No need to reform, they are brand new Elna Silmic II
sounds good now, but I expect even better results as I'm still far from the 100hours break-in recommanded for those caps.
All electrolytics (except maybe the obsolete Blackgates) need to be reformed if more than a few days have expired since the last reform.
The electrolytic manufacturers state the maximum time as 24hours to require a reform before testing.
The electrolytic manufacturers state the maximum time as 24hours to require a reform before testing.
I've not heard of anybody reforming brand new capacitors prior to install them... you're the first speaking about it!
Slowly charge them.
They leak, sometimes badly.
I typically limit the charging current <10uA
and then keep the charge there for 24hrs, followed by a slow discharge using maybe 10k and then a further slow charge for another 24hrs.
This gets the leakage down VERY low.
They leak, sometimes badly.
I typically limit the charging current <10uA
and then keep the charge there for 24hrs, followed by a slow discharge using maybe 10k and then a further slow charge for another 24hrs.
This gets the leakage down VERY low.
I use a dvm ohms scale to charge them up to 2v. Not all that foll-der-all. Low ohms first then higher & higher ohms scale to see if they leak or not. New ones should go overload on ohmsx200000 scale.
This starts the insulating chemistry working again.
I buy "expired" caps (past shelf life) from Newark for a discount, and they sit past shelf life anyway in my bins, so a leak test/charge up is useful. Of the hundreds I've put in these old organs since 2008, I've never blown one that wasn't backwards. They should charge to battery voltage anyway, and you can get a feeling for the quality by switching to 2 v scale and watching the voltage self discharge. Fast=bad, slow=good. Different sizes have different self discharge rates. A useful test also for old used caps (although doesn't say how age cracked the elastomer seal is)
E-cap shelf life is surprisingly short. Read the datasheet. A useful number for people running pick&place machines, not so useful for home hobbiests. At home, it is going to be expired if it has been in the bin. Most other vendors don't discount their old stock like farnell does.
This starts the insulating chemistry working again.
I buy "expired" caps (past shelf life) from Newark for a discount, and they sit past shelf life anyway in my bins, so a leak test/charge up is useful. Of the hundreds I've put in these old organs since 2008, I've never blown one that wasn't backwards. They should charge to battery voltage anyway, and you can get a feeling for the quality by switching to 2 v scale and watching the voltage self discharge. Fast=bad, slow=good. Different sizes have different self discharge rates. A useful test also for old used caps (although doesn't say how age cracked the elastomer seal is)
E-cap shelf life is surprisingly short. Read the datasheet. A useful number for people running pick&place machines, not so useful for home hobbiests. At home, it is going to be expired if it has been in the bin. Most other vendors don't discount their old stock like farnell does.
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I am troubled by your posts on this, Andrew. I do understand the principles of so-called reforming the wet cap.
I am old enough to have started my interest in audio just before solid state appeared. We certainly used to hook up high voltage (B+) caps through a resistor to the supply and let them charge for a while - especially if they were "unknowns" out of the junk box!
However, since then, in over 40 years of design, production and field service / repair of LF/MF electronics, mostly analog and digital instrumentation I have never experienced ANYONE, including myself having any fears or concern about reforming Elcos!
New parts that have sat in stores for years, test equipment (with mains PSUs of course) that have been unused for years, or replacing a dead one with something straight out of the Digikey bag (did they reform before shipment?)
I don't doubt that this may appear in some datasheets. I can imagine the rationale for big beefy reservoir caps. But for every elco in the system including tiny 2.2uF coupling caps? I don't think so!
I am old enough to have started my interest in audio just before solid state appeared. We certainly used to hook up high voltage (B+) caps through a resistor to the supply and let them charge for a while - especially if they were "unknowns" out of the junk box!
However, since then, in over 40 years of design, production and field service / repair of LF/MF electronics, mostly analog and digital instrumentation I have never experienced ANYONE, including myself having any fears or concern about reforming Elcos!
New parts that have sat in stores for years, test equipment (with mains PSUs of course) that have been unused for years, or replacing a dead one with something straight out of the Digikey bag (did they reform before shipment?)
I don't doubt that this may appear in some datasheets. I can imagine the rationale for big beefy reservoir caps. But for every elco in the system including tiny 2.2uF coupling caps? I don't think so!
It's funny that when I test electrolytic capacitors, it sort of mimics what Andrew says.
Almost everything I buy is in lots of at least ten, so parts sit around for months or even years before being used.
For electrolytics, I do a basic leakage test with an ohm meter. You can see the capacitor charging up in the display reading; the resistance will go up to "infinity" if the capacitor doesn't leak. Then I immediately check the charged voltage. I let the capacitor sit for 24-48 hours and recheck the voltage; a leaky capacitor will already be discharged. Then if the capacitor is good, I observe the discharge voltage; the range on the ohmmeter affects the discharge rate. Then if it passes all tests, I use it.
I know that capacitors need to be "reformed" after sitting, so the procedure accomplishes two things at once.
Almost everything I buy is in lots of at least ten, so parts sit around for months or even years before being used.
For electrolytics, I do a basic leakage test with an ohm meter. You can see the capacitor charging up in the display reading; the resistance will go up to "infinity" if the capacitor doesn't leak. Then I immediately check the charged voltage. I let the capacitor sit for 24-48 hours and recheck the voltage; a leaky capacitor will already be discharged. Then if the capacitor is good, I observe the discharge voltage; the range on the ohmmeter affects the discharge rate. Then if it passes all tests, I use it.
I know that capacitors need to be "reformed" after sitting, so the procedure accomplishes two things at once.
"I can see your logic:
If it didn't blow up, then it must be OK."
I cannot read your sentiment from that. typical dour Scot! 😀
The point was that it was not logic. Reforming was never on the radar for me or anyone else I was involved with.
Do you really think that high speed (or any speed!) production lines reform elcos on the bandoleer BEFORE stuffing the pcbs?
If it didn't blow up, then it must be OK."
I cannot read your sentiment from that. typical dour Scot! 😀
The point was that it was not logic. Reforming was never on the radar for me or anyone else I was involved with.
Do you really think that high speed (or any speed!) production lines reform elcos on the bandoleer BEFORE stuffing the pcbs?
Where do they do that? Perhaps you have a link?
I have just briefly searched RS for a variety of cap values' data sheets. I cannot see any reference to this, nor even the word "reform" in any of them.
i do reform big computer grade caps that have been on the shelf for a long time...
and then after reforming, short the terminals to keep them from again accumulating charge...
however, for small caps in boards, i never bothered, they will sort themselves out with use,
what with such impedances associated with them anyway...
so i am eager to see whatever documentation Andrewt might have....
and then after reforming, short the terminals to keep them from again accumulating charge...
however, for small caps in boards, i never bothered, they will sort themselves out with use,
what with such impedances associated with them anyway...
so i am eager to see whatever documentation Andrewt might have....
I seem to recall an electrolytic data sheet saying that reforming may be needed if the cap has been unused for more than a couple of years since manufacture. It may also be needed before formal testing i.e. the cap might not meet its leakage spec but will work fine in a circuit because the circuit will reform it when switched on.
Don't know of anyone who does this in the real world of electronics, I have always been told a few microseconds with a voltage on them in circuit does the trick... Bit suspect of this!
The manufacturer tells us that the leakage should be below a specified level within 2 minutes (or some other minutes) of applying the voltage.
That tells me and you that microseconds does not do the trick.
That tells me and you that microseconds does not do the trick.
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