New-old stock capacitors

[Tioleco]

You can use new-old stock electrolytic capacitors, but with 5 or more years old?
They can deteriorate even without use during this period?
There are some selling on ebay for a good price and I do not know if it's worth.

[digge]

Re: New-old stock capacitors

I would be very careful about anything bought on ebay. The item being old might not be the only problem. As many posts here can testify there are few sellers that actually sell genuine parts at all. And even if they are genuine parts 5 years can mean that you basically bought something that doesnt work using for anything. Depends quite a bit on how they have been stored and stuff as well.

So imo, dont buy them.

[ipman]

Re: New-old stock capacitors

I have many old caps, one of them dating before 90's which are ok. They were not used, just sat in a box.
But also had several ones damaged also sitting.
You may never know.

[riotpack]

Re: New-old stock capacitors

With the new price of most not being high, unless they were of an extreme voltage or had a high value of capacitance then I wouldn't bother. A reforming would be a good idea but buying them would be a bad idea unless as I said, they are of an expensive make up in Voltage/Capacitance.

[jeffescortlx]

Re: New-old stock capacitors

Back in my day, cap's would last 30+ years. Used or not.

[PCBONEZ]

Re: New-old stock capacitors

Technically you should "reform" them and they are fine but I've never had any issues with caps up to 10 years old without reforming.
I don't think it's realistically much of a problem at 12v or less actual voltage as on a mobo.
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Reforming is just applying DC voltage [through a current limiting resistor] starting with a low voltage [like 1-2 volts] and slowly bringing it up to rated voltage at a rate of something like a volt every 5 minutes. Once at rated volts leave it there for about a minute per month of age.
[The manufacturers state different procedures and those numbers are ball-park/typical and would work fine.]
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Reason is as they sit on the shelf the oxide layer [dielectric] on the foil slowly dissolves into the electrolyte making the layer thin. When you put voltage to it the thinned layer can allow excessive leakage current creating localized shorts in the cap which won't heal. Applying DC voltage gradually causes the oxide layer to rebuild to it's original thickness and the caps is essentially as good as new. [Lytics used to commonly be called 'self healing caps' because, unless it's excessive, damage to the oxide layer fixes itself.]
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[kc8adu]

Re: New-old stock capacitors

i have used many caps over 5 years old.never a problem.hv ones get reformed though.they seem to suffer the worst from long storage.got a drake l4b on the variac now to reform caps.

[lti]

Re: New-old stock capacitors

The caps I used in my Sony boombox were manufactured in 1993 or 1997 (I don't remember the exact year) and had never been used until then. They tested good directly out of the bags.

[Agent24]

Re: New-old stock capacitors

Silicon Chip recently did a project on a capacitor reformer\tester

http://www.siliconchip.com.au/cms/A_112073/article.html

Probably overkill for most, though.

[Longbow]

Re: New-old stock capacitors

There are lots of NOS excellent quality electrolytics out there. The bargains are usually axial lead high voltage or high value capacitors that were used in tube gear or computer power supplies. Obviously there is no point in reviving a stack of 10 uF 25 volt general purpose caps. Pick a great brand such as Sprague. All you need is a variable d.c. supply, and some resistors. Apply low voltage through a limiting resistor while monitoring the voltage across the capacitor. After 15 minutes or so, increase the voltage a little and repeat until you get near the working voltage of the cap. Later, you can measure discharge time through a high value resistor to confirm, or see how long a charge is retained with no load to check leakage.