Christmas tree lights! grumble grumble

[NutmegCT]

The sad remnant of my brain is losing patience with the tree lights. All five strings worked fine last year - of course this year, four of five strings are dead in the water.

LED bulbs, 125v AC, fuses and fuse holders test fine. End of the string has 125v, so current is making it through the system. But not one bulb is lit.

It's a "three wire" system, which should allow working bulbs to light, even if a few are dead. Each string plugged into power outlet alone is dead too.

Seems weird that one string works fine, but the other four strings all have the same dead bulb situation!

Tom M.

 

[Gliderman8]

……..End of the string has 125v, so current is making it through the system. But not one bulb is lit…….

125AC seems like a lot of voltage to power an LED. Is there a built in transformer?

 

[NutmegCT]

Thanks Elliot. The plugs show "max 125v"; voltage at my outlets is 115-120.

TM

 

[bobhustead]

Have you put each string directly into the wall outlet? The one-out-doesn't-matter feature has never blown my dress up.
Bob

 

[NutmegCT]

Each string plugged into power outlet alone is dead too.

Yep - tried that too. The four strings that don't light, still don't light when plugged in one at a time to the outlet.

weird

 

[bobhustead]

Sorry, I didn't completely read your first post. Sounds like you can economically fix this by going to WalMart.
Bob

 

[NutmegCT]

Definitely one way to go.

But I'm trying to figure out what actually caused this. Four of five strings gone out, even tho' all the LEDs work individually when testing bulb resistance using a multimeter.

 

[bobhustead]

Danged quantum physics.
Bob

 

[NutmegCT]

Actually, a small LED will light when testing resistance, as the mm send a tiny bit of current through the mm leads.

What's mystifying, is that current is going from the wall outlet all the way to the end of the three-strand string - but none of the bulbs are lighting.

yeesh

 

[bobhustead]

Since you are still messing... What happens if you put the working string in second position after the outlet? Hope I didn't miss that you tried that too.
Bob

 

[Gliderman8]

Thanks Elliot. The plugs show "max 125v"; voltage at my outlets is 115-120.

TM

I would have guessed that the voltage would be reduced or even changed to DC.

 

[NutmegCT]

Bob - No difference in putting a working string second. The dead string plugged into the wall outlet - still dead. Plug in the good string to the end of the dead string, the good string lights up fine.

Elliot - the voltage at the end of the dead (or working) strings is still 115v AC.

 

[Gliderman8]

 

[Pat MM]

I know why.


Gremlins!

 

[NutmegCT]

 

[Gliderman8]

I bet if you dissect one of those strings you’ll find a bad resistor or diode. Those components could be inside the plug.
The way you fix the problem is to take Bob’s advice in post #6.

 

[NutmegCT]

Walmart? I shall not yet admit to defeat!

December, 1941.

 

[JPSmit]

The sad remnant of my brain is losing patience with the tree lights. All five strings worked fine last year - of course this year, four of five strings are dead in the water.

LED bulbs, 125v AC, fuses and fuse holders test fine. End of the string has 125v, so current is making it through the system. But not one bulb is lit.

It's a "three wire" system, which should allow working bulbs to light, even if a few are dead. Each string plugged into power outlet alone is dead too.

Seems weird that one string works fine, but the other four strings all have the same dead bulb situation!

Tom M.

You buy Lucas - you get Lucas

 

[Basil]

The sad remnant of my brain is losing patience with the tree lights. All five strings worked fine last year - of course this year, four of five strings are dead in the water.

Well of course silly, you're not supposed to put them in water!