3 & 4 also lit fully. When looking at the female end of string 2 (where string 3 plugs in) there are no fuses like on the male end. In fact, the end seems completely incased. Also, these 2 connecters were covered together with electrical tape which should have been a water tight seal.

Any idea what my issue is?

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RoddyMacRoddy
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Hi Chris

Its behaving like strings 3 & 4 are hooked up in series to the female end of 2. The only way I can see this happening is if there is short in that #2 female. (not the #3 male) Any sign of heat in that end? There should be none; LED's draw very little current, and a heavy current draw would create heat. AS you can see from some of the problems above, these things may have fuses in them, but if yours are like mine, the plug end(s) mint contain a fusible link which you cannot repair. Actually, you could IF you had a bad string and you KNEW the plug/fusible link was ok AND that the change-out was for the same number of LED's.

IF you suspect dampness is the problem, you can disconnect string #2 and spray a drier in there (or hydrogen peroxide), then knock that out and put some white rice in a bag enough to encase the end, tying it on tight and leave it for a day. Then try again.

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Chris
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Thanks for the feedback. There is no heat in female #2 and I've dried drying it with no success. You are right in that I cannot get into that end at all to discern and/or repair the issue. I'm not going to the trouble this year since the lights are already on the house, but next year I'm just going to move string #2 to an end location of one of my light runs.

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Harvey Brown
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with a power tester find the light that is dead, cut the wire on each side and marret the two ends together the string should work fine minus 1 light .i have fixed 10 failures this way

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Danny
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Question : I have a string of lights that will only come on if it is warmer than minus 15 degrees Celcius or 4 degrees above zero Fareinheit . This makes it virtually impossible to get that one section of lights to work unless I decide to do the repair in the non-working environment . Anybody have a light string failure that was temperature related ?

Thanks Danny

Hi Danny LED's are good for sub zero temperatures, so any fault must be in the string. AS you might have noticed in the submissions to this post, many strings have two or three sub-sets in them. If there was a problem with one of those sub-sets, just that set would not light. It seems that your entire string does not light, so I would point to the male end as the problem. I imagine you are plugging in outdoors, so it could be the duplex (Wall plug) that is the real problem. It is possible that the cold is causing the clasps inside the plug to not function properly. Perhaps check that. Replacing that might be a cheap fix. Metal connections made up of layers (Bi-Metal) will move with temperature changes. This feature was standard in thermostats, but may be a problem in your duplex.

RoddyMacRoddy,

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Jim S
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I have a variation on the above problem - I have a (quite) new 200 string LED set, the first 40 are not quite out - they are on but very dim.

Is this still a "one bad bulb" problem somewhere in that first segment.

Jim

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loadster
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On a 200 light set, there are five parallel strings of 40 LED bulbs. Each bulb is biased by 3 volts. If one string is dim, it means the forward current of one (or more) of the LEDs is not passing as designed.

So yes, one or more bad bulbs is an open but may not be a true open like a popped filament in an incandescent bulb.

You should be able to remove the bulbs one a time and measure using a multimeter on diode setting and find one that has high reverse voltage and and also high forward voltage. The good ones will have a distinctly lower forward (pos on anode, neg on cathode) reading. Typically on LEDs the longer lead is anode. Also, if there is flat edge on the plastic case, that's adjacent to the cathode. Finally the anode lead is typically connected to less hardware inside the colored plastic if its visible.

You can do the same thing with a nine-volt battery and two jumper clips. Use a weak battery or make one of the jumpers a 1/4W 100 ohm resistor to keep from overdriving the LEDs. I know, 40 times of doing this makes buying another set attractive. The light guys know this. When you're reinserting the bulbs, it doesn't hurt to gob a little vaseline to keep water off the steel leads which rust.

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Drew
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Loadster, Roddy, Harvey, et al, and Danny,

Danny, you've got another 'Canuck' here, so your not alone in the 'Great White North' !

Bought a bunch of fuses, HAVE a LOT of spare bulbs/strings, learned how to use my 'Multi-meter', have some 9V batteries, amongst others, and resistors too.

Sat down in now warm garage, and 'had at it' !

Discovered that I had current end to end on ALL my strings (except the ones the squirrels chewed the sockets off) from various stores, Costco, Home Depot, Wal-Mart, Rona, Sears, and probably some others, and that ;

1. SOME bulbs CAN'T be removed from sockets, Norma's I think.

2. Bulbs have a 'positive and negative' side.

3. All 'sockets/bulb holders' are different sizes.

4. Those 'bulbs' are REALLY THICK (had to use my VISE to break them open) !

5. Different length strings bulbs all have different 'power needs' to light 'em up.

6. Too MUCH power in a bulb will 'blow' it, not ENOUGH does nothing.

7. Had NO such 'problems' with old 'incandescents' from 'mini-lights' to 'C-9's.

Conclusions ;

A. 'Standardization' of socket size would be nice, like the old incandescent's .

B. I'm sure glad I used 'Home Hardware's SCREW in C-9's when I replaced all my 'main string' big bulb's !

C. Even the newest string of 'C-7' LED's I bought from Wal-Mart that worked IN the store, but NOT at home, are crap. ( Couldn't return them, already threw out box, stupidly, being so 'trusting' 'cause they DID work in the store !)

D. Expensive as LED's may be, they are NOT worth the 'tearing of hair' and increased 'blood pressure' TRYING to get working. Even the Firemen at Vancouver's Stanley Park's 'Christmas Bright Nights' display can't get these LED strings working, and THEIR 'on the clock' getting PAID to try to figure them out ! So 'screw it', off to the landfill they go ! Maybe some Archaeologist in the distant future can figure them out ! Maybe I'll take them to the Gun Club, might be fun using those little bulbs as .22 (or bigger) targets ! 'Recycling' be damned, 'repurposing' as targets is more fun !

E. The 'Chinese/Vietnamese/ whatever, manufacturer's, WITHOUT 'standardization' and 'Quality Control', WIN !

So much for 'LED's save money' ! Gimmie BACK my MANY DECADES lasting incandescent's !

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Bill
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The 'fuse' on some lights made for the north american market is actually a low value resistor which appears to be a 1/4W size moulded along with a couple of diodes into a blob both ends of the string. I did open up a blob and deemed it not worth repairing. The actual failure turned out to be poor soldering and not component failure.

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