Spontaneous LED bulb teardown — IKEA ledare 400lm

I bought this LED bulb about 21 months ago for €11.99.

23384543.96d8d0a5

I liked it!

Now, you’ve certainly noticed that I used the past tense in the previous sentence. It failed a couple of days ago. Today I tried to have it replaced at IKEA, but they refused. Yes, there is a 24 month ‘warranty’ in the EU, but the WEASELS have ways to wriggle out of that. At least if you don’t want to involve a lawyer over just 12 bucks.

How long did it last? Well, less than 24 months, duh. If I use a conservative estimate of about 1-2 hours of operation a day, that translates into somewhere around 1000 hours. A surprise, maybe not. Very far from the numbers usually claimed, which are in the 10’000s of hours.

This bulb was marketed as a 60W equivalent. With a kWh price of about €0.26, the bulb has payed for itself, barely.

Symptoms: excessive heat, shuts down on its own (presumably over-T protection), very bad smell emanating from the bulb.

I didn’t manage to remove the LED carrier, too much epoxy.

IMGP9115

Texas Instruments TPS-92070-based. Interesting thing, using isolated current sense feedback using a small transformer.

IMGP9121

It looks like there might be a crack in the capacitor, but it’s OK.

IMGP9120

IMGP9119

The large transformer is used for DC/DC conversion, the small one provides isolated LED-current feedback. See the datasheet for some details.

IMGP9118

IMGP9117

IMGP9116

I suspected a blown capacitor, but I didn’t find any of that! Except for the bad smell, I didn’t find anything obvious. Fortunately the LEDs are still OK (350mA-ish @ 16V-ish). The lamp should take 8.1W. The power-supply has an efficiency of about 80% (see datasheet), the LEDs should take about 6.5W (about 400mA). The current-sense resistor of 240mOhm + the current-sense threshold voltage of 100mV give about 417mA, looks OK to me.

IMGP9122

I’ve removed the E27 connector, just to be on the safe side. The hole at the bottom will come in handy for adding a barrel connector.

I think I will convert this bulb to a low-voltage lamp at some point in the future – using my favourite PT4115 constant-current LED driver with an external power supply. After removing the old power-supply, there is enough room for adding a small circuit board with that driver, a micro and maybe 2 buttons for brightness control.

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4 Responses to Spontaneous LED bulb teardown — IKEA ledare 400lm

  1. ewertz says:

    Hope you didn’t buy another one, given that they didn’t stand by the first one.

    Cree started selling 800lm@9W screw-in bulbs at retail in the US for US$10/11 for warm/neutral, so it seems like you could do better nowadays, even with the euro-markup.

    However, in the interests of science… carry on!

  2. robert says:

    I have a couple of other IKEA LED-lamps, but different models. A few of them are low-power ones for night-desk lamps. So far they work fine and get much more on-time as well.

    My latest additions to the LED-lamps are two 10W 600lm ones.

    Review: https://www.youtube.com/watch?v=3wqTsUcLnUs

    They run pretty hot as well, but only cost about 7 bucks or so. Efficiency is not particularly high, but with the amount of on-time these get, they pay for themselves in about two months.

    Now, if they used high-efficiency Nichia LEDs in these (up to 120lm/W), they could down-size the power-supply, get more light and increase life-time. But these things are quite costly, but I guess IKEA would get a much better price on them than me ;-)

  3. Helmut says:

    Hi Robert,
    die 5 LED-Lampen von dir leuchten immer noch.

    Gruss Helmut

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