[HAM] Those Pesky Cathode Bypass Capacitors

[Keith H Clark]

Yes.

-----Original Message-----
From: hammond-bounces at zeni.net [mailto:hammond-bounces at zeni.net] On Behalf
Of Scott Hawthorn
Sent: Tuesday, July 22, 2008 2:55 PM
To: The Hammond Forum
Subject: Re: [HAM] Those Pesky Cathode Bypass Capacitors

At 11:43 AM 7/22/2008, Keith H Clark wrote:
>The reason the bypass caps needed replacing was not that their capacitance
>had dropped appreciably but that their ESR or internal series resistance to
>the audio signal had risen enough to affect the sound.Keith

Yup, that's what David said, I read it. And?

All the more reason to just replace them when you're in there. Are you 
telling us that you actually test caps for ESR when you're working on an 
amp?   :-)

>-----Original Message-----
>From: hammond-bounces at zeni.net [mailto:hammond-bounces at zeni.net] On Behalf
>Of Scott Hawthorn
>Sent: Tuesday, July 22, 2008 12:14 PM
>To: The Hammond Forum
>Subject: Re: [HAM] Those Pesky Cathode Bypass Capacitors
>
>At 09:06 AM 7/22/2008, David Anderson wrote:
> >Scott,
> >In your experience with rebuilding/repairing AO-28s, have you found
> >that these bypass capacitors degrade faster or more often than the
> >high voltage supply capacitors?
> >
> >The reason I ask is that in this 1970 preamp, just replacing the
> >bypass caps really made the organ sound great. There is very little
> >power supply ripple on the high voltage capacitors, ~10 millivolts.
> >As I've said myself before, it's good to replace all these as a
> >matter of routine maintenance, but perhaps the lower voltage sections
> >just don't last as long.
> >
> >I'm thinking of doing my next preamp rebuild with all discrete
> >capacitors mounted under the chassis. Sprague/Vishay, Panasonic,
> >Nichicon, CDE, etc... all make electrolytics that measure better than
> >current multi-cans, though the venerable Sprague Atoms have jumped in
> >price of late.
>
>I've never had any way of really knowing what the condition of these caps
>were. We pragmatic-types, when we're on the clock, just replace 'em. In the
>case of electrolytics, an exception is made to "if it ain't broke, don't
>fix it," because in this case, if it ain't broke, it soon will be after all
>these years. Sometimes the amp sounds better afterwards, sometimes, not so
>much. It's an interesting question to which I'm betting you won't find a
>definitive answer here. I do appreciate your thirst for knowledge. I dunno
>much; I just fix 'em!
>
>
>
>
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