Introduction
These decorative outdoor path LED lights (white) all failed to illuminate after just a few weeks use. They take the form of 4 mini christmas trees in a line. Poor reviews on amazon suggests this occurrence may be a widespread problem and I could find no repair on the internet.
This brief guide shows how to repair for essentially no cost.
The fault was due to soldering spikes puncturing inadequately thin shrink-fit insulation causing a slight electrical short.
The repair involves finding the fault, pulling the shorting wires apart and fixing them in place with, for example, glue.
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Shows the working led lamps working. There are 200 LED's in parallel with a power supply rated at 3.5V 1.5W, which was confirmed as approximately correct (3.4V off-load).
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In the non working state, the on-load voltage was 1.8v, and using 1W, explaining why the LED's were not illuminating (They need a threshold of about 3v). This suggested there was a slight short somewhere, but nothing was obvious.
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The short was easily found in a string of 200 LED's with a thermal imaging camera. (You don't need one, it just explains how I found the location of fault )
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The red arrow shows here the location of the electrical short, which is where the top bunch of LED's are soldered (two wires) onto the LED string on the spirals.
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There are four such locations which need to be carefully inspected preferably with a hand lens.
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What you are looking for is some slight discolouration around the solder joint or the transparent shrink-fit transparent insulation over it. In my case it was very subtle. Also look for spiky solder which is trying to punch through the transparent shrink-fit insulation.
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If you find a suspect area, tease the two wires apart and hopefully the LED lights will come on when plugged in.
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Use glue or hot wax or some other method to hold the two wires apart.
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No disassembly is required to get the LED's working. Non-illuminating lights may be due to wires slightly shorting and dropping the voltage to below threshold.
Wires just need to be teased apart and glued in place.
The fault was due to poor soldering (or poor electrical insulation given that poor soldering was likely during build.)
