[sdiy] Tantalums, lytics

[Ingo Debus]

Am 11.06.2009 um 18:51 schrieb Samppa Tolvanen:

>>
>> Not necessarily. I recently had to replace some about 40 years old  
>> lytics
>> that had gone up in capacitance, some of them had become leaky  
>> too. See the
>> thread "How do old electrolytics go bad?" in February.
>>
>
> What might be the reference? The Breaking News - 40 Years old
> wet-electrolytics replaced? You found these -10/+50% caps to be Way
> outta Specs? Quickly browsing the thread, it seems like there was no
> blown caps involved? No collateral damage?
>

No visible damage on the caps, but as I wrote, some were leaky.
A (germanium) transistor died too, perhaps due to a leaky cap.


> YES, as thee electrolytic dries Your DMM starts to tell lies about the
> capacitance values,

That's easy, I just tried it. Measure a known good cap, then put some  
resistors in series. With increasing resistance the reading gets  
lower, not higher.


> but a proper ESR meter will show how resistive the
> load has become or just scoping around the rails for ripple.
>
> NO, somehow You can't do these tests on 40 Years old tantalums. ;)

Perhaps ask again in 10 years or so ;-)

Ingo