Doubt changes with age aluminum electrolytic capacitor

[jobas77]

A used aluminum electrolytic capacitor manufactured in the early 90s and mounted on a PCB. Is the dielectric, electrolytic and chemical composition altered by age and use compared to a new aluminum electrolytic capacitor manufactured recently?

If there is this difference between them, then can't the capacitor from the 90s follow the rule of recommendation to energize the aluminum electrolytic capacitor before 2 years of storage? Is the rule only for new capacitors?

 

[Philbo King]

If you're looking for something to worry about, go ahead and energize them from time to time.

I suppose the caps won't mind either way.

 

[DVDdoug]

If there is this difference between them

Other than non-polarized electrolytics used in speaker crossovers, electrolytic capacitors are rarely used in circuits where the capacitance value is critical. (Better crossovers avoid electrolytics.)

Most capacitors used in audio circuits are less than 1uF so other types of capacitors can be used (without unreasonable cost) and electrolytics usually have 10-20% tolerance so they are usually avoided wherever capacitance value is critical. A larger than "necessary" value is often chosen and in most audio circuits, the capacitance could probably fall to half of its original value with no ill effects.

If the filter capacitors in a power supply deteriorate badly enough you might get hum.

In practice, they seem to last a long time. I did have some small electrolytic capacitors in DIY amplifier EXPLODE when I turned it on after some time. From what I remember, they were being used close to (or at) their voltage rating and when I replaced them I used caps rated for higher voltage. Hmmm... Again, that amplifier has been in the closet for many years...

 

[mhardy6647]

check the capacitance (ideally at or near working voltage) and the ESR. If both are OK, the capacitor is (capacitors are) probably pretty OK (as an erstwhile colleague of mine was wont to say).

Now... 60 or 70 (or more) year old HV electrolytics are a bit more suspect but 1) aren't always bad and 2) can sometimes be reformed (by slowly ramping up applied voltage, e.g., with a Variac). That said, modern electrolytics are intrinsically a bit better than were their ancestors. Smaller, too!

 

[jobas77]

All my aluminum electrolytic capacitors are in stored electronic devices, CRT TVs, SNES, PS2 video games, 5v or 12v power supplies. It is very complicated to remove all capacitors of them to test each individual capacitor.

The manufacturers of aluminum electrolytic capacitors recommend energizing them before 2 years, but is this recommendation only for new capacitors with little use? For used capacitors from the 90s and 2000s, this rule is not useful because they are old and used and the chemistry has changed?

 

[mhardy6647]

ESR can be tested in circuit, and is often the more important variable in aged electrolytics.
What problem or deficiency are you trying to solve by (as they would say on audiokarma.org) "recapping" en masse?

 

[jobas77]

I have no problems with the devices, they work fine and I have not opened my electronic devices. I would like to store them correctly and I know that the main component that suffers in the long-term storage of devices is the electrolytic capacitor.

 

[MaxwellsEq]

What is the problem you are seeking to solve?

If your concern is that you have legacy gear and it will age, that's certainly the case. How serious it will be depends on the age, design etc. If you're unwilling to desolder, measure, reform if necessary and then resolder, then perhaps a strategy of powering everything up every few months may minimise risk.

 

[jobas77]

Is it necessary to energize these devices once a month? What is the maximum safe number of months?