How to measure the aging of electrolytic caps

[jensenmann]

HI everybody
Is there a way to measure the aging process of ´lytics.
When they dry out their capacitance will decrease, that´s clear. But how fast will this happen and how can I decide if it´s too old (besides looking at the actual cap value compared to the original value)?

The background is that I have a load of old gear lying around and recapping it would cost me a fortune. So I´m trying to find a way to figure out if a particular ´lytic needs to be replaced or can be left.

:sam:
Jens

 

[NewYorkDave]

An ESR meter.

 

[jensenmann]

Dave, thank you for your fast answer.

http://clientes.netvisao.pt/greenpal/evb1.htm
has a good reading about this subject in the downloadable manual.

And another good reading:
http://www.siliconchip.com.au/cms/A_100895/article.html

:green:
:thumb: :thumb: :thumb:
Jens

 

[NewYorkDave]

the "old classic" is the Creative Electronics ESR meter. We use one at my job. There used to be a website about this meter, but it's down now. However, an archive of the site can be found here. Grab it while you can.

 

[Milkmansound]

http://www.anatekcorp.com/testequipment/esrcompar.htm

I use the Dick Smith meter - its fairly cheap as a kit, and it has saved me many many hours repairing televisions and stereos, since they use the cheapest caps in the world and they suffer from high ESR almost right out of the factory.

 

[smallbutfine]

If you have a scope you could try this:
http://www.fullnet.com/u/tomg/esrscope.htm

didn't try myself as i don't have a scope for now...

but maybe i will try this one, looks cheap and fun:
http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
or even better, because this one has a scale :grin: :
http://ludens.cl/Electron/esr/esr.html

 

[CJ]

Put them under heated knobs to reform them. :razz:

 

[smallbutfine]

ehem...WHAT do you do, CJ? What kind of knobs? what heat, how long??? :shock:

 

[maxwall]

Well , Im not so impressed with ESR meters

I have a capacitor wizard ESR meter thinking it would find bad caps but don't be fooled , this meter is not as accurate as you may think.

I was trouble shooting a filter capacitor in a friends ampeg bass amp and the filter cap would short and spark and pop momentarily when turned on.
It would be clear that the insulator material was failing in the cap. Well I measured it with the ESR meter and it told me the cap was good - bulls#@t !!

I replaced the cap and the sparking poping and shorting is gone. So how did the meter help me - it did'nt.

And to be completely honest, I have'nt found a bad cap yet with this junk meter. buyers beware, the meter was $150

 

[NewYorkDave]

Well, the meter obviously couldn't provide the high polarizing voltage that was punching through the dielectric, and was therefore "fooled." But I wouldn't go so far as to say that ESR meters are useless. Our old Creative Labs meter has proven very handy--but no piece of test equipment is 100% foolproof 100% of the time. I have no experience with the "capacitor wizard."

What would have helped, in your case, is one of those old-fashioned "capacitor testers" like Eico used to make, that provide a variable polarizing voltage that can go pretty high, if I recall correctly.

 

[Gus]

A sencore 102 will check leakage at up to 999VDC. Some caps have problems at higher voltage.

maxwall the problem you had would not show on almost any ESR meter. The caps had high leakage at a voltage that it broke down at.