In article , Jeff Wisnia says...

Robert Swinney wrote:
So Jim, what are the electronics for? I sorta figured the new LEDs used
(only) appropriate dropping resistors like older conventional LEDs.

Likely it's a dc to dc converter of some sort, much more efficient than
wasting power in a dropping resistor. I'm amazed at the kind of
efficiencies I see claimed in chip manufacturer's ads these days.

Jim just confirmed what I've been saying for the last ten years or so,
repair of consumer electronics has become more of a mechanical job than
an electronic troubleshooting one. The parts themselves hardly ever fail
these days, it's mainly "loose disconnections" that keep the parts from
doing their intended tasks.

The electronics are two transistors, a couple of resistors, and a
flyback inductor, to boost the voltage so that a white LED that takes
four volts to turn on, can be run off of two AAA batteries that only
make three volts.

Now if I only could have found the loose connection that made my
daughter's cell phone stop working - not that I didn't inspect
every bit of the board under a microscope for an hour or so!

Jim


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