[Boatanchors] Electrolytic Reforming Time

[Al Klase]

I'm with Carl on this one.  I'd started to go easy on replacing 
electrolytics, as a lot of the post-war ones seemed to come around and 
function OK.

THEN, a Sprague twist-prong that had been working happily for two weeks 
exploded.  There was a bunch of shredded material on the PS, but the can 
was not in evidence.  A little looking around found it across the great 
room, and a little more looking revealed a 3/4" deep dent 16 feet up on 
the cathedral ceiling,

'nuff said!

Al

On 12/30/2011 9:20 PM, Geoff wrote:
> Just replace all electrolytics as dried out electrolytes will not magically
> repair themselves.
> Reforming is pure folly as a complete failure will happen but you cant
> predict it.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "J. Forster"<jfor at quikus.com>
> To: "W8KZW"<w8kzw at arrl.net>
> Cc:<boatanchors at mailman.qth.net>
> Sent: Friday, December 30, 2011 5:36 PM
> Subject: Re: [Boatanchors] Electrolytic Reforming Time
>
>
>> I increase the voltage slowly monitoring the reforming current. You should
>> keep the current low to (a) Limit local damage w/in the cap (b) prevent
>> the whole cap from overheating, and (c) allow fluids to redistribute.
>>
>> For an old capacitor several days is not unreasonable.
>>
>> -John
>>
>> ===============
>>
>>
>>> I just exchanged emails with a ham intending to spend up to two weeks
>>> bring
>>> a Heathkit Sixer up on a Variac.  Seems excessive to me.
>>>
>>> I generally bump the Variac 10 volts per hour, starting at about 60 volts
>>> so
>>> the rectifier generates B+.  Haven't had any issues that I can tell.
>>>
>>> When I put an old electrolytic on my Sprague TO-5 and bring it up to full
>>> voltage, it only takes a few minutes for the current to drop to a
>>> near-zero
>>> level (on a good cap, anyway).  I figure that's when the can is reformed,
>>> and anything beyond that is wasted - but I go an hour at each level on
>>> the
>>> rig I'm bringing back just for some added margin.
>>>
>>> I'm certain opinions about this will range across the board, but I wonder
>>> if
>>> anyone has any feedback based on documented studies?
>>>
>>> 73,
>>> Jeff
>>> W8KZW
>>>
>>>
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>>
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/