I've been poking at a troublesome 5 disc cd player for a months now. It's a Sony from the early 90's. And it's basically been plugged in to the wall since 1995, except for some years when it's been unplugged all winter. And the only power switch is for the 5V logic rail, the rest has been powered.
All the voltages are fine at least, but I went ahead and checked all the electro-caps, mostly nichicon, and Elna. And they are all still great compared to an average ESR chart, and they are fine for the dissipation factor in the datasheet too. I mean it's not like they're the age of Great Pyramids, but I figured they would have been a lot closer to borderline. So if I scrap this thing, there's some free caps at least.
There's lots of sub 1uF radial through-hole caps everywhere, ceramic's I guess. I hope they are holding up as well.
I've been chasing some intermittent door/sled problem, as well as jamming, or motor failing, or motor controller failing. I better pay closer attention to some of those small caps. Its not the 1 on the open/close button anyways.