Spontaneous LED bulb teardown — IKEA 200lm candle #2

Not too long ago one of these darn IKEA LED lamps (200lm, 4.3W) broke down after very mild usage. Well… it has happened again!

When I went into my bathroom one or two hours ago, I thought I was going blind, everything was so dark. But it was the friggin’ lamp…

IMGP11317

The power supply looks fine – just like the last time.

IMGP11324

No burn marks, charring or blow holes. Nothing!

IMGP11326

This time I made an effort to pull all parts off the PCB intact – to check them. I managed to do just that – with two exceptions: the inductor broke (again, see last time), the controller IC (no way to check it).

IMGP11327

Empty PCB with a bit of the inductor that didn’t want to come off.

IMGP11330

The transformer.

IMGP11331

I tested all windings. As far as inductances go, they were all below 5mH. My meter doesn’t go below that. The resistances were fine. The secondary going to the LEDs had 52mR, the other windings 179mR (maybe feedback) and 1.784R (probably primary). All in order.

List of measurements, everything looked fine and in spec.

IMGP11334

Bag of parts ready for the recycling center

IMGP11335

Last but not least – as previously reported on this blog – the LEDs are still fine!

IMGP11323

Is this planned obsolescence or just plain old failure by design?


In response to Jkx’s comment:

IMGP11338

LNK605DG_01

LNK605DG_02

LNK605DG_03

LNK605DG datasheet

Measurements:

The built-in power MOSFET (n-ch) may still be OK. No conductivity between D->S, S->D conducts via its body diode (0.538V), as expected.

There is a resistance of about 500kR between the BP and S pins and a clear diode action, which may be alright, as there is a Zener diode in there. There are some signs of life of the internal 6.5V Zener diode. Reverse-biased current markedly increases at about 7V.

The FB pin behaves similarly, but with different resistances. Resistance between FB and BP is several MR.

The power MOSFET seems to be OK, the Zener diode may still be OK, the rest… who knows. Given that all other discrete parts seemed to be in good shape, the conclusion must be that either the infamous inductor or the control logic in the chip are the cause for this repeated failure.

This entry was posted in Electronics. and tagged , , , , , , . Bookmark the permalink.

7 Responses to Spontaneous LED bulb teardown — IKEA 200lm candle #2

  1. Jeff says:

    Guessing bad design. Might be too late for yours [cough] but I imagine Ikea would replace them if you brought back yours; they do seem to be defective.

    • robert says:

      Nope! Been there, done that.

      As far as local warranty laws go, they’re off the hook after 6 months! EU laws say the warranty period is 24 months, BUT after 6 months the customer needs to prove that the product was already faulty when purchased. For all intents and purposes, this is nigh impossible to do – unless you show up with truckloads of prematurely deceased devices.

      I had a longish discussion with one guy at my local IKEA and they don’t seem to be into “goodwill” replacements. No use arguing, waste of time.

      Of course these bulbs are crap! My parents have a couple of 8W Philips LED bulbs (used to cost 35 bucks each), which run for many hours each day. And they’ve been doing that for a couple of years now.

  2. Jkx says:

    Hi,

    I’m quite sure the LNK IC died. You can test it easily : Check for shortcut in the IC.
    This IC are really fragile. Some of them are used in general electronic devices like washing machine.. I fixed a couple of this.

  3. Mattias says:

    What is the on/off cycle specs of these lamps? We have an automatic lamp in our wardrobe that we open/close about 10-20 times a day. We got many broken LED-lamps – the didn’t last more than a 9-10 months (I used a marker to write the date of replacement on the lamps).
    Then I checked the specs of the last lamp we bought. It says > 10000 h or light, but only maximum 3000 on/of cycles. I don’t know the traffic to/from your bathroom but I guess it is the on/off cycles that kill these lamps.

    • robert says:

      If they can only withstand 3000 on/off cycles, then this is clearly planned obsolescence / bad design. In both cases, the LEDs themselves were still fine, but the power supply was dead. This is a huge generator of E-waste and IKEA have refused to replace LED lamps before (400lm one). They seem to know about this and don’t support their own product.

      I think this is a deliberate rip-off.

      • Mattias says:

        I checked my stock of old LED labs (we don’t like the colour temperature and are instead using lamps with the small halogen bulbs inside – shame on us!). The old ones (probably 4-5 years) say 3000-5000 cycles. One Osram E14/11W claims 10000 cycles and 10000 hours. However, checking IKEA’s website their LED lamps claim 15000-25000 depending on model. Clearly they have better specs (new standards for testing?), but in real-life no so…
        You definitely have a case!

  4. Pingback: LNKは壊れやすいってさ – OnBoard PRESS Japan

Comments are closed.