Oldies but goodies!!!

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Who said big old electrolytics don't age well?

I made some tests on really vintage caps, in particular a Rubycon 1000µ/65V from the late sixties.
It's a monster 35mm in dia., 52mm length (see photo).
At 1KHz, the measured esr was a respectable 61.5mΩ.
As a comparison, a recent Nichicon 1000µ/100V type PR(M) measured 41mΩ, and a SC 1000µ/35V 71mΩ.

A 1600µ/64V from MBLE, practically contemporary of the Rubycon measured 29.5mΩ, a Siemens 1000µ/40V made in Austria in 1973 was at 33.5mΩ, and a F&T 1000µ=1000µ/100V from 1983 was at 42mΩ (probably one of the last to be made for chassis mounting).

Never take anything for granted!
 

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Where have these caps been the last few years and/or decades? In operating circuits (getting powered up every once in a while), or sitting in a drawer (or in equipment that's been sitting in a box for years and years?

Have you reformed them? I wonder if reforming makes a difference.
 
How hot have these survivor electrolytic caps been? We had an organforum member pay a premium for a 1971 organ because it sounded so good in the flea market. The good sound lasted about a month, until the water vapor pressurized the rubber cap seals and leaked out. Now his sounds like a kazoo, like mine did before I replaced 70 capacitors. If the cap is not used, the water vapor pressure is very low.
On the other hand, some capacitors were not sealed with rubber. The datasheet might give an "hours expected life" but who has a datasheet for a 1969 cap?
Do a real experiment. Put the good caps in an evironmental chamber for a month at 60 deg C and tell us the numbers at the end. A weight of each before and after would be very instructive, also.
 
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Where have these caps been the last few years and/or decades? In operating circuits (getting powered up every once in a while), or sitting in a drawer (or in equipment that's been sitting in a box for years and years?

Have you reformed them? I wonder if reforming makes a difference.
They have never been used, and have been stored all that time in gentle (5°C<T°<35°C) conditions.

They haven't been reformed, but regarding esr, it would make very little difference: at most, a small increase.
I can reform them and measure thereafter. I am sure they will work normally, I have already used a good number of them in various projects, without even taking the trouble to reform them, and they worked perfectly, they woke up like the sleeping beauty, in pristine condition.
The Siemens in particular are amazing: they beat hands down modern radial low esr lytics, and they are just axials.
German (or Austrian) quality was something you could rely upon.
 
How hot have these survivor electrolytic caps been? We had an organforum member pay a premium for a 1971 organ because it sounded so good in the flea market. The good sound lasted about a month, until the water vapor pressurized the rubber cap seals and leaked out. Now his sounds like a kazoo, like mine did before I replaced 70 capacitors. If the cap is not used, the water vapor pressure is very low.
On the other hand, some capacitors were not sealed with rubber. The datasheet might give an "hours expected life" but who has a datasheet for a 1969 cap?
Do a real experiment. Put the good caps in an evironmental chamber for a month at 60 deg C and tell us the numbers at the end. A weight of each before and after would be very instructive, also.

I'll try to hijack one of the chambers at my work for some time....

As I said, I have actually used those caps in various projects, and some of them (lab supply, etc) have been used almost daily for more than 25yrs.
I am less sure about the F&T's: I do not have such a long term experience with them, and I am not too confident about the thermosetting threaded end.
 
Who said big old electrolytics don't age well?

I made some tests on really vintage caps, in particular a Rubycon 1000µ/65V from the late sixties.
It's a monster 35mm in dia., 52mm length (see photo).
At 1KHz, the measured esr was a respectable 61.5mΩ.
As a comparison, a recent Nichicon 1000µ/100V type PR(M) measured 41mΩ, and a SC 1000µ/35V 71mΩ.

A 1600µ/64V from MBLE, practically contemporary of the Rubycon measured 29.5mΩ, a Siemens 1000µ/40V made in Austria in 1973 was at 33.5mΩ, and a F&T 1000µ=1000µ/100V from 1983 was at 42mΩ (probably one of the last to be made for chassis mounting).

Never take anything for granted!
I subjected the caps to a quick formation (direct connection to a 100V supply, except for the 40V which was only allowed 65V:D)

Results: Rubycon is now at 65.5mΩ
1600µ: 27.9mΩ
Siemens: 33.5mΩ
F&T: 40mΩ

As expected, no significant change.
 
would you mind sharing the design ?
No problem.
There are two versions: one, the "lab" variant, applies a DC bias to the capacitor under test, the other is the "workshop" version, for in-circuit testing, but without DC-bias.
One could easily combine both with just a switch.

For more details, and other similar test gear, you can go to: Testeur de condensateurs électrolytiques.
It is in french, but this shouldn't be too much of an obstacle for you (at least, I hope so).

Note that these are true, vectorial esr meters, not mere AC ohmmeters.
 

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this picture is the box that has inside about 2.500 small capacitors and about 100 of bigger ones

represents work of latest 8 month
( one of my employees started to collect them in order to know how many capacitors we had to replace in a year's time )

i think its going to be over 4.000 by the end of the year

If you like to have them for more investigation i may as well ship them to you ...

kind regards
sakis

100_2036.jpg
 
this picture is the box that has inside about 2.500 small capacitors and about 100 of bigger ones

represents work of latest 8 month
( one of my employees started to collect them in order to know how many capacitors we had to replace in a year's time )

i think its going to be over 4.000 by the end of the year

If you like to have them for more investigation i may as well ship them to you ...

kind regards
sakis
Thanks, but I already have more than enough material to carry out tests and statistics.
 
No problem.
There are two versions: one, the "lab" variant, applies a DC bias to the capacitor under test, the other is the "workshop" version, for in-circuit testing, but without DC-bias.
One could easily combine both with just a switch.

For more details, and other similar test gear, you can go to: Testeur de condensateurs électrolytiques.
It is in french, but this shouldn't be too much of an obstacle for you (at least, I hope so).

Note that these are true, vectorial esr meters, not mere AC ohmmeters.


Excellent !!!! Thanks a lot Elvee !
This goes directly in my schematics treasure box and bookmarks !

For once being french is an advantage on DIYaudio!
 
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