On Thu, 02 Feb 2017 18:36:08 -0800, Jeff Liebermann
wrote:

On Thu, 02 Feb 2017 16:44:53 -0600, wrote:

I'm 66 years old. According to my doctor, I dont have any bad
capacitors, (just arthritis).

I'm 69 years old. My body mechanic says I have pump and inside
plumbing problems. Perhaps I should replace him with a plumber?

Definitely sounds like you need a plumber

Seriously, I wonder what the life expectancy is for the new caps
(meaning the replacements for the wax coated paper caps. ???)

There are online lifetime calculators for electrolytic and other types
of capacitors. For example:
http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx
http://www.chemi-con.com/education (click on Capacitor Life)
The major culprit is internal heating from high ripple current
resulting the electrolyte leaking or evaporating. Temperature also
has a big effect. There are graphs on the capacitor data sheets that
approximate the lifetime characteristics.

OK

And what are these newer ones made from?

For electrolytics, try polymer caps:
https://en.wikipedia.org/wiki/Polymer_capacitor#Lifetime.2C_service_life
http://www.mouser.com/pdfdocs/Panasonic_Capacitors_WP_final.PDF


So, what are the BEST ones? For example, I am getting a Hallicrafters
sx-99 radio, to recap it, what should I use for the small caps (not
electrolytics)? Should I use the "orange drops", or is there something
better? I'd rather spend a few bucks more and get the best.

By the way, why are all the caps now rated at some oddball figure.
For example, instead of .05, it's ,047? or instead of .003 it's .0033.

Same for the 'lytics instead of 30mf, they are 33mf and so on.....

I know the mica and ceramic caps are reliable and last almost forever.

Not all ceramics are that reliable. MLCC (multi-layer ceramic caps)
are rather fragile and microphonic.

What do those look like? Are they the ones with colored dots that look
like dominos? (But I think those are mica caps, if I'm not mistaken).

I remember those squarish brown ones with the leads on the bottom, those
were supposed to be superior. (Silver mica, maybe?)

And the round ceramics were said to be good too.

A for electrolytic caps, it seems that the newer ones have a much
shorter life than the old ones did.

Nope. The old ones filtered at 120 Hz. The new caps filter at 100 to
300 KHz. Internal dissipation follows frequency.

Can you explain that. I dont understand...
(I would think that a 'lytic in a power supply would only need to filter
at 120hz, or would some filter at 60hz also, depending on the
configuration?

That's
why those old radios still work after 60 or 80 years, while most stuff
made today is in a landfill in less than 10 years.

Todays products are intentionally designed to be difficult to repair
and to only last as long as the warranty period. With the proper
design tools and models, it is possible to predict the life of an
electronic (or mechanical) product. Anything that lasts longer than
the warranty period is deemed to be "over-designed". It is then
redesigned using lower rating or cost components so that everything
blows up at the same time. I've seen it happen.

I totally agree. You cant identify parts anymore and if you can, you
cant get them. Especially ICs.

In the 60s and 70s, I loved to work on electronics. Mostly tube stuff.
The early transistor stuff was not too bad, but as soon as they began
using ICs, I lost interest in working on it.

Now, 40+ years later, I am gtting back into it, but only working on
antique tube stuff, which is what i enjoy. Modern stuff is far too
complicated, far too small (hard to see with my aging eyes too), and
does nothing but frustrate me.

Sure, I have built every computer I have owned (or rebuilt from parts of
thrown away ones). But with computers you just change boards, not
individual components.

I guess going back to the tube stuff makes me feel young again!