In my so-far practically 30 years of writing for EDN, I’ve realized so much about my ever-evolving viewers (i.e., you), at the least two facets of that are immediately related to this explicit writeup:

• You love consuming any content material that’s even remotely LED-related, and
• I’ve just about given up making an attempt to determine what matters will particularly entice your consideration, except for relying by myself curiosity as a information to what you may additionally like.

Take, for instance, my not too long ago printed teardown of a LED-based desk lamp. In comparison with another teardowns that I’ve performed, it was fortunately pretty speedy and simple to each implement and doc. However, judging from the amount and element of the feedback already posted on it, I’m guessing it’s nonetheless driving a variety of “eyeballs” to the EDN web site. A fading-illumination-intensity-over-time LED apparently piqued extra than simply my curiosity.

The LED mild bulb that remodeled right into a sorta-strobe mild

Or take as we speak’s dissection candidate, a standard LED mild bulb that had begun not fading, however as a substitute, flickering. As historic background, I’ll take you again 9 years to after I took aside my first LED mild bulb, two dimmable examples of which had prematurely failed, resulting from (I prognosticated on the time) prolonged publicity to excessive temperatures attributable to poor air flow of the ceiling-mount enclosures inside which they have been put in. On the time, a reader named “docterdon” famous that I hadn’t described these sconces, so within the spirit of “an image paints a thousand phrases”, right here you go to start out:

The room change controlling the lights wasn’t dimmable anyway, so on the time I went forward and changed all of them (together with the 2 still-functional ones, which I ended up reusing elsewhere) with CFLs. Two of these ended up prematurely dying too, so as soon as once more I swapped them out for LED bulbs, non-dimmable this time (I used to be admittedly shocked to appreciate, when not too long ago reviewing previous printed teardowns, that within the plethora of LED-based illumination sources I’ve taken aside lately, a standard non-dimmable one hadn’t but gone below my knife). They got here eight to a package deal; right here’s the encircling cardboard label:

Behind it in every initially shrink-wrapped assemblage, 4 of which my e mail archives point out I’d promotion-purchased from VMInnovations again in October 2018 for $9.99 complete, have been two containers, every with 4 bulbs inside (sure, your math is true; that interprets to $0.31 per bulb!):

Right here’s our flickering sufferer, as regular, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for measurement comparability functions:

Shifting the bulb barely to the left, right here’s your reminder that my workplace desk is perpetually bathed by the sunshine coming from—amongst different issues—the front-panel blue (when the pc it’s related to is powered on, that’s; in any other case white) LED of the growth hub tethered to my Mac mini, whose illumination you’ll see in a few of the pictures that comply with:

Diving inside

Onward; let’s get the globe off. Prolonged publicity to my spouse’s hair dryer didn’t assist a lot with loosening the adhesive; then once more, not like what my warmth gun had performed prior to now, it didn’t deform the globe itself, both. However, utilizing a number of “spudgers” and aided by loads of “elbow grease” and “colourful language”, I lastly wrestled the globe off the bottom:

Admittedly, within the course of, snapping one of many three resistors off the plate, together with scraping the phosphor cap off one of many LEDs:

That giant IC you see at heart left is the RM9003T, a high-voltage single-channel fixed present LED controller from Shaanxi Reactor Microelectronics. That stated, from previous expertise, I strongly suspected that what I used to be at the moment seeing wasn’t the total extent of the circuitry; there was doubtless extra behind the plate. There’s just one method to discover out for positive:

At this level, my ahead progress was stalled till…ah, sure, these energy wires working to the cap finish have to be disconnected earlier than I can fully take away the plate. Time to dig out my tongue-and-groove, slip-joint (aka, “Channellock”) pliers and wrest it off…

Figuring out the Achilles heel

That’s extra prefer it:

The markings on the IC on one aspect of the now-exposed underside PCB:

are barely discernible:

MB6S
1607

It seems to be a miniature surface-mount bridge rectifier, changing (crudely) AC to DC together with the 390 kΩ (“394”) resistor subsequent to it and the 200-V 10-µF aluminum electrolytic capacitor on the PCB’s different aspect:

Talking of enclosed areas with inadequate airflow and consequent overheating potential (generated by the multi-LED array on the plate above it), I’m guessing that right here’s the place the flickering originates. Agree or disagree, readers? Share your ideas within the feedback!

—Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line publication.

 Associated Content material

• Teardown: What killed this LED bulb?
• The empty promise of the LED bulb’s lifetime
• Disassembling a LED-based mild that’s not appearing fairly proper…proper?
• A short historical past of the LED
• Liberating a three-way LED mild bulb’s insides from their captivity

The put up Diagnosing a flickering LED mild bulb appeared first on EDN.