How To Fix LED Christmas Lights

Ever since Thomas Edison strung the first strand of Christmas lights around the outside of the laboratory at Menlo Park, the lights themselves and the technology behind them has changed. Therefore, the process of repairing the lights has also changed. The latest technology used in Christmas lighting is the LED light. This article focuses on LED Christmas lights and how to repair them.

A Little “Light” History

The first Christmas lights (besides using lit candles) were incandescent bulbs. These bulbs, much like an indoor incandescent bulb, consumed a lot of energy and produced a lot of heat. These light sets were referred to as C7 or C9 lights, which indicated the size of the bulb and socket. The lights were screwed into a socket and were usually connected in a series circuit, so that if one bulb blew out, the rest would not light.

The 1970’s saw a new innovation in Christmas lighting technology, the mini light. The mini light is also an incandescent light bulb wired in a series circuit, although it requires a great deal less power and produces far less heat than the C7 or C9. In addition, the mini light contained a shunt at the bottom of the filament electrodes that would continue conducting electricity; even if the filament broke (the bulb blew out). This meant that if one light blew out, the rest stay lit.

The 21st century has brought about yet another innovation for Christmas lighting, the LED. The LED is not an incandescent light bulb but an electronic component; LED is an acronym for Light Emitting Diode. LED lights produce colors that are much stronger than colored glass or dye colored incandescent lamps.

LED Advantages

There are several advantages to using LED lights instead of the conventional incandescent bulb.

  • Their colors will not fade;
  • They only use about 1/10th the power of an incandescent bulb;
  • They have no filament that can burn out or break;
  • They operate without producing a lot of heat that could cause burns;
  • They are rated at about 25,000 hours of use (compared to 1,500 hours for incandescent bulbs)
  • LEDs can be blinked without reducing their longevity.

LED Disadvantages

LEDs do have some disadvantages most of which are related to the unique method by which they operate.

  • LEDs do have a limited life;
  • LEDs have steel or iron leads which can rust if exposed to water;
  • LEDs may exhibit a strobe-like effect because of the way they use electrical current;
  • They could cause Ground Fault Circuit Interrupt (GFCI) breakers to trip;
  • LED light sets do not usually have extra replacement LEDs;
  • LEDs cost more that other Christmas lights.

How Christmas LEDs Work

Fix LED Christmas LightsA diode is a semiconductor with two terminals that lets current flow in just one direction after a target voltage has been reached. LEDs are diodes that illuminate. Since household current is Alternating Current (AC) there are periods of positive voltage followed by brief moments of no power (referred to as “cycles” such as 60 hertz for example). This results in the LED light producing a strobe light effect at 60 Hz which may be detectable to the human eye. Without getting too technical, Christmas LEDs must also have a resistor to maintain proper current levels and there may be other electronic components (to prevent the strobe light blinking effect for example). These are all connected and placed in the pre-molded line plug-in, on the back side of where the fuses are located. Simply put current passes from the house into the plug-in where it passes through the fuses and into the resistors and other electronic components and then out to the LED.

Repairing Christmas LED Lights

Since LEDs do not have filaments and are not hollow glass bulbs that can crack or break, LEDs do not “burn out,” but they can fail. When LEDs do fail, most of the time they result in a short, which acts like the shunt found in mini lights, that keeps the other LEDs lit. Therefore repairs to LED light strands are somewhat limited to wire shorts, breaks, missing LEDs, and failed LEDs.

1.) Examine the entire light strand for any breaks in the wires.

  • Broken wires need to be spliced back together and covered with heat shrink tubing or electrical tape
  • Be careful when attaching lights to surfaces other than a Christmas Tree. A staple gun can pierce one or more wires causing a broken connection or a short

2.) If there are no breaks, slide the panel in the AC plug open and check each of the 3 amp fuses.

  • If there is a break in the fuse filament, replace the fuse

3.) If one LED has failed and the others are still working, replace that LED with the same type LED.

  • If one LED is out but the others are lit, the lights are either wired in a circuit that makes this happen, or the LED has shorted and kept the other LEDs lit

4.) If all the LEDs are not working and you have completed Steps 1 and 2, the only option left is to replace each LED, one at a time until the strand lights.

  • If this situation occurs, there is an open circuit somewhere in the strand which could be caused by a failed LED that has not shorted out, an improperly seated LED, or there is a bad connection (corroded LED terminals) or undetected break or short

Tips

  • Conventional light testers do not work with LEDs and because of the way they operate neither do conventional Christmas light circuit detectors
  • When purchasing LED Christmas lights, buy double the quantity and use the extra strand as replacements for failed LEDS
  • LED lights can only be inserted into their sockets one way unlike mini lights that have no polarity

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