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One of my sets of Christmas lights is not lighting up at all. It has sealed non-removeable bulbs. The wiring is still fine because the socket end has power when the plug end is plugged in. There are no fuses to replace anyways.

Is there any way to find, and repair or replace, the burnt out bulb(s)?

I figure the answer is no, it's not possible, because the bulbs are sealed non-removeable, but looking for a second opinion before I dispose of them. As the photo shows, the light set is in like-new condition, no damage to wires or bulbs or plugs.

I watched a bunch of videos (YouTube search) about repairing lights and replacing fuses and bulbs. But none of those tips apply because mine are sealed non-removeable bulbs with no fuse. According to another source that makes them, they are commercial grade, higher quality and longer lasting. Until they aren't.

Close up photo details of plugs and bulbs to show that:

  • Plugs do not have fuses, no tab slider to reveal fuse pocket
  • Bulbs are sealed non-replaceable, they can't be pulled loose

enter image description here enter image description here

Ting Shen Christmas lights

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    1. there's a fuse in the plug, there has to be in the US. 2. Are you sure you can't remove the "bulb", even with unreasonable force? 3. there's a by-pass 3rd wire that would frustrate checking for correct operation by means of operational down-chaining.
    – dandavis
    Apr 15, 2023 at 19:09
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    Are this LEDs inside or bulbs? You should be able to pull up the bulb. Try it! It is smarter to buy LED-stripes with 3 Volt, all LEDs in parallel, then only the defect LED will not lit up, the rest will work and you can find the defect LED very fast.
    – MikroPower
    Apr 15, 2023 at 19:14
  • @dandavis note that "socket end has power when the plug end is plugged in" thus it can't be fuse, if fuse is blown then there is no power at plug. I'm in Canada not US. Bulb housing is sealed, refer to Christmas Designers link, commercial grade sealed bulbs is a thing
    – JohnC
    Apr 18, 2023 at 1:27
  • @MikroPower Incandescent bulbs. Bulb housing is sealed
    – JohnC
    Apr 18, 2023 at 1:28
  • Press the bulb against a very bright flashlight and look at the bottom part of the bulb. Often times, you'll be able to see the telltale burn marks on a burned-out bulb.
    – bta
    Apr 18, 2023 at 18:05

2 Answers 2

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"Possible" is a funny word.

I was able to get one of these strings working when it failed Christmas night. It was the string going around my doorway so really important. With the string plugged in to a GFCI outlet, I got an insulated coax staple and stuck it into the insulation of both wires going into a socket. If the bulb was good, nothing happened but if the bulb was the bad one, open circuit, shorting out the wires would light up the string. After going through half the string, I hit the bad bulb. Then I cut off the bad bulb and spliced the two wires together.

Removing a bulb from a series string of lights probably increased the voltage per bulb from 4.8 volts to 5 volts. Doing this too many times would raise the voltage enough to burn out the remaining bulbs pretty fast.

I would not have done this if it wasn't Christmas night with all the stores closed

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  • TBH, it's not that often that intentionally shorting a circuit is used for troubleshooting & repair, but hey, whatever works in a crunch!
    – FreeMan
    Dec 21, 2023 at 13:53
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    @FreeMan You're so right and I'd never suggest it for a parallel circuit but with the series, it's only about 2.5 volts, much less than sticking a 9 volt battery on your tongue... or talking your little brother into doing it
    – JACK
    Dec 21, 2023 at 14:42
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They look very much like a variation on a theme of standard encapsulated pull-out bulb

enter image description here

The first or last may be a fuse bulb, the rest will all be the same type. Any one blows, they all go out. As for the price of three of these as replacements would be about half the price of a new set of LEDs [which are wired in parallel so losing one means you only lose one] then I'd not be in too much of a rush to repair it.

Further googling says it might be a C3, as opposed to the M5 above. This page has a lot of pictures but not much other info - https://www.decoratingspecial.com/difference-between-c5-c7-c9-christmas-lights/ - I can't find bulbs by those designations in the UK, but that's often the case for bulbs, UK/US. We use totally different common sizes.

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  • Not sure about that...if you look closely, it looks like the base of the bulb is actually molded to the bulb holder, so not removeable.
    – Huesmann
    Apr 16, 2023 at 12:32
  • There's another variation on that design where the glass envelope itelf just pulls out, rather than having the separate collar. tbh, for a set of 5 quid/buck xmas lights, I wouldn't really bother getting too deep into it. We probably bin one string & buy a new one every year, as whim [& my girlfriend] dictates ;)) I think the last set of series-connected incandescents went to the great recycler in the sky many years ago.
    – Tetsujin
    Apr 16, 2023 at 12:59

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