[Boatanchors] Electrolytic Reforming Time

[J. Forster]

If you have the unit fused right, even if a cap does eventually fail, it
won't take the transformer with it.

-John

===============



> Id tend to flip those percentages to maybe 10-20% and thats with very high
> quality caps and some fairly late ones.
>
> It seems to me that we only hear from the same "reformers" over and over
> and
> the failed ones are very silent while licking their wounds and searching
> for
> new transformers or a rewinder.
>
> Just my $.02
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: "Robert Nickels" <ranickel at comcast.net>
> To: <boatanchors at mailman.qth.net>
> Sent: Saturday, December 31, 2011 4:32 PM
> Subject: Re: [Boatanchors] Electrolytic Reforming Time
>
>
>> On 12/30/2011 11:50 PM, Phil wrote:
>>> So, it doesn't pay to take any chances with those 'lytics.
>> I agree with all that's been said but would just add that this business
>> of "bringing it up slowly on a variac" should be relegated to the urban
>> legends file.  It's better than just applying full AC power, but is
>> still guesswork.   The only way to properly reform an electrolytic -
>> regardless of age - is to limit (and measure) the amount of current
>> being applied to attempt to "reform" the anode oxide layer that was
>> "formed" at the factory when the cap was manufactured.
>>
>> A good description of how the aluminum electrolytic capacitor works can
>> be found here:
>> http://www.elna-america.com/tech_al_principles.php
>>
>> And here's a good reference for how to reform capacitors properly as
>> well as some alternatives:
>> http://www.nmr.mgh.harvard.edu/~reese/electrolytics/
>>
>> I prefer to measure and limit the current to about 5 ma while the oxide
>> layer is reforming; trying to do the job by simply cranking up a variac
>> every so often might work some of the time, but is like tuning your rig
>> while blindfolded.
>>
>> I generally just replace electroyltics that are  cheap and readily
>> available and attempt to reform those that aren't.  I think most
>> "reformers" find the process can restore 80-90% of old caps when done
>> right, without fear of explosions or failure.
>>
>> 73, Bob W9RAN
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>
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