I just took apart a failed LED bulb replacement. The circuitry appears
fairly complex using caps diodes and active components Complex
relative to a circuit that is just a rectifier and current limiting
resistor. While the LEDs themselves may have high reliability I think
the failing point is going to be the power supply and I am not
expecting them to have much better reliability than CFLs. I do think
there is a future for home LED lighting that will come when buildings
are wired for low voltage lighting that removes the 120 VAC to low
voltage DC power supplies from the bulbs.
That sounds better made than most christmas light strings which are
nothing more than a bunch of LEDs series wired, with (possibly) a
resistor ahead of the first LED in the string. I had one of them fail
this year, the string of around 100 lights is in 3 parts and one part
failed. I found 3 bad LEDs.
In your light, I'd check the diode rectifiers at the input from power
line, and check the capacitors. All this can be checked with a
multimeter. The diodes should read high resistance in one direction,
and very low the other way (reversed test leads). If you get zero
ohms both ways the diode is shorted, if high or no resistance both
ways, it's open. They can be replaced pretty easy, Radio Shack has
them, get one rated at least 200volt and one amp (which well exceeds
Caps should not be shorted. A multimeter should show the meter or
digital readout spike as the cap charges. No resistance or no spike
means it's dead. Reversing the leads will cause a second spike.
These are electrolytics, so the red lead really should go on the +
marked side of the cap, but reversing them with a meter wont harm
them. However in the circuit, they MUST be wired so the + goes to the
Of course, look for loose solder joints and anything that looks burnt.
I'd be interested to see a photo of the innards of that light. Can
you take a photo and post it to one of them free photo sites?
Of course post the URL on here afterwards.
No, but it can be much better quality using a transformer or a
switching power supply, ( very efficient) and not have to be
duplicated for every light. We have low voltage power supplies that
have been running for 20+ years 24/7.
Wait a minute, every electronic device in your home has a power supply
that converts 120Vac to a lower voltage DC (unless it's an old vacuum
tube device). This includes computers, tvs, radios, cd/dvd players,
vcrs, stereos, etc. The power supply in these dont fail on a regular
basis. Apparently these LED lights are using inferior components in
their power supply, not to mention being made in China. For one
thing, each one should have a surge supressor. And the CFL lights are
not much better. I've had two of them blow sparks and smoke when they
fail. Once again, cheap components and made in China.
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