[NJARC] Bring it up slow on the VARIAC

[David Sica]

Jim,

I have, I admit, occasionally (mostly years ago) "plugged it in to see if
it works."  And yes, occasionally, it worked.  I have (again, last time was
years ago) brought it up slowly.  And yes, sometimes that worked too, but I
suspect they might have worked anyway if I had merely plugged them in.

Smarter people than me have since advised me that the only way to do this
intelligently is to bring up the B+ under controlled circumstances with a
lab power supply while monitoring current through the filter cap.  As you
know better than I do, there are leakage parameters to stay within while
raising the voltage.  At some point it becomes a pass/fail situation,
backed by data instead of misplaced hope in aged, deteriorated parts.

So even though it occasionally "worked" I no longer have faith in the
'bring it up slowly on a Variac' method.  And for the modest price of a
couple of replacement electrolytic caps, I no longer bother to make the
meticulous, controlled/measured test.  And I (usually) no longer do the
'cross my fingers and hope that it won't blow up' thing either.

-- Dave



New Jersey Antique Radio Club

On Mon, Nov 7, 2016 at 10:51 AM, <antqradio at sbcglobal.net> wrote:

> Just remember
> Reply = Poster
> Reply All = Everyone
>
> _________________________________________________________
>
> One sees this mentioned all the time in articles on repairing radios.  I
> for one think it is dangerous to expect an electrolytic capacitor to
> properly reform since the reforming current is not controlled or monitored.
>
> Has anyone done this and not had to replace the filter capacitors?
> Jim
>
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