William Sommerwerck wrote:

Because electrolytics are heated internally in most SMPS
(secondary side) applications, I wouldn't think extra venting
or supplemental cooling with a tiny fan would add much
toward the caps' lifetimes... they're just destined to fail.

One tends to think of electrolytics as /inherently/ failure-prone. But has
this always been true? Or are you thinking just of switching and/or "tightly
packed" power supplies?

I've been buying electronic equipment, used and (mostly) new for 45 years,
and very, very few items have had bad 'lytics, or 'lytics that turned bad. I
remember a used KLH compact stereo that needed new caps, and two JVC hall
synthesizers that needed replacement PS caps. (The latter had been built
with known-bad caps.) And that's about it.


Most of that equipment had a better grade of electrolytics. The
imported stuff is crammed into tiny containers which can't disiapate
much heat. Low ESR caps in switching power supplies have to be very
close to both the recitifers, and the load, so they are in a hotspot,
which further reduces the reliability. Some CPUs draw over 100 A at
less than 2 Volts. If the CPU power supply was on a corner of the
motherboard, the voltage drop would waste a lot of power, and create
more waste heat.



I owned several KLH Model Eight table radios (circa 1960), and none ever
needed a new 'lytic.


Sprague, Mallory ore CDE electrolytics? Maybe Sangamo.


On a vaguely related note... It's nice to see that more and more products
are coming with switching wall warts.


Except when they radiate a lot of RF noise.


I recently had a small accident with an RCA/China VR5220-A
pocket digital voice recorder, where it slipped into the sink while
the water was on, so I opened it to get all traces of the water out.
I was just a little surprised to see 105 C rated electrolytics inside
(all of 'em, and quite a few, too).

Perhaps the manufacturer used premium caps in all its products, simply to
avoid multiple inventory.


Or they are cheap, no name Chinese fakes.


--
For the last time: I am not a mad scientist, I'm just a very ticked off
scientist!!!