Understanding the problem with these LED Christmas lights


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Old 10-30-21, 12:00 PM
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Understanding the problem with these LED Christmas lights

Admins, If this is the wrong forum, please move.

Trying to get some Christmas lights up. I've hooked up three lines and found some odd problems.
Now, to start these are LED lights, not regular lights. 2nd, each string has two sections which light up separately, so I can have a bulb out in a string, but only HALF the string goes out. Each string has two fuses built into the plug. Note, these are brand new lights. Never been used (though, to be honest, I purchased them 3-4 years ago. Long story, don't ask. )

Ok, now to the problem. For the sake of understanding what's going on, I'll refer to these by section: 1a, 1b, 2a etc. (the third string won't light at all, which is a whole other problem, and it is not hooked up in these pics.)
In the 1st pic below, you can see string 1 and 2 hooked up in sequence, the power source is at the far LEFT.
Strand 2, both sections are lit and working fine. The problem is with Strand 1. both sections on strand 1 are very dim when compared to strand 2. 1a seems almost off but a close up view of the bulbs shows they ARE on. (see 2nd pic) 1b is the same, though with more visibility. Neither section is as bright as 2a or 2b.

It would seem to me that If the fuses were the problem, then strand 2 wouldn't be as bright. I'm having trouble understanding where to go to look for the issues and I'm trying to save some money so please don't suggest I toss them and buy new. (Though, tossing them out is not out of the question. LOL )

 
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Old 10-30-21, 12:11 PM
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OMG, I know somewhere there is a team of engineers who diligently work their engineering knowledge to devise ways to make every know string of Xmass lights stop working after they are opened.

I refuse to troubleshoot those damn things and every year a few get pitched then new ones are purchased.

Maybe this will be the year when I can finally convince the Mrs. to forgo lights, anywhere!
 
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Old 10-30-21, 12:49 PM
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Question

As they are LED and not standard bulbs, I noticed when I was working with them that the 'bulbs' didn't go in like others. There is a definite alignment that must be followed. I'm wondering if I've put them in wrong...which may be enough to cause energy problems. But then again, strand 2 shows full power.

Head scratchin' stuff....
 
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Old 10-30-21, 02:13 PM
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Most LED strings don't have removable bulbs.
LED's put in backwards won't light.
 
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Old 10-30-21, 02:27 PM
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@PJmax: I'm glad you said 'Most' LED, as this is most assuredly LED (See pic.) I'm glad to know they can't turn on when backwards, that will save me from checking each and every bulb for alignment.
I guess I'm checking fuses next....though I fail to see how a bad fuse will still allow power through...

I'm still working on it......

 
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Old 10-31-21, 05:43 AM
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This part should not make any difference in brightness but if you unplug string 2 from string 1 does string 1 come on full brightness?

How old are these lights?

Do (did) the individual bulbs flash on and off independently of one another?

Did you change any bulbs at any time? (If you changed any bulbs and got one or two in backwards then now is the time to discard the string. Finding the bulb you put in backwards will be very tine consuming.)
 
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Old 10-31-21, 10:09 AM
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A single LED constituting a bulb is polarity sensitive. The following only applies to a volts DC powered branch. If the branch is a series circuit (one current path), a LED lamp installed with wrong polarity or a failed LED lamp will cause entire branch to be off. If the branch is a parallel circuit ( each LED lamp completes a current path) a LED lamp installed with wrong polarity or a failed LED lamp will cause only that LED lamp to be off. Any idea how the branch LED lamps are wired?
 
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Old 11-01-21, 06:11 AM
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@beelsabob
they are in sequence. If I pull one bulb, they all go off. (At least that one section. Each strand has two sections.)
Which seems to say that there may be something wrong elsewhere.....
 
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Old 11-01-21, 09:02 AM
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Based on your description, I would say each branch is a series circuit. Hence, a LED lamp installed with wrong polarity or a failed LED lamp will cause entire branch to be off. You will need a multimeter that can measure ohms to check the LED lamps for continuity checking twice by reversing the multimeter leads ( you are checking a diode). Continuity indicates lamp is good and its polarity. This polarity must be maintained when inserting the LED lamp into the socket (positive pin of LED lamp must be inserted into the socket connected to the power supply positive wire). Each section of a string is a separate circuit.
 
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Old 11-03-21, 01:49 PM
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@Beelsabob
I totally agree that they are in sequence, with two branches per string.
However, I cannot figure out why they are DIM, not off. The one string I have lit is let's say 100% brightness. This string has one branch at about 10% brightness, and the 2nd at about 50-60% brightness. i cannot figure out what could be causing this.
 
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Old 11-03-21, 04:42 PM
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My suggestion is get a multimeter that reads DC volts. Measure DC volts (fuse to common) on each string and report back.
 
 

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