Questions capacitors

[cloudff7]

1) Is it a myth or a truth? Is there a difference in the restoration of these aluminum electrolytic capacitors and the time they can be stored without voltage when energizing electronic devices that have aluminum electrolytic capacitors for 30 minutes vs. 1 hour?

2) Example: where I live, the temperature varies between 33-35C and humidity ranges from 57-67%, and I have electronic devices manufactured in the early 90s. Is energizing them every 12 months enough to keep these capacitors in good working order?

[vf1000ride]

I've never heard of the concerns you are thinking of with electrolytic caps.  What I have always been told is that the electrolyte in the capacitor is a liquid or gel and that over time they can leak and the electrolyte will dry out.  I doubt energizing the circuit once a year is going to prevent the dryout process. 

 

I'm actually in the process of changing a couple of electrolytic caps in an old Atari 2600.  It was made in 1980 and has never been recapped so I'll have to wait and see if there is any improvement in the performance of the system.

[cloudff7]

What recommendations on how to prevent deformation of the dielectric layers in aluminum electrolytic capacitors from my collection stored electronic devices that were manufactured in the early 90s and early 2000s and store in my home at a temperature of 33-36C, humidity 57-67% and energized devices at 220v AC 60hz?

[RollyShed]

On 1/10/2025 at 5:10 AM, cloudff7 said:

What recommendations on how to prevent deformation of the dielectric layers in aluminum electrolytic capacitors from my collection stored electronic devices that were manufactured in the early 90s and early 2000s

Between 1999 and 2007 millions of bad capacitors were made -
https://en.wikipedia.org/wiki/Capacitor_plague

 

They are fairly obvious by their bulged tops after a year of use.

 

Otherwise the only way you have of checking them is use your capacitor tester.

Do you have one?
If not why not?

Do you have a DVM?
If not, why not?

[mariushm]

The bottom rubber or plastic on electrolytic capacitors starts to rot and crack after around 20-25 years, so even if you're doing the kind of maintenance you think of, the capacitors will eventually break and electrolyte will start to leak from the bottom.

 

Without any use, the liquid or  semi-liquid electrolyte inside capacitors doesn't react with anything, so very little gas would form and there's no reason for electrolytic capacitors to swell their tops or leak due to internal pressure.

 

You can reform capacitors... that's a thing ... if used then left unused for a long time big capacitors can degrade... but reforming is done by low currents and slowly increasing the voltage on the capacitor ... not by starting a device which would basically "shock" the capacitors with that high voltage.  But ... in theory, powering a device once every 6- 12 months for a few hours would basically reduce the risk of capacitors degrading.

 

 

 

 

[Needfuldoer]

I collect and restore old computer junk from around that era. The biggest cause of leaking surface-mount capacitors from that period is just plain age, not whether they were used or not.

 

If you want to learn more about the science behind electrolytic capacitors, Shelby from Tech Tangents has a pretty accessible rundown:

 

 

In general, you don't have to worry about it except for the giant ones that are the size of soup cans. If caps fail, they fail.