[Boatanchors] Capacitor Reforming

[Bonddaleena at aol.com]

In a message dated 2/13/2006 1:51:58 PM Eastern  Standard Time, 
kulow at epix.net writes:
<snip>
> Here is a common  scenario, I’m at 50V and leakage 
> current is 2mA, I increase to 100V and  leakage
goes to 
> 10-12mA then gradually over the next minute  drops
back to 
> 2mA. Am I watching the reforming process  take
place? Am I 
> “pushing” the process too fast? All input  welcome.
> 
> Dave, WW8S

I have a Sprague TO-6 and the manual  is quite
helpful on 
this topic.  I think BAMA has it for  download.  Well
worth 
the download time.

Anyway, according to  the manual, when reforming a
'lytic, 
keep the current down below 10 mA to  prevent
overheating.
The table of acceptable leakage shows that a  /new/
80 mF, 
450 WVDC 'lytic should have a maximum leakage
current of  
3.5 mA.  Leakage goes up with age.  To quote,
"Capacitors  
with a leakage current of more than 15 mA should
almost 
always be  discarded."

Depending on how old the 'lytic is, it could take an
hour  
or more to fully reform.  Be patient!

73
Bob WA2UEH

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One of my criteria on old caps is: does it get warm? If so, pitch it.
As you are probably aware, New Old Stock (real, original) electrolytics are  
nfg for replacement purposes. To be sure, I almost always, cut the old cap 
apart  and restuff it with modern replacements. Caps sitting (unused) on a shelf, 
do  NOT age well.....
 
 
ron
 
N4UE