Very old Sanyo OS-CONs. Safe to use?

[quicknick]

Hi folks,

Some time ago I got (for very cheap) a bag of 200 Sanyo OS-CON SA series, 220uF/10V, manufactured January 1988. Measured a few of them and the readings were all over the place so I put them in storage.

Fiddled with them one more time today, to decide if I keep or throw them away, and noticed that strange readings are due to a layer of practically invisible oxide that developed on the leads. Rubbing them just a bit with fine sandpaper or even with the tester probes and they can be tested OK, tried with 10 of them and they mostly measure towards 250uF, with one or two being closer to their rated 220uF, and ESR is about 25-30mohm.

Searched the 'net for information about their shelf-life, couldn't find anything useful. Do you think they can be used after all those years? Is there anything that can dry out or otherwise deteriorate inside them (I suppose they are solid electrolyte)?

[momaka]

Re: Very old Sanyo OS-CONs. Safe to use?

I'm no cap expert, but given that these are solid polymer capacitors, I don't think they will deteriorated as fast or as bad as regular electrolytics. So most likely, they are probably OK.

Before using them for any repairs, though, perhaps take a few random samples and connect to a test circuit. With the test circuit, bring the caps to their full rated voltage (i.e. as close to 10V as possible, but not over) to see if the electrolyte inside starts breaking down and shorts out or not. If none of the sample caps issues, chances are the rest will be fine too.

While at it with the test circuit, though, also check the leakage current on the caps - i.e. see how much current DC current they are drawing once fully charged to max rated voltage. After this, discharge caps, then check ESR and capacitance again to see if anything has changed.

All in all, though, I think they are still likely OK to use.
Curious to see what other people that know more about the matter will have to say (waiting for Wester547 to chime in 3...2...1............ just anytime now )

[Wester547]

Re: Very old Sanyo OS-CONs. Safe to use?

I wouldn't deem myself an expert either, however interested I am in the topic.

But those Sanyo OS-CON capacitors (technically not polymers in the strictly technical sense of the term; they use a special type of semiconductor material for their electrolyte) are very old now. They are ~32.5 years old. And even though they are sealed with epoxy rather than rubber, this is enough time for some precipitation and deterioration, regarding their specifications, to occur. Their leakage current has probably risen quite a bit as is characteristic of solid capacitors (polymers or otherwise). Since such capacitors rely upon electronic rather than ionic conduction, conductivity is usually much better than comparable electrolytics (of the time at least), but the ability to “self-heal”, present in liquid electrolytics, is generally forsaken in solid capacitors as a result.

I attached a catalogue which includes the datasheet for the SA series (found on page 43). It seems the ESR readings are fairly close to those in the datasheet, provided the case sizes match those in the datasheet.

[momaka]

Re: Very old Sanyo OS-CONs. Safe to use?

So what's your short answer then?
Use them? Don't use them? Try them.
I'd say try with caution. Or better yet, first charge to full voltage and check leakage current. If all is well... let's go!

Thanks for sharing that datasheet by the way!

[petehall347]

Re: Very old Sanyo OS-CONs. Safe to use?

use them in your own projects

[Wester547]

Re: Very old Sanyo OS-CONs. Safe to use?

So what's your short answer then?
Use them? Don't use them? Try them.
I'd say try with caution. Or better yet, first charge to full voltage and check leakage current. If all is well... let's go!

Sorry, got carried away and forgot to mention that part. Use them at your own risk (with caution). Although, despite being Japanese made solid capacitors, something makes me uneasy about using said capacitors from three decades ago, even in breadboard projects. Of course, better those than 30 year old Junkcons...

[momaka]

Re: Very old Sanyo OS-CONs. Safe to use?

Of course, better those than any Junkcons...

Corrected that for you.

Well, at least I would gladly use these over GSC / Evercon / Sacon FZ and Rulycon (fake Rubycons, no surprise). Heck, these might be better over a lot of other junk brands like CapXon and Cheng/Chang/ X.

[quicknick]

Re: Very old Sanyo OS-CONs. Safe to use?

Thank you for all the answers (and for the datasheet, the case size is indeed the same). Haven't had the time to play with them, but I'll check back in a few days with some results.

[Topcat]

Re: Very old Sanyo OS-CONs. Safe to use?

Being polymer, and good polymers at that....I would use them without any concern.

[mockingbird]

Re: Very old Sanyo OS-CONs. Safe to use?

I would certainly not use old OS-CON caps. They do in fact deteriorate. Just open it up and see for yourself. The polymer dielectric should be a moist, glossy black but you will often find in old polymers (or junk counterfeit Chinese polymers for that matter) a crusty, often white and scaly layer.

Good polymers will also often exhibit a well defined concentric circle when the innards are removed and the "roll" is looked at from the top.