It was to happen sooner or later. First LED lamp we've used pretty much died. Not completely, but it started to turn on and off randomly (not exactly flickering as it kept on or off for longer periods) which was annoying enough so I took it off and replaced with a new one.
Here it is. No-name brand, but I've taken a habit of writing date and place of purchase on the lamps (well, LED and CFLs, you can see tails of text on glass at left) when I put them in use. The date on this was march 2013, so I got about three and half years of life out of it. Of course it's out of warranty by now.
I have no exact figure but I guess this might have been used maybe four hours a day in average, which would put it around 5000 hours or so total. Not exactly a great figure for a LED lamp, actually. However the actual figure might be double that, too, I really don't know for sure as I haven't really kept record of lighting usage at home.
Being a curious person with some time on his hands I decided to see what's inside.
First problem is of course how to open it. After some unsuccessful attempts with a knife (round objects like this and knife is kinda dangerous combination, one slip-up and there will be blood...) I put it in vice grip and just grabbed the glass (with thick gloves on, naturally) and twisted. Something gave - and it turned out to be transformer coil and plastic mounts inside.
Although the glass and heat sink look and feel like plastic, they actually are glass (as I found out when I tried to twist it off - I survived that breakage without damage) and aluminum. The heat sink is anodized so just probing it with multimeter doesn't work (and your fingers should be safe when it's on, but I wouldn't touch it anyway when on), but if you scratch the oxidation layer off the bare metal is exposed)
The main board, with transformer placed in its usual position again. The "isolation slot" there is pretty much for show only, it doesn't really isolate anything; you can see leads going to led under the transformer coil there. Any high voltage isolation here happens purely inside the coil, and since I have no means to judge the construction I can't really say anything about that.
Although it is difficult to see from picture, the flux residue on board is pretty bad. There's nothing obvious that would explain its failure though. Caps haven't leaked or swollen either.
The chip in the middle is LNK613, which happens to be purpose-made CV/CC controller. Rest of the board (and LED board) are pretty much exactly the same as the example given in chip datasheet (no surprise there), and I didn't feel like analyzing it in detail so nothing more about that.
Led board (metallic for heat dissipation) has resistor, capacitor, diode and the LED itself. So simply the parts needed to be on the secondary side of transformer by example circuit.
So this is what you might find inside a four-year old LED bulb. Not the cheapest construction I've seen so far, but not the best either. At the moment I'm waiting one of the dimmable LED bulbs to burn out so I could see what they've eaten... Although I don't expect much more than this, maybe with just a slightly different chip in the center.
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