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LED strings going out


ItsMeBobO

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Zip tied sets of Red Green Blue LEDs together then wrapped mini trees. Dang it now the Blue only is out on two of them. Looks bad in the display :P

The little in plug fuses were grey so I replaced them. As soon as I plugged it in I heard the new fuse pop again.
Spent time looking all over but was unable to find any cuts or shorts in the wire with it being wrapped all up with other strings.

Why would the fuses blow? Any hints on how to recover this string without striping it?

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Bob,

My answer would be to put a new blue string on and fix it after the season, unless you have time to spend. I think the only way you're going to find the problem is to strip it apart. The only other option I see is if it is neatly wrapped, you might be able to follow the string with a lightkeeper pro...

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ItsMeBobO wrote:

Zip tied sets of Red Green Blue LEDs together then wrapped mini trees. Dang it now the Blue only is out on two of them. Looks bad in the display :P

The little in plug fuses were grey so I replaced them. As soon as I plugged it in I heard the new fuse pop again.
Spent time looking all over but was unable to find any cuts or shorts in the wire with it being wrapped all up with other strings.

Why would the fuses blow? Any hints on how to recover this string without striping it?


What are the string mounted on?

Wire Frames?
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tomskillman wrote:

Bob,

   you might be able to follow the string with a lightkeeper pro...



Thats a good suggestion except I'm pretty sure the Light Keeper Pro won't work on Led's. Only on Incandescents. Someone please correct me if I'm wrong.
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Sadly I failed to get spares two years ago when I bought these. Will look around for new ones.
What I am looking for is reasons why the fuse blows? Makes me think they all soon follow as no cuts were found and they worked befor the rain. They are dry now but could water get inside something to short it?

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I don't have an answer for you. What I am going to say will also not be encourging for you.

A couple years ago I had 12 (whole case) of Blue LEDs fail. These were 'replacement' LED strings. They did not blow the fuse though. They just got dimmer and dimmer. The lasted about 3 weeks.:X

I hope no more LED strings quit working.

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Dan C wrote:

tomskillman wrote:
Bob,

you might be able to follow the string with a lightkeeper pro...



Thats a good suggestion except I'm pretty sure the Light Keeper Pro won't work on Led's. Only on Incandescents. Someone please correct me if I'm wrong.

You are correct, do not use the LightKeeper Pro on LED's.

Blown fuses need to be analyzed using a Ohmeter instead of a tester.
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Will also add that blown fuses are not a single, or few LED failure. It is more likely an insulation flaw somewhere. Treat that string as dangerous.

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I wouldn't do this quite yet if I was you, but when you are sure they are bad you could put something like aluminum foil in instead of a fuse. Most likely wouldn't work but you could give it a try.

This could also be very dangerous and I wouldn't do this with that string still attached to anything. (I know everyone here is going to say that it isn't safe and all but its a last resort)

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With LED the odds that this is something that you can escape from that action without damage is far less than incandescent.

What are the odds that the 10w string of led is really drawing just a little more than the 360w that the fuses should be blowing at? And if so, where is this extra 350+ watts being dissipated in a way That is not a fire hazard?

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I suspect that the rectifier on the strings in question has failed (that's the little bulb in the string near the plug). I have had several of them fail over the years. This is especially true if the strings are full wave rectified.

If you have several extra strings that have other problems, you might be able to wire the plugs and rectifiers in to bad strings to check them.

-Gary-

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Gary Levelius wrote:

I suspect that the rectifier on the strings in question has failed (that's the little bulb in the string near the plug). I have had several of them fail over the years. This is especially true if the strings are full wave rectified.

If you have several extra strings that have other problems, you might be able to wire the plugs and rectifiers in to bad strings to check them.

-Gary-



I have had the same experience, but this did not blow fuses in my case.

Did your strings that failed blow the fuses?
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Hi Bob,

Several thoughts. Did you get these strings from Travis? I had some whites and a string of multi that failed from that source. The white string the bridge diode did fail. On the multi it turns out to be harder to find. But it did fail when it rained. In the case of the multi there was the diode wart and then two Resistor warts one at each end. On this string after I replaced the full wave bridge thinking it was diodes again. I did a test burn inside. No more fuses popping, but after about 15 minutes I noted that one of the resistor warts was very hot and the plastic was very melted. I assume that some water got into the wart and shorted it out. Might of fact if I remember correctly. After finding this melted wart. I did a diode check on the wave and it was all good, all 4 of them.

Summary: bad full wave bridge or bad resistor wart and water has gotten in and shorted it out.

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LED's like incandescent can go into a cascade failure. That means enough lights failed to over drive the remaining lights an destroy them also until the rating of the fuse is reached.

The blob may or may not have diodes, it depends if the string is Full or Half wave. The blob will most likely have a bias resistor also.

If the LED string is full wave then the blobs have 2 diodes inside and also possibly a bias resistor. If a diode shorts out or opens up, what will happen is that section of lights will go back to Half Wave function and not blow a fuse.

I know this from experience, the blown fuses is indicating a serious failure, if you are not experienced in troubleshooting do not go there. Do not add foil around fuses, that may cause a fire or take out the triac on your controller.

Just add another string of lights to get you though the season and troubleshoot it next month.

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Is it possible that water is getting in the female plug and shorting?

I have heard of people sealing the female end with hot glue -- might be worth a try...

Jerry

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Out of all my lights, approx 50,000 I have had the most failure with the blues. I have talked to Paul at CDI about this and he has no clue. I run a four color show but an really starting to think about leaving the blues out. I think I had at least 6 strings of blue lights go bad this year, compared to one string of white. Add to that about 3 strings last year, it is starting to sorry me. LED is the way to go, but I am getting the blues. What I have spent in lights is probally what I would have spent in service upgrade (my 50,000 lights = 16 amps) and the colors are so much more intense.

Merry Christmas all

Denise Brunner

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-klb- wrote:

Will also add that blown fuses are not a single, or few LED failure. It is more likely an insulation flaw somewhere. Treat that string as dangerous.


ditto:
blown fuses are caused by shorts/too much current. You may have to check every inch of cable.
Somewhere in there is a diode/set of diodes and maybe a small circuit board with some caps on it(for either half wave or full wave). On mine, these were on each end of the plug and the socket.Water may have gotten in and shorted something out.
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