[Boatanchors] Reforming Electrolytic Capacitors

[Nick England]

Uh Oh, it's a linear - This has like multiple 450v caps in series, doesn't
it?
So if one cap isn't reforming you may not know it until it explodes from
over-current, while the others in the stack explode from over-voltage,
unless your HV xfmr secondary opens up first....

Given the value of a NOS amp, I'd open it up and use some clip leads to
reform each cap individually using a separate 450v supply while monitoring
the reforming current.

Nick England K4NYW
www.navy-radio.com

On Mon, Feb 20, 2017 at 5:00 PM, D C _Mac_ Macdonald <k2gkk at hotmail.com>
wrote:

> I can't really do that.  The interlocks ensure that I can't even turn the
> amp on unless the case is installed and bolted down.
>
> 73 de Mac, K2GKK/5 in OKC
> ________________________________
> From: Ron <ronami at yahoo.com>
> Sent: Monday, February 20, 2017 15:55
> To: D C _Mac_ Macdonald; boatanchors at mailman.qth.net; Drake Mailing List
> Subject: Re: [Boatanchors] Reforming Electrolytic Capacitors
>
>
> In principle, increase to the next step when the current into the cap is
> less
> then the rated leakage current. When the latter is not known, select a
> 'safe'
> value. Say, 1mA.
>
> -- Ron
>
>
> ________________________________
> From: D C _Mac_ Macdonald <k2gkk at hotmail.com>
> To: "boatanchors at mailman.qth.net" <boatanchors at mailman.qth.net>; Drake
> Mailing List <drake at mailman.qth.net>
> Sent: Monday, February 20, 2017 4:37 PM
> Subject: [Boatanchors] Reforming Electrolytic Capacitors
>
> The Drake L-75 Linear Amplifier I am trying to safely bring back to life
> left Drake's build line on May 14, 1981.
>
> It has NEVER had high voltage applied to the filter network.  The plate
> transformer was still in its sealed shipping carton so had never been
> installed.
>
>
> Who has any recommendations for "reforming" the filter caps?  I have it
> set up on a Powerstat (like Variac)
>
> and can bring the plate supply up gradually.  At first, I am applying 10
> to 120 VAC to the 240 VAC input to the power transformer.  I can rewire as
> appropriate to bring it to 240-250 VAC input.
>
>
> Using 10 Volt steps, what do you recommend for duration at each 10 Volt
> interval?
>
>
> 73 de Mac, K2GKK/5
>
> Oklahoma City, OK
>
>
>
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