I have stored here electronic devices with aluminum electrolytic capacitors used and manufactured in the early 90s. Here the temperature varies between 33-35C. These electronic devices need to be energized what time and frequency to prevent failures in these aluminum electrolytic capacitors caused by disuse?
Aluminum electrolytic capacitor
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Stickman393
Well-known member
Old electrolytics can be re-conditioned. My understanding is that this is done slowly, under controlled conditions. Never got the chance to do it myself.
How long? Dunno. I'm sure there's resources out there.
Here ya go:
hackaday.com
How long? Dunno. I'm sure there's resources out there.
Here ya go:
Electrolytic Capacitor Repair
If you’ve ever worked on old gear, you probably know that electrolytic capacitors are prone to failure. [Dexter] undertook a repair of some four-decade-old capacitors in a power supply. He di…
hackaday.com
Nostradoomus
Well-known member
sounds like it'd be easier to just buy new caps, there's plenty quality ones available
Cybercow
Well-known member
TBH, I had no idea that reconditioning old electrolytics was a thing. Interesting concept.
"The process of reforming an old aluminum electrolytic capacitor consists of the application of rated voltage, through a resistor, for a period equal to five minutes plus one minute per month of storage. The electrolytics appearing on the surplus market have often been in storage for a very long period indeed.
Reforming means to regenerate the oxide layer. This is done by increasing the voltage until current begins to flow. This is not a normal condition for a capacitor. The trick is not to run too much current through it."
"The process of reforming an old aluminum electrolytic capacitor consists of the application of rated voltage, through a resistor, for a period equal to five minutes plus one minute per month of storage. The electrolytics appearing on the surplus market have often been in storage for a very long period indeed.
Reforming means to regenerate the oxide layer. This is done by increasing the voltage until current begins to flow. This is not a normal condition for a capacitor. The trick is not to run too much current through it."
I don't trust "reforming" personally.
Once the electrolyte is degraded, dried up, you're working on borrowed time. There's some validity to bringing something like an old tube amp up to voltage slowly with a variac. Bur I wouldn't trust reforming as any kind of long term solution. It's a short term fix to help you get to the long term solution.
Once the electrolyte is degraded, dried up, you're working on borrowed time. There's some validity to bringing something like an old tube amp up to voltage slowly with a variac. Bur I wouldn't trust reforming as any kind of long term solution. It's a short term fix to help you get to the long term solution.
Stickman393
Well-known member
Honestly, I get the impulse to just toss em.
The way I see it, though, as long as the electrolyte hasn't seeped out, you're good to give re-conditioning a shot.
This is especially pertinent to different applications, though. Variable Frequency Drives (devices that control AC motor speed and torque by rectifying AC mains and then re-assemble an AC sine wave at a lower frequency using pulses of DC at differing amplitudes) can use *very* large electrolytic caps. If one of those sits in storage for some time, re-forming the caps is absolutely worthwhile.
I imagine that this is particularly helpful in situations when dealing with vintage amps too. Old, original spec caps that still work well in a vintage amp could easily make a dumb collector with more money than sense dig deeper into their wallets.
But big, expensive caps are regardless going to be the primary use case for re-forming. I've got some in an unregulated DC power supply that I built from 500VA transformer that cost like 35 bucks a pop. They get pricy.
The way I see it, though, as long as the electrolyte hasn't seeped out, you're good to give re-conditioning a shot.
This is especially pertinent to different applications, though. Variable Frequency Drives (devices that control AC motor speed and torque by rectifying AC mains and then re-assemble an AC sine wave at a lower frequency using pulses of DC at differing amplitudes) can use *very* large electrolytic caps. If one of those sits in storage for some time, re-forming the caps is absolutely worthwhile.
I imagine that this is particularly helpful in situations when dealing with vintage amps too. Old, original spec caps that still work well in a vintage amp could easily make a dumb collector with more money than sense dig deeper into their wallets.
But big, expensive caps are regardless going to be the primary use case for re-forming. I've got some in an unregulated DC power supply that I built from 500VA transformer that cost like 35 bucks a pop. They get pricy.
