Light string goes from bright to very dim towards the end of the string

SpeedWalker

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Nov 6, 2011
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Hi, I am stuck here in NZ and have encounted a problem with my incandecent light strings (Ring Grip and Arlec) which I've had for a few Years. They start off Very bright and as you move along the string the lights get dimmer and dimmer to the point that they are hardly going towards the end.

I have randomly tested end bulbs at the start of the string and they work well and share the same level of brightness as the ones I've replaced at the start to test they bright bulbs from the start of the string are very dim when I replace them at the end of the string.

Also I have used compatable transformers with no success.

Can anyone help as this is not just one set but affects 12 of my sets so they make up a significant proportion of my light display.


Cheers

Daniel
 

SpeedWalker

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Yes, thats the problem, is like the beginning of the string is taking more of the voltage (brighter than usual).

Cheers
 

David_AVD

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The only thing that I can think of (assuming they were actually good last year) is that you have broken wire strands in the cable, effectively increasing the resistance along the way.

You might want to post a picture of the strings in question in case that gives a visual clue.
 

wjohn

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May 22, 2010
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see if you can test the voltage at the start, and at the end of each section of the length of the string.


You'll know where the end of the sections are where the wire strands go from three wires to two wires.


Use a pin to pierce the wire and measure the voltage across the two wires.


The transformers put out 24 VAC, and you should see ~24 volts at each section
 

AAH

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I'd be wondering if maybe you've extended the strings and that they are now carrying maybe double the usual current and as such there is a significant voltage drop. I've sorta solved the problem before for a mate who had a similar problem with garden lights. I ran a suitably sized figure 8 cable to the far end of the string.
 

SpeedWalker

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Hi, I will get a volt metre tomorrow. I am under the belief that there is a voltage drop but it perplexis me as to how this would occour. The cable is aged but not damaged. AAH could you please describe where you soldered/connected the "suitably sized figure 8 cable". The lights are 24v.

Its is really fantastic to get ideas from others even when the answer is staring you in the face. Help its that time of year.
 

SpeedWalker

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Hi all I have measured the voltage with 22v at rhe transformer and 12v towards the end of the string, wow what a drop and it explains all.

However I need to understand the cause of the problem and weather I can fix it? I have used different but compatable transformers with the same result.

I am stumped as this is the first time I have encounted this. Cheers
 

AAH

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If the strings are untouched and they are all going all I can think of without actually seeing and measuring is that maybe the exposed copper has been corroding and as a results you've gained resistance steadily along the string. As it is a string I'd reckon that there is likely to be 8 to 10 globes in series. This makes finding the place to tap into the far end a bit more difficult. Pull a globe near the far end. You'll lose what i expect is the 8 to 10 globes. Immediately between the last lit and the first unlit globe there should be a change from 3 wires to 2 wires and it would then go back to 3. Where there are 2 wires is where to tap in. If you know how to use your multimeter then you can measure and work out the polarity. Alternatively you can use the primitive Pete method and have the 2 wires exposed on the extension figure 8 and 1 of the conductors exposed on the existing strand. Separate some of the strands of the figure so that it sorta fuses the wire to a lower current. Rapidly brush some of the strands of the figure 8 across the existing wire. The lights will get brighter if it's the right polarity and will get dimmer if you're shorting things out. Once the polarity is sorted then solder and insulate with heatshrink or tape.
 

AAH

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Just out of curiosity are the strings the clear style wire and has the wire darkened considerably from brand new? I'm going to have a post/rant about strings of this sort shortly.
 

BradsXmasLights

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I've had multiple incand fairy lights like this. Most noticeable on some 300 light strings, all because they use the thinnest wire and a HoHoHoweak transformer. I cut them in to lengths of 100 and they work fine off a more powerfull transformer.
 

SpeedWalker

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Nov 6, 2011
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Cheers, I did try a 36v Transformer instead of the supplied 24v, with increased brightness but still the brightness was inconsistent across the string. I have had to suck it up and retire the strings as spare bulbs. Bring on the LED's, however I do suffer for an acute case of deep pocket short arm syndrome.
 
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