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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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How to choose an appropriate LED
I have one of those costly animated outdoor Christmas displays with
white LED lights on it. A few of the LEDs are dead. There is no manufacturer info available. I know LEDs all have a different current draw. I am not sure how critical it is, to choose a replacement bulb. Does it matter, or will any white LED work, as long as it fits the socket? These are sort of the domed type, but have flat tops. Nothing fancy, and they dont have to look identical since they are inside of a coating. My thought is to just buy a string of white xmas lights after the holiday (on sale) and use them for replacement bulbs. But maybe I need to know more about the current draw or something. I ve never had to replace LED bulbs before. I replaced amny of the old xmas light strings that has incandescent bulbs, and with them, you had to match the number of bulbs to get the correct voltage. |
#3
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How to choose an appropriate LED
On Monday, December 25, 2017 at 12:35:44 PM UTC-8, wrote:
I have one of those costly animated outdoor Christmas displays with white LED lights on it. A few of the LEDs are dead. There is no manufacturer info available. I know LEDs all have a different current draw. I am not sure how critical it is, to choose a replacement bulb. Does it matter, or will any white LED work, as long as it fits the socket? There's multiple shades of 'white' available; if you can't see the replacements side-by-side, they won't be exact. Generally available (new stock) LEDs in the same package are likely (for heatsinking reasons) to be electrically compatible. And, cheaper than a set, you can get bags of LEDs from a variety of suppliers, like this: https://www.ebay.com/itm/3mm-white-LED-light-100pcs-Light-Emitting-Diode/182490012569?epid=571206918 but polarity, case size, color, are just as mysterious as the 'no manufacturer info available' item you are thinking to rebuild. |
#4
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How to choose an appropriate LED
On Mon, 25 Dec 2017 14:18:44 -0800, Jeff Liebermann
wrote: On Mon, 25 Dec 2017 14:34:36 -0600, wrote: I have one of those costly animated outdoor Christmas displays with white LED lights on it. A few of the LEDs are dead. There is no manufacturer info available. I know LEDs all have a different current draw. I am not sure how critical it is, to choose a replacement bulb. Does it matter, or will any white LED work, as long as it fits the socket? These are sort of the domed type, but have flat tops. Nothing fancy, and they dont have to look identical since they are inside of a coating. My thought is to just buy a string of white xmas lights after the holiday (on sale) and use them for replacement bulbs. But maybe I need to know more about the current draw or something. I ve never had to replace LED bulbs before. I replaced amny of the old xmas light strings that has incandescent bulbs, and with them, you had to match the number of bulbs to get the correct voltage. Two days after I hung my string of Hanukah lights, the local squirrels gave it a taste test resulting in about half the string going dark. You might inspect your lights for similar damage. If so, splice or solder the wires back together and it should work. Be sure to use shrink tube or liquid electrical tape for insulation. My 25ft string has about 6 breaks from similar squirrel damage from previous years. If you plan to fix it, take the time to determine how it's wired. Some possible schematics and wiring diagrams: https://www.google.com/search?q=led+christmas+light+wiring&tbm=isch Trace out your wiring and see what matches. Try to fix just one section that's currently not lit. If you find it, don't fix it immediately. Use a VOM or DVM to measure the current and you have your answer. Some LED's have built in resistors or current regulators like this: https://www.google.com/patents/US8007129 You can determine which LED is blown in one segment, attach needles to the VOM or DVM leads and probe across each LED by puncturing its wires. If you see an unusually large voltage, the LED that you're straddling is the culprit. Be careful as most light strings do not have any isolation from the AC power line. Use a 117-117VAC isolation transformer or be VERY careful when probing live power. Thanks for the help. This is an outdoor display, but I use it indoors. So no animals have chewed on the wires. I dont hasve whole sections out, just two or three bulbs that dont light. I could just leave it alone, but if it's series wired, I know it will eventually overload other bulbs. (Yea, I need to get a better look at the way it's wired). Plus this was a very costly and very pretty display, so I want to keep it in tip-top shape. (Which is why I only use it indoors). The reason I got this, was because it was a store display, and I got it at a much reduced price. So, running it in the store for weeks probably killed the weak LEDs. However there was no box or instructions. I'm sure it was NOT made in the US, so finding the manufacturer is not gonna help determine the proper bulbs. |
#5
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How to choose an appropriate LED
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#6
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How to choose an appropriate LED
On Tuesday, 26 December 2017 11:09:33 UTC, wrote:
On Mon, 25 Dec 2017 14:18:44 -0800, Jeff Liebermann wrote: On Mon, 25 Dec 2017 14:34:36 -0600, wrote: I have one of those costly animated outdoor Christmas displays with white LED lights on it. A few of the LEDs are dead. There is no manufacturer info available. I know LEDs all have a different current draw. I am not sure how critical it is, to choose a replacement bulb. Does it matter, or will any white LED work, as long as it fits the socket? These are sort of the domed type, but have flat tops. Nothing fancy, and they dont have to look identical since they are inside of a coating. My thought is to just buy a string of white xmas lights after the holiday (on sale) and use them for replacement bulbs. But maybe I need to know more about the current draw or something. I ve never had to replace LED bulbs before. I replaced amny of the old xmas light strings that has incandescent bulbs, and with them, you had to match the number of bulbs to get the correct voltage. Two days after I hung my string of Hanukah lights, the local squirrels gave it a taste test resulting in about half the string going dark. You might inspect your lights for similar damage. If so, splice or solder the wires back together and it should work. Be sure to use shrink tube or liquid electrical tape for insulation. My 25ft string has about 6 breaks from similar squirrel damage from previous years. If you plan to fix it, take the time to determine how it's wired. Some possible schematics and wiring diagrams: https://www.google.com/search?q=led+christmas+light+wiring&tbm=isch Trace out your wiring and see what matches. Try to fix just one section that's currently not lit. If you find it, don't fix it immediately. Use a VOM or DVM to measure the current and you have your answer. Some LED's have built in resistors or current regulators like this: https://www.google.com/patents/US8007129 You can determine which LED is blown in one segment, attach needles to the VOM or DVM leads and probe across each LED by puncturing its wires. If you see an unusually large voltage, the LED that you're straddling is the culprit. Be careful as most light strings do not have any isolation from the AC power line. Use a 117-117VAC isolation transformer or be VERY careful when probing live power. Thanks for the help. This is an outdoor display, but I use it indoors. So no animals have chewed on the wires. I dont hasve whole sections out, just two or three bulbs that dont light. I could just leave it alone, but if it's series wired, I know it will eventually overload other bulbs. (Yea, I need to get a better look at the way it's wired). Plus this was a very costly and very pretty display, so I want to keep it in tip-top shape. (Which is why I only use it indoors). The reason I got this, was because it was a store display, and I got it at a much reduced price. So, running it in the store for weeks probably killed the weak LEDs. However there was no box or instructions. I'm sure it was NOT made in the US, so finding the manufacturer is not gonna help determine the proper bulbs. If they're 5mm LEDs, a bag of mixed random 5mm chinese LEDs would work. Who knows if they'll match on brightness & colour though. NT |
#7
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How to choose an appropriate LED
On Tue, 26 Dec 2017 05:08:41 -0600, wrote:
Thanks for the help. This is an outdoor display, but I use it indoors. To the best of my limited knowledge, indoor and outdoor Hannukah lights are the same. Incidentally, look for the UL 588 label: https://industries.ul.com/wire-and-cable/seasonal-lighting So no animals have chewed on the wires. Assumption, the mother of all screwups. Just inspect the wiring and see if there's any damage. You got used which means it could have been abused in a multitude of ways. I dont hasve whole sections out, just two or three bulbs that dont light. It could be a parallel wired affair with built in current limiting resistors as mentioned in the patent: https://www.google.com/patents/US8007129 I could just leave it alone, but if it's series wired, I know it will eventually overload other bulbs. Look at the way series arrays are wired. There's no way to overload them, unless you're into shorting out the LED's that died. (Yea, I need to get a better look at the way it's wired). You need to get a better look at the way it's wired. You need to get a better look at the way it's wired. You need to get a better look at the way it's wired. You need to get a better look at the way it's wired. I thought it would help if I repeated that a few extra times. Plus this was a very costly and very pretty display, so I want to keep it in tip-top shape. (Which is why I only use it indoors). Costly or overpriced? The reason I got this, was because it was a store display, and I got it at a much reduced price. Yes, but you're suppose to do that AFTER the holidays, when the stores unload all their holiday paraphernalia. Are you sure you got a good price, or did the store just unload something broken which they couldn't sell? So, running it in the store for weeks probably killed the weak LEDs. Unless overheated or run a unusually high current, LED's should last thousands of hours. You're thinking of the bad old days of incandescent lights, where replacing bulbs was a regular exercise. Before you replace any LED's, You need to get a better look at the way it's wired and determine if there's an internal ohmsistor or current limiter. Replacing one of those with an ordinary LED is going to produce a very bright flash before the fuse blows. However there was no box or instructions. If anything were included in the box, it would be a wholesale repudiation of responsibility and various legal disclaimers in a dozen foreign languages. I originally suspected that if I did the research, I would find that there are a few giant factories in China making both the quality and the junk lights, which are then packaged, private labeled, distributed, and sold by a multitude of disreputable vendors. Well, more than a multitude. This list shows 863 manufacturers: http://www.made-in-china.com/products-search/hot-china-products/Tree_Light.html and 535,000 vendors in China: https://www.alibaba.com/countrysearch/CN/christmas-light.html Identifying your lights may be difficult. I'm sure it was NOT made in the US, so finding the manufacturer is not gonna help determine the proper bulbs. There are no Hanukah light manufacturers left in the USA. https://www.christmasdesigners.com/blog/made-in-usa-christmas-lights/ -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#8
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How to choose an appropriate LED
On Tuesday, 26 December 2017 17:04:57 UTC, Jeff Liebermann wrote:
On Tue, 26 Dec 2017 05:08:41 -0600, wrote: 8 So, running it in the store for weeks probably killed the weak LEDs. unlikely Before you replace any LED's, You need to get a better look at the way it's wired and determine if there's an internal ohmsistor or current limiter. Replacing one of those with an ordinary LED is going to produce a very bright flash before the fuse blows. Quicker to just replace & see if they work. If the new LEDs light and the old don't, then different limited LEDs needed. NT |
#9
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How to choose an appropriate LED
On Tue, 26 Dec 2017 09:46:43 -0800 (PST), wrote:
Quicker to just replace & see if they work. If the new LEDs light and the old don't, then different limited LEDs needed. NT I was wondering what the white stuff that falls out of the sky around this time of year might be. Initially, I thought it might be snow, but after considering your suggestion, I suspect it might be the fallout from exploding white LED's that were tested using your methodology. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
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How to choose an appropriate LED
On Tuesday, 26 December 2017 19:01:41 UTC, Jeff Liebermann wrote:
On Tue, 26 Dec 2017 09:46:43 -0800 (PST), tabbypurr wrote: Quicker to just replace & see if they work. If the new LEDs light and the old don't, then different limited LEDs needed. NT I was wondering what the white stuff that falls out of the sky around this time of year might be. Initially, I thought it might be snow, but after considering your suggestion, I suspect it might be the fallout from exploding white LED's that were tested using your methodology. Lol. I doubt it. The OP hasn't a clue what he's got, the possibility of killing a 1 cent LED by overcurrent is no big deal. NT |
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