[rescue] Slightly OT: Bad Cap Saga

Geoffrey S. Mendelson gsm at mendelson.com
Mon Aug 18 10:33:46 CDT 2008

On Mon, Aug 18, 2008 at 07:45:38AM -0700, Luke Goembel wrote:
> I build electronic devices that are 
> meant for use in space. 

I love to read posts like this, because while I understand that there
really is a space program of some sort left (I was at Cape Kennedy to
see Apollo 14 lift off), and a lot of commercial use of space, it's
good to hear from people who are actively working on it.

> Clearly, electrolytics are the week 
> link in many consumer electronics 
> and have been for decades. In fact, 
> I recall that in restoring old 
> television sets from the 40's it 
> is reported that replacing all the 
> old 'paper' capacitors with new ones 
> is often all it takes to get 60-year 
> old electronics running again!

Not to contradict you, but most of those capacitors are not electrolytic at
all. Most of the electrolytic capacitors of that era are in steel cans. 
They also explode when subject to full voltage after long periods of
disuse, but the explosions are, due to the steel cans, more like a vent popping.

The worst offenders are Sprague "Black Beauty" capacitors which were coated
with some sort of black plastic and supposed to be better than anything on
the market at the time. The black plastic decomposed rapidly and some
of them failed to last. In some cases, the equipment was still being 
manufactured when the first ones failed.


Geoffrey S. Mendelson, Jerusalem, Israel gsm at mendelson.com  N3OWJ/4X1GM

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