# Why did my Christmas Angel smoke ALL 36 lamps?



## lumen aeternum (Nov 27, 2018)

I have a nice 2 dimensional painted angel which is outlined in the small incan lights, about 36. I replaced ALL the lamps last season since many were blown. I replaced some blue ones yesterday with bulbs that were darker blue glass (not just a splash of blue on the tip). She was shining last night, but today ALL the bulbs are smoked. There are about a dozen each of amber, blue, and pink/red lamps.

How should I troubleshoot this? The string is white plastic & the lamp holders are made to fit into clips on the angel, so replacing the string would be difficult. The plug does not have a removable fuse; I could destroy the plug to see what's inside (it is obviously a press fit, but not made to be taken apart). AFAIK these are the normal 2.5V bulbs.

I have one of those string tester "guns" that will pulse to trip a fusible link in a burnt out lamp, beep to find a short, etc.


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## Batou00159 (Nov 27, 2018)

Are the lamps in series excess voltage from blown lamps could cause voltage spike getting worse the more that blow ?


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## night.hoodie (Nov 27, 2018)

I'm curious about this. Could you have the wrong lamps? Or just cheaply made ones? Is there an OEM spec available for the string, or can it be discovered with testing? There are different 2.5V lamps, .3A, .5A, etc. Maybe there is a better V/A match than this years choice. Totally reaching here, of course...


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## MeMeMe (Nov 28, 2018)

lumen aeternum said:


> I have a nice 2 dimensional painted angel which is outlined in the small incan lights, about 36. I replaced ALL the lamps last season since many were blown. I replaced some blue ones yesterday with bulbs that were darker blue glass (not just a splash of blue on the tip). She was shining last night, but today ALL the bulbs are smoked. There are about a dozen each of amber, blue, and pink/red lamps.
> 
> How should I troubleshoot this? The string is white plastic & the lamp holders are made to fit into clips on the angel, so replacing the string would be difficult. The plug does not have a removable fuse; I could destroy the plug to see what's inside (it is obviously a press fit, but not made to be taken apart). AFAIK these are the normal 2.5V bulbs.
> 
> I have one of those string tester "guns" that will pulse to trip a fusible link in a burnt out lamp, beep to find a short, etc.



2.5V bulbs are for 50 lamp strings. 3.5V bulbs are for 35 lamp strings.


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## alpg88 (Nov 28, 2018)

very strange, even if you use wrong bulbs, it wont blow all, as soon as first one goes, circuit is broken, even more strange that they worked fine before, if bulbs were wrong they would blow immediately.


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## Lynx_Arc (Nov 28, 2018)

alpg88 said:


> very strange, even if you use wrong bulbs, it wont blow all, as soon as first one goes, circuit is broken, even more strange that they worked fine before, if bulbs were wrong they would blow immediately.



Some incan lamps/circuitry have parallel wires inline with each bulb that has more resistance so the current flows through the bulb but when the filament breaks and causes an open circuit then the power flows through the parallel wire. If this is the case then it is possible that every bulb could blow one at a time or several at a time. If the bulbs are too low of a voltage then every one will blow in time when they heat up excessively just like overvolting an incan bulb in a flashlight or an LED.


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## alpg88 (Nov 28, 2018)

Lynx_Arc said:


> Some incan lamps/circuitry have parallel wires inline with each bulb that has more resistance so the current flows through the bulb but when the filament breaks and causes an open circuit then the power flows through the parallel wire. If this is the case then it is possible that every bulb could blow one at a time or several at a time. If the bulbs are too low of a voltage then every one will blow in time when they heat up excessively just like overvolting an incan bulb in a flashlight or an LED.



have you ever seen such bulbs used in x-mas decorations, or even sold at stores??? i have never seen such bulb at all.


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## Lynx_Arc (Nov 28, 2018)

alpg88 said:


> have you ever seen such bulbs used in x-mas decorations, or even sold at stores??? i have never seen such bulb at all.


I've tossed all those lights years ago but I do remember lights that advertised when one goes out the rest stays on and that is how they do it. I think I've seen bulbs with a filament wire and below that anothe wire across the 2 leads. 
https://blog.christmas-light-source.com/if-i-remove-a-mini-light-bulb-will-the-others-stay-lit/


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## alpg88 (Nov 28, 2018)

i wonder how those bulbs switch between filament and bypass, cuz they can't both be open at the same time. however in this case it does not seem like such bulbs were used, if they were wrong bulbs voltage wise, they would installation right away. yet they worked just fine before.


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## alpg88 (Nov 28, 2018)

Lynx_Arc said:


> I think I've seen bulbs with a filament wire and below that anothe wire across the 2 leads.


are you sure they were not flasher bulbs? 

ok found such bulbs, http://www.wwenglish.org/en/z/xmas/christmas-lights2.htm very interesting, never seen those in stores here. possibly it is latest thing, but too late to be relevant, vast majority of lights in store today are led strings, just today i was in ace hardware, had to look hard to find none led strings.
i'd sure buy such bulbs if i there were available before, would save me plenty on new strips, but maybe that is why stores do not have them here, people would be buying a lot less light strings.


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## Lynx_Arc (Nov 28, 2018)

alpg88 said:


> i wonder how those bulbs switch between filament and bypass, cuz they can't both be open at the same time. however in this case it does not seem like such bulbs were used, if they were wrong bulbs voltage wise, they would installation right away. yet they worked just fine before.



The shunt or bypass is a higher resistance amount and current flows through the path of least resistance which would be the filament. There would be some current flowing through the bypass but it would by minimal compared to what is flowing through the filament till it breaks.


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## Lynx_Arc (Nov 28, 2018)

alpg88 said:


> are you sure they were not flasher bulbs?
> 
> ok found such bulbs, http://www.wwenglish.org/en/z/xmas/christmas-lights2.htm very interesting, never seen those in stores here. possibly it is latest thing, but too late to be relevant, vast majority of lights in store today are led strings, just today i was in ace hardware, had to look hard to find none led strings.
> i'd sure buy such bulbs if i there were available before, would save me plenty on new strips, but maybe that is why stores do not have them here, people would be buying a lot less light strings.



I've had some lights that were like this but even they can have issues that cause lights to go out the shunt or bypass can be broken or the wires going into the bulb itself can be damaged causing lack of contact. 
I've spent hours fixing strings of incan christmas lights and even had to get out straight pins and a VOM to find broken wires inside the insulation.


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## lumen aeternum (Nov 29, 2018)

MeMeMe said:


> 2.5V bulbs are for 50 lamp strings. 3.5V bulbs are for 35 lamp strings.



Well, I bought the lamps from the bucket of loose bulbs at the hardware store, or scavenged from standard strings.
So maybe I need to search for 3.5v lamps?
Can you give a reference for the voltage spec? 35 lamps is an odd size, I thought all strings were composed of independant circuits of 50.

But why would they ALL blow during the night? If the shunt failed, no power to anything. If the shunt worked, then no voltage change (I suppose a shunted lamp has the same voltage as a working lamp, otherwise it would cause voltage problems in the remaining lights).

The box is dated 2002 & says "43 super bright mini-lights." So what voltage would they likely be?


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## Lynx_Arc (Nov 29, 2018)

lumen aeternum said:


> Well, I bought the lamps from the bucket of loose bulbs at the hardware store, or scavenged from standard strings.
> So maybe I need to search for 3.5v lamps?
> Can you give a reference for the voltage spec? 35 lamps is an odd size, I thought all strings were composed of independant circuits of 50.
> 
> ...


If you are using 2.5v lights in a 43 light setup each bulb is seeing closer to 3v if the voltage is 120vac. It is possible you could have higher voltage or experienced a surge overnight of higher voltage. 2.5v bulbs pushed to 3v is a 20% overvoltage which could have possibly fried each bulb individually one at a time. The only way to know if the bulbs or wiring is individually shunted is to get a vom and put it on ohms or continuity test and check the bulbs that have blown to see if they are shorted or not or if the string is working replace a good working bulb with a burned out one and see if it works. It is possible one of the fuses burned out too in the plug itself.


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## MeMeMe (Nov 29, 2018)

alpg88 said:


> have you ever seen such bulbs used in x-mas decorations, or even sold at stores??? i have never seen such bulb at all.



Just before LED took over, this was probably the dominant bulb type. Virtually every string I have (and I have quite a few) has these bulbs in them. I thought there was more that a simple higher resistance bypass element, but could be wrong. I found that if a string was out, shaking the string would cause the failed bulb to bypass. Sometimes going along the string and flicking each bulb with your finger would engage the bypass as well (string turns on when that happens). Not unusual to bring a string out next year and find several bulbs failed, but the string lit.


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## MeMeMe (Nov 29, 2018)

lumen aeternum said:


> Well, I bought the lamps from the bucket of loose bulbs at the hardware store, or scavenged from standard strings.
> So maybe I need to search for 3.5v lamps?
> Can you give a reference for the voltage spec? 35 lamps is an odd size, I thought all strings were composed of independant circuits of 50.
> 
> ...




43 is quite the odd number. Standard strings were 50, 35, and 25, with the bulb voltage roughly 125/x where x is bulbs in the string. If you used 2.5V bulbs, it may have been brighter than you remembered .... and then they started failing one after the other.


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## lumen aeternum (Nov 29, 2018)

Suppose I splice in 7 more bulbs from another string, making an even 50 ??? Then I can use the standard 2.5V bulbs !!!
Need to figure out which wire is which though...
quick search online, I can't find colored 3.5V, only clear.


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## Lynx_Arc (Nov 29, 2018)

lumen aeternum said:


> Suppose I splice in 7 more bulbs from another string, making an even 50 ??? Then I can use the standard 2.5V bulbs !!!
> Need to figure out which wire is which though...
> quick search online, I can't find colored 3.5V, only clear.



You could calculate how much current the bulbs can handle, add up the voltage the bulbs need, subtract from 125 or so then use a resistor calculator and figure out what resistor you need and wattage you need to absorb the excess power.


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## lumen aeternum (Nov 29, 2018)

Do I need 2.5v or 3.5v for this 43 light string? Those are the only choices the OEM had, right?
Found a source of 35 light strings with 3.5v bulbs in single colors so I could buy 3 sets to get the blue, amber, red/orange that I need.


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## broadgage (Nov 30, 2018)

Here in the UK, series wired Christmas lighting bulbs are usually of the "permanent contact" whereby a failed lamp is automatically bypassed and the remaining lamps stay lit.
Common voltages are 6 volts, 40 lamps in series or 12 volts, 20 lamps in series.

Failed lamps should be replaced promptly since each failure over volts the others.


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## Lynx_Arc (Nov 30, 2018)

lumen aeternum said:


> Do I need 2.5v or 3.5v for this 43 light string? Those are the only choices the OEM had, right?
> Found a source of 35 light strings with 3.5v bulbs in single colors so I could buy 3 sets to get the blue, amber, red/orange that I need.



125/43=2.9 so 3.5 should suffice but could be a little dimmer. You could short out about 8-9 lights and it should be ok.


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## lumen aeternum (Dec 8, 2018)

Replaced all w/ 3.5v bulbs. Been shining for 24 hours, looking good.


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