Tearing down a failed LED bulb

todd-harrison-led-bulb

[Todd Harrison] was thinking of replacing some incandescent light bulbs in his house with LED models, so and his wife picked up a single candelabra bulb to test before they spent the cash to swap them all out. The bulb died in about a week’s time, so [Todd] got out his trusty electronic disassembly device (his hammer), sharing his post-mortem examination with us.

After taking a cursory look at it, [Todd] found that the circuit powering the bulb was not overly complicated. A small bridge rectifier along with a few caps and resistors are all that was used to power the device, making it’s failure a bit puzzling. When [Todd] wired it up to his power supply, the bulb lit up, much to his surprise. His best guess as to why it died is that the shrink wrap around the PCB managed to cause a short, though he also noticed that one of the bridge rectifier’s legs was not soldered down.

He started tooling with the light to find out more about it, but he managed to blow out a handful of LEDs in the process. All in all the LED lighting swap was a disappointment, but at least he had some fun along the way!

Continue reading if you’re interested in seeing [Todd’s] diagnosis in its entirety.

Comments

  1. jon says:

    This is the single biggest problem with LED light bulbs. In order to keep the cost down, they skimp on quality, and when they skimp on quality, the bulb never lasts it’s 10,000-50,000 hours.
    I’ve had half dozen of the bulbs like in the video go bad on me in a matter of weeks instead of years, eventually I just went with cold cathode bulbs instead, draws more power, but at least they turn on every time, instead of burning out after a week, or worse turning on 50% of the time.

    • Eventhorizon says:

      Do you even consider calling that a “quality”? More like a racket of some sort.

      • Dax says:

        Worse than that, the LED chip manufacturer’s stated luminous output per watt, lifetime and color temperature are only valid at a nominal junction temperature of 25*C (note: not ambient temperature) and typically for currents less than 1/3 the nominal.

        All those are thrown right out of the window when the LED chip is actually put into a lamp, put in the fixture and run at a higher brightness. For example, the Tj shoots up to a hundred degrees or more in seconds after you turn it on.

        Trying to find out what the real preactical values are is made intentionally difficult by the manufacturer of the chip so all the values, brightenss, efficiency, lifetime are usually highly exaggerated as the bulb manufacturer quotes the provided values straight out of the data sheet.

      • Eventhorizon says:

        Well said. It’s literally not “Powering” the LED when in use, it’s rather burning it. For an LED not to last at least a year has some pretty serious defects. I think it’s not even designed to light up, and it’s just the LED’s durability to over voltage/current that’s keeping it alive for a week’s time.

  2. fartface says:

    It works great if you dont buy the china junk like he is using. I spent $39.00 each on GE bulbs and they work great PLUS have a real warranty for 10 years.

    If you are cheap and buy the cheap junk, dont expect it to last 10 years.

    • ScottInNH says:

      For once I agree with @fartface.

      This is the SAME problem as with CFL’s… consumers dip their toe in the water with the lowest price device, which promptly fails, and the consumer discovers the warranty was worthless.
      Then people blame the technology -and- the “elite” science-based sources of news.

      If you’re going to buy a cheap LED bulb, go with the store/house brand at Lowes and Home Depot (Utilitech or Ecosmart). Check the warranty – you can return failed parts to the STORE (not required to mail the whole thing back at higher cost than the bulb was).

      The other thing to note about LED bulbs – they don’t like to heat up. If you run them inside sealed tulip-shaped (open on one side only) enclosures expect them to burn out early. For the last year I have 3 Utilitechs in a ceiling light fixture, tulip shaped glass globe, and 1 burned out but was replaced for free.

      I wish these things were configurable. I find the heat sinks on most bulbs to be too small and may shorten their life.

    • >I spent $39.00 each on GE bulbs and they work great PLUS have a real warranty for 10 years.

      And if you have any luck at all, the “ink” on your receipt will last about 3 years.

      Quick, where is your LED light bulb receipt? Will you even be able to find the dang thing next year?

      And what exactly do you have to do to get the warranty honored? Ship it to GE, wait 6-8 weeks, and hope they haven’t lost the paperwork?

      LEDs are just tipping the point where they make sense in retrofitting, but I can’t believe a dang thing they say on their packaging.

      If they really wanted to offer a 10 year warranty, they could laser-etch a barcode on each bulb to be scanned on the day of purchase (just like gift-cards are swiped on the day of purchase) Then they could make long term agreements with places like wal-mart to provide warranty service. Walk in, swap bulbs, walk out.

      I would love it if the industry adopted subjective tests for light output that let us compare apples to apples too.

      • eldorel says:

        Not sure about the rest of it, but I photocopy all of my receipts after purchase, and staple the original to the copy.

        In 5 years, thermal paper is useless, but a copy + faded original has been enough to force warranty returns in the past.

  3. willaim says:

    i think you will notice a similar though not quite so pronounced in the CFL technologies too what good is a lightbulb that saves some money over the course of its expected life when they burn out in 1/4 of the time than incandescent they are trying to replace while costing 10 to 100 times more and in the case of CFLs come with dangerous mecury. Just love those savings! You may say that led bulbs fix some of the short comings of the cfl but at the cost of more material and more dangerous materials the dispose of at the end of their lifetime where as with the trusty incadescent it is mostly sand and metal its far easier to recycle too.. I think after the pros and cons are weighed none are a perfect technology so the best course of action imo is non polluting renewable power generation… And then maybe they can stop trying to take away our inefficent durable incandescents.

  4. oodain says:

    i use some mid range led bulbs everywhere but the bathroom and basement,

    7 bulbs all in all, i bhought a pack of 10 and i have had a single failure,
    after i switched that one i havent had any issues.

    i had to remove my old bulb dimmers before installing them though.

  5. Chambon says:

    10 Year warranty? Yeah, sure wait until you want to collect on that… Where is your receipt (doubt you will keep it for more than a year)? You also will have to pay shipping (which will cost you at least 1/2 of the cost of the bulb). Warranties on products like that are not worth the paper they are printed on. Just buy the cheap chinese junk and change it when it fails (you will still come ahead price-wise).

  6. yamaplos says:

    I love this things! I am saving the little glass cover thing to us for some project down the line. Meanwhile I am re/purposing the LEDs everywhere, keeping the assembly for 120v, like underneath my microwave oven, and I have a bunch of nice white LEDs to play with.

    BTW, the GE warranty (may be) good if 1) you keep the receipt 2) pay for shipping the thing back to GE land. GE quality might have been something – in the 1950s. Nowadays they’re Chinese too. 2 of 4 GE halogens lasted a bit over a month. The 4 GE CFLs I put in the bathroom at the same time from the same box have all different colors, and one of them buzzes. I prob should stop sourcing my lightbulbs at Sam’s Club, but hey, as they say, they’re cheap!

    • yamaplos says:

      oh gee whiz, I should check my spelling’s :-) before hitting [submit]
      /these/ things, to /use/, for /re-purposing/

      sorry

      (BTW, regarding the distinction between /it’s/ and /its/ in postings and comments, looks like grammar was of similar quality as the assembly of these things we complain of – have we been outsourcing education also? or what is the going excuse?)

  7. dl7und says:

    Sorry, but that is just a piece of cheap junk MIC, not a real bulb. Everyone who knows which end of the solder iron gets uncomfortably warm could easily manufacture something on at least the same level on the kitchen table. A real LED bulb looks slightly different from both outside and inside…

  8. rue_mohr says:

    leds are current devices, so the design point is the 10mA. The electrolytic is the DC filter and the other big cap will be in series with the AC supply to provide the impedence for limiting current. The 470 ohm resistor prolly helps take up the difference over the 90 to 130V input voltage range. the 81V wouldn’t be hard to generate with a switching power supply.

    hey Robotgrrl, you havn’t joined up with me yet on irc regarding your switching power supply design!

  9. steve says:

    Nice post, thanks. To many people in the hacker community the guts of 110V or 230V LED bulbs have rather been shrouded in mystery so far.

  10. smoketester says:

    Enjoyed seeing the whole troubleshooting process from start to finish. Especially liked how the test equipment was used along with the math being broken down. Makes me understand the need for a good DC power supply that is bridgeable to get the 60 volts even though most of the time I’m working at TTL levels.
    And above all, I enjoy the “What just happened moment” shortly followed by some good ol’ SMOKETESTING :)

  11. tantris says:

    a few observations:

    we’re still in the beginning phase for led bulbs, you will pay the early adopters’ fee.

    good leds exist, but most stuff out there is either junk or over hyped in wattage equivalence

    as a rough rule, the more leds it has per wattage, the worse it is.

    don’t buy bulbs with 5mm leds unless you need a night-light. and even then, spending 5$ to save 3watt might not be the most efficient place to start conserving.

    incandescents like it hot, fluorescence like it warm and leds like it cold. so a bulb designed to minimize surface and keep the heat in is the worst possible shape for leds. high wattage strip lights are much easier to cool and should last longer.

  12. kabukicho2001 said, says:

    Hi what’s that SMD chip?

  13. Sven says:

    I would like to point out that this is not how a proper LED bulb power supply is designed.

    A proper supply would have regulated current, input filters, a switching supply (not capacitive) and it would be machine soldered.

    Also using a million billion 5mm LEDs is much more expensive, environmentally unfriendly and inefficient than just using a modern high power LED. The only reason these are so cheap is that really badly made chinese 5mm LEDs are dirt cheap. The problem here is that they are all in series, if one breaks the circuit they will all go out. And if a few break in the ordinary fasion (they short out) that will cause a cascade that will short all the LEDs and possibly setting the “power supply” on fire…

    Stop buying cheap multi-5mm-LED bulbs on ebay. At least get the ones with a few 1W or 3W LEDs, they need to have a semi-proper supply that is less likely to fail or burn your house down.

  14. Chris says:

    Nice dissection and writeup.

    I’m pleasantly surprised it was only drawing 9.45mA. The few I’ve purchased, and eventually torn apart were running at 25-30mA. Which produces more light from fewer LEDs, but greatly reduces their lifespan; with noticeable loss of light in a year or less.

  15. Stendall says:

    ¿25:20 minutes long?
    C’mon you can make it longer.

  16. Dax says:

    That’s not anywhere near a 40 Watt lightbulb in output. 2 Watts in is roughly 10 Watts equivalent out for that type of LED, and that’s pushing it.

    The problem is that the human eye is a very poor judge of relative brightness because we have this shutter in the eye that adjusts to the ambient light, so you can easily have a light output 1/3 less light and nobody will notice. People just start squinting at things more and cleaning their eyeglasses or complaining about headaches when the light levels go down, because they can’t see as well.

    It only becomes apparent when you put an actual 40 Watt bulb next to one of these and see that it’s completely dwarfed by the incandescent bulb.

    I’ve been to the homes of people who use exclusively LED lighting, and you should see the astonisment when I take a regular 60 Watt bulb and screw it in instead. It’s like “holy glory that is bright”. Well, it is, relatively, when you’re running half the lumen output with the LEDs from what the advertisement on the packet lets you believe.

    • Malikaii says:

      -Shutter +Iris

    • ironsmiter says:

      I’d agree… sort of.

      The BIG difference I have observed in my little test group(3 households worth of people), has been the directionality nature of the LED’s.

      Accent lighting tends to be loved. Task lighting too. General ambient lighting goes to the old Edison bulb every time. Some of the NEW expensive LED bulbs are much better(The Philips L-prize bulb are JUST NOW becoming available in local brick and mortar stores. And at a relatively cheap $20… and GREATLY enhanced longevity vs the cheaply made lights previously available. We will have to wait and see)

    • ironsmiter says:

      for anyone wanting to do their won teardown…

      Skip the dangerous and highly destructive hammer-method.
      Instead, make a small cut in the sheet metal of the bulb base, and peal it away.
      In addition to what the OP recovered, you should be left with a (hopefully) intact glass bulb and the glass base-pin insulator. and NOT have broken glass all over your shop.

  17. Mister X says:

    Thanks for the tear down info, I’ve always avoided that style of LED bulb because I suspected they were the cheepo-cheepo kind.

    I’ve relamped my whole house save for a Halogen in the kitchen (which will go too), using the Lights of America LED bulbs that I pick up at an outlet store quite inexpensively, so if one is bad it’s hardly a big cash outlay, and so far I’ve had one bad bulb.

    And I pay close attention to the Lumen rating and place lower lumen bulbs in places where high lumens aren’t needed like the central ceiling fixtures in the bedrooms laundry room and bathroom, and for task lighting I use a higher lumen rating in those fixtures.

    I’ve been a residential lighting designer for 30 years and I can say that many if not most people, over lamp (wattage/lumen wise) their light fixtures and waste energy attempting to replicate Sunlight indoors.

    As far as Dax’s comment, perhaps your “friends” have inferior/cheap and/or early low lumen design LED bulbs, or weren’t aware of Lumen ratings and mislamped, because well manufactured higher lumen LED bulb’s work just fine, and humans really don’t need to replicate Sunlight indoors to function, so your friends were satisfied with the lumen levels produced, and your “demonstration” is really just an ego thing for you.

  18. alxy says:

    A decent cree xlamp LED emitter costs about $10 (cree xr-e r2). That’s just the emitter alone. The problem with these are you need a much more beefy power supply, proper heat sink, and possibly a fan. If you want an LED-based lighting solution, screw-in Edison bulb replacements are just not very cost effective. The LEDs go dim, the “white” becomes blue or pink, capacitors leak, diodes short. If you’re serious about LED lighting, think bigger project, like LED-based fixtures, lighting tracks etc with name-brand emitters and replaceable PSU’s.
    As to manufacturing, when it comes to LED’s, think China. Quality is always suspect, cheap or expensive. But they use them over there a lot too.

  19. echodelta says:

    It comes down to this. Bulbs have to go, their shape dictates how much power they can handle. A heavy heatsink is more than that Edison socket with it’s aluminum shell and two rivets was meant to hold. That’s no go for a hand held trouble light, CFL’s make decent work lights cept for RFI.
    It’s time to skip the Edison socket altogether. No insurance or Underwriters Labs would accept such a terminal connection today if new and introduced to the public.
    Another technology oncoming is panel emitters, that will settle the issue.

    • ironsmiter says:

      I think you nailed it on the head.

      To efficiently(cost AND energy wise)switch the population at large to solid state lighting, we’re going to need to toss out the old, and bring in the new. Or at least phase-out the old.
      Set a standard for 12VDC wall outlets, and suddenly the path toward solid state lighting becomes very clear. Even a 5V socket would be good (I already run task lighting on my keyboard, from USB power. A reading lamp should not be much different). Fortunately, they DO make a 120+usb socket now ;-) So far, I’d only use it for charging my phones, cameras, usb flashlights, etc. But much like the iPod socket, once it goes big “they” will make stuff for it. Then “we” will buy it.

      Retrofitting leds just doesn’t work.
      but I’ve seen some of those panel lighting modules, and they are AWESOME(if still very expensive).
      I ALMOST got one for the drop ceiling of the dining room, to replace a failed florescent fixture. Then, I priced a new, even more efficient(than the 20 year old failed fixture) fixture from the bigbox store. The LED panel would have to last around 400% it’s maximum rated service life, to break even cost wise.

  20. Sasha says:

    I get really pissed at people who think it is OK to sell this crap. I mean seriously, for the same money, you can buy high(er) quality light bulbs which are ACTUALLY equivalent to 60W, and they don’t pretend to be equivalent to 40W.

    LEDs are really great, and they’re here to stay. People think they suck balls because what they see in shops nowadays is just pure crap. They really do last 50000 or 100000 houfy if used properly.

  21. McGuiver says:

    I just bought a Cooper commercial outdoor wall pack that is a single 10W led chip that outputs over 700 lumens at 5000K color. I love it. It was made in the USA. Yes it was a $130 dollars. You pay for what you get. I looked at Home Depot and Lowes and was very disappointed with the lighting selection. I had to go to my local electrical supply house. I have 90 percent of my house switched over to LED. I have cut my power bill over half just switching out lighting. Good quality LEDs cost. The other half of my bill was cut with solar panels tied to the Edison. Yes efficiency cost. I avoided those cheap LED laps at the big box stores. I agree that those 5mm LEDs are worthless. You need a Cree chip in the hight efficency and bright LEDs.

  22. ironsmiter says:

    a big issue I’ve had with that sort of light is very poor binning. As a trial, I picked up a 5-pack for the vanity lighting. all 5 failed relatively quickly… 2-3 months.
    All 5 circuit boards were STILL GOOD?!? shocked me too. In each case, ONE of the leds had failed, taking down the entire chain.(why oh WHY don’t they make these a higher current parallel circuit, instead of a higher voltage serial circuit?)

    My “repair” was closer to re-manufacturing.
    I tested each led individually with a constant current/voltage power supply.
    Half to three quarters of the leds in each bulb were a close match. The remainder, I swapped around for matching leds from one of the other bulbs.
    In the end, I now have three good bulbs, using matched leds. Going strong for over a year, with no sign of deterioration. Also, a small collection of mismatched yellow/white leds, ready to serve as indicators in a circuit, or throwies, or whatever.

    If the manufacturer had done A LITTLE quality control before hand, they could have easily made a bulb worth 3 times it’s asking price.

    Now, MOST of the more expensive led bulbs use surface mount leds, with a substrate that can act as a heat sink of some kind. Also, they are much better binned for the multi-led designs. but you sure pay through the nose for them.

    My MAIN reason for stockpiling incandescent bulbs(besides their reliability http://www.centennialbulb.org/news/ripleys-2011.jpg let’s see an led do THAT!) is actually COST. For JUST the $40 purchase price of a “good” led bulb, I can buy a pack of 60W incandescent bulbs, and run them 24/7 for a full year. Now add the cost of running the LED light, and I’m closer to a year and a half of 24/7/365 lighting before the LED+Energy cost BREAKS EVEN. and guess what? that’s over 90,000 hours of operation. hmm, that’s about twice the rated lifespan of an LED bulb(50,000 hours on the last package I checked).

    The sad fact is, the only ECONOMIC reason to switch from incandescent to LED is… they’re not gonna be making incandescent anymore. Even CFLs fall victim to this logic, though not as badly. A CFL bulb costs 6 times as much, lasts 8 times as long, and is 5 times more efficient(approximately). So, after one year(~60,000 hours) of continuous use, a pack of CFL is saving me money vs a pack of incandescent. But now I have a couple highly toxic mercury laden glass bulb and lead laden circuit boards to try and safely dispose of, instead of an old fashion glass and metal package that can be recycled, SAFELY landfilled, or even re-purposed(http://www.instructables.com/pages/search/search.jsp?cx=partner-pub-1783560022203827%3Anpr2q7v5m6t&cof=FORID%3A11&ie=ISO-8859-1&q=light+bulb)

    [/rant]

    • yamaplos says:

      Oh, centennial bulb!

      For the longest time I had the highest level of disrespect reserved, not for lawyers or Wall Street, but for those “engineers” I believed their job was to figure out the thinnest possible filament for an Edison lamp that would still test and ship, but would fail for sure within a couple years – planned obsolescence.
      Then, thanks to Wikipedia, I learned that thin filaments are more efficient power-wise in producing light, so there is some sort of a justification there. Thick filaments can last a whole lifetime, or several, but produce more heat and less light. So the real engineer has to figure out a balance: a filament that will output a lot of light, and still last some. I can tell you I feel bad for having had, so long, a bad opinion about those guys, though I still hate it to spend time and money replacing the burned out buggers, especially those GE halogens.

      That said, if you want your own centennial bulb, get yourself some foreign Edison bulb that was build for 230 V. Running it in a 120 V circuit it will become a precious keepsake you will be able to pass on to your grandchildren. Nice and cosy for winter, but not that much light.

    • Chris says:

      Actually, 1.5 years of continuous operation is 13,140 hours – not over 90,000 as you stated. So payback and savings are possible with the LED light, assuming it doesn’t fail or degrade prematurely.

      • ironsmiter says:

        Sorry, you’re right… for some reason, I added a x7 in there when doing my maths.
        (I was clearly thinking 24/7/365 and used those numbers in my maths, instead of 24/365)

  23. NewCommentor1283 says:

    he is just saying what ive been saying to people in person for years. lolz

    with LED’s its like the power amplifier in your high-powered stereo, they are both semiconductors…

    its not you get what you paid for, even though it may be coincedentally true,

    its: YOU GET WHAT THE MANUFACTURER WANTS YOU TO HAVE !!!

    … NOT what you want to buy! and thus;
    DO NOT EVEN READ THE PACKAGE

    … go straight to digikey or mouser, or anyother place that wants to sell a juicy 1W or 10W LED that COMES WITH DATASHEET !!!

    you having a datasheet in hand (and following the datasheet to a “t”) is what makes a suitable LED lamp!

    also, buy a matching HEATSINK unless you intend on ONLY using it in sub -20c weather AND at 10% brightness.

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