How to repair Christmas Light Strings.
1) Tools And Safety
Some tools you may require to fix strings are:
Needle nose pliers, small size standard flat screwdriver, wire cutters, soldering pen and solder.
Wire nuts, electrical tape,
shrink wrap, masking tape, 9 volt battery, pencil and silicone caulking may also be needed. 120 volts AC against the skin doesn't feel good and may cause injury or death. Beware of metal objects or other paths that may be conducting from the string. Make sure the string is unplugged while working on it unless wiring is in good condition.
2) Visual Inspection
Stretch the string out so you can see it all in a line instead of coiled up. This will concentrate your attention on the wiring and bulbs. Always start at the beginning of a string and work to the end. Look for any obvious damage to the string such as melting, cuts, breaks, broken bulbs, broken or separated bulb housings, bent or missing plug prongs and burnt fuses. Tag any problems with masking tape. Label the tape with the problem if inspecting a number of strings to remind you.
3) Wiring Repair
Usually, broken or melted wiring is not a good idea to repair. In some cases, wiring can be repaired by stripping the ends of the broken wire and twisting them together. Solder the joint to keep them solidly joined. Cover the joint with a
wire nut or spread silicone caulking on the joint then wrap the joint in electrical tape. This is a temporary fix only and the string should be replaced.
4) Bulb Replacement
Most bulbs have 2 paths that electricity can take through itself. The path of least resistance is through the
filament of the bulb causing it to light up. If the
filament is burnt or broken, then that path is lost and the electricity will have to travel through the shunt keeping the rest of the string lit. If the
filament and the shunt are burnt then the bulb forms a break in the string. If a bulb in a string is out and the other bulbs are lit, then pull that one out and replace with another of the same type and color. If the bulb is tight in the bulb housing, gently use wire cutters to separate the bulb holder from the bulb housing. Careful not to squeeze cutters too hard but enough to separate the bulb. Pull the bulb out with fingers. If replacement bulbs are from another string or type of bulb housing style, gently bend the small wires at the base of the original bulb holder out straight. Pull the bulb out of the bulb holder. Beware that bulbs are made of glass and may cut you. Take the bulb out of the donor bulb holder and straighten the wires. Insert the bulb into the original bulb holder and bend the wires against the base of the bulb holder.
5) Fuse Replacement
If the fuses are missing, replace them with the correct type of fuse for that string. If a fuse is burnt out, remove the fuse. If fuse is stuck, gently pry it out with screwdriver or pointed tool. If fuse compartment is melted then the plug may have to be replaced or string discarded. Inspect the inside of the fuse compartment for debris or corroded fuse contacts. If corrosion is not bad, then gently scratching the surface of the contact will clean off the corrosion.
6) Plug Replacement
If a plug is ruined from bent, broken or missing prongs, broken wires, melting of the plug or fuse compartment, then the string may have to be discarded. In some cases, a replacement plug can be installed with a vampire type plug or similar. Cut the wire off close to the damaged plug. Some plugs require stripping of the wire so check the instructions for that new plug.
7) Bulb Housing Repair
Typically, melted, broken or missing bulb housing shouldn't be repaired. Usually bulb housings cannot be replaced but if most of the housing is still intact, it can be insulated to keep it safe from more damage. Spread silicone caulking around the housing and let dry. Housings can be cut out and the wires stripped. Join the wires by twisting them together and soldering them. Cover the joint with a
wire nut or spread silicone caulking on the joint then wrap the joint in electrical tape. This is a temporary fix only and the string should be replaced.
8) Flasher Bulb Replacement
Some strings have flasher bulbs at the start of the string. If the flasher is burnt out, then remove the bulb and replace with the same type of bulb. If you don't want the string to flash any more, then pull the flasher out and replace with the same type of bulb as the rest of the string.
9) Light String Diagnostics
Start with the visual inspection with the string unplugged. If there are no obvious signs of damage, then plug the string in. Make sure the source of power you plug the string into is also working by plugging a good string into it. Plug the string into the outlet. If no lights are lit, unplug and check the fuses first. If fuses are good, then one or more bulbs are bad. If some of the lights are on then the problem lies in the section that is dark. Gently shake the string to see if there is intermittent contact. Sometimes shaking sections of the string will isolate the problem. Start at the plug end and pull out the bulb. Check for damage to wires and bulb holder. If no obvious signs of damage, then check if bulb lights by touching to the contacts of the 9 volt battery. If bulb lights, then replace bulb back into string, being careful not to disturb wires against the base of the bulb holder. If bulb doesn't light, replace bulb with same type of bulb in the same type of holder (see #4 above). Continue down the length of the string until all bulbs are checked. In the event that all bulbs are checked and the string still won't light up, check the string again. If the string still refuses to light up, then there may be a break in the wire inside the wiring insulation. In that case, discarding the string is best.
10) Bad Strings
We recommend to discard strings that just won't work. Incandescent
mini lights and other strings are getting cheaper all the time with the move toward LED lighting. Easier and cheaper to replace the string other than chancing a fire.
Hopefully, this has given you some insight to that string that is causing you problems.
This is what I bought for $25 bucks! What a deal! (sort of)
After sorting through approximately 55 strings of various types and stowing each string in a separate bag, we ended up with this (minus the blowmolds). Upon prelimanary examination of the strings, we found that about 15 or more strings had no plugs on them. So repairs or discarding them will be on a case by case basis.
