Why do all the Xmas lights go out??

[Philster]

Loose, missing or broken bulbs.

Top causes which defeat the shunt feature and break the circuit clean.

100% LED here. Carry on.

[Kenm]

@Mdcastleman

It wasn’t that much trouble just to simply take a known good bulb and try replacing them one by one, since the typical string had 7 or 8 bulbs and were easy to unscrew as opposed to 50 bulbs that you often have to pry out with pliers or your fingernails.

But it was hell when two bulbs had burned out or the known “good” one wasn’t.

[Reginald_Hobbes]

@johnpost

modern lights are wired in series thought if they say that “if one goes out, the rest stay lit.” then there is a shunt in the bulb to allow electricity to flow even with a burnt out bulb. these can be poor quality products and not always work.

My FIL bought one of these.
I was skeptical, but it actually worked. Not 100% of the time, but we fixed all but one of the bad sections on our pre-lit tree.