My old Eico model 950 still works great. It goes to 500v and covers most
common electrolytics.
73s de Jim
W5IFP
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]On
> Behalf Of Carl
> Sent: Thursday, March 29, 2012 8:28 AM
> To: Al Kozakiewicz; 'k7fm'; amps@contesting.com
> Subject: Re: [Amps] How to know when filter caps begin to fail
>
>
> Very few have access to a ESR tester that works at 45V or more
> and these
> hand helds are completely useless for this since they use 9V or less.
>
> Mine are a military ZM-11 and a Sprague TO-6A plus a 1940 model
> 16 (Postwar
> renamed the TO-3) that goes to a bit beyond 1000V and that one
> has caught
> several oil filled over the years.
> Nothing lasts forever.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Al Kozakiewicz" <akozak@hourglass.com>
> To: "'k7fm'" <k7fm@teleport.com>; <amps@contesting.com>
> Sent: Wednesday, March 28, 2012 11:42 PM
> Subject: Re: [Amps] How to know when filter caps begin to fail
>
>
> > ESR is a good indicator for end of service life. With an
> ample current
> > source, increased resistance = more power dissipated in the
> component =
> > more heat = more boom. Increasing ESR is usually accompanied
> by decreased
> > capacitance. If you can't measure ESR, an electrolytic significantly
> > below the normal -20% tolerance probably means it's
> approaching the danger
> > zone in addition to losing effectiveness.
> >
> > Although not directly related to the mac daddies used in amplifiers,
> > apparently there has been a major problem with electrolytics
> in general
> > starting the late 1990s, mainly with components labeled as
> manufactured in
> > Taiwan (though counterfeits may be a major contributor). I
> know that I've
> > taught the network techs at work how to salvage a large
> number of dead
> > monitors without a schematic or any diagnostic tool other
> than examining
> > the electrolytic capacitors for bulging. Replacement almost always
> > resurrects the device. There's a wikipedia entry on this
> problem called
> > "capacitor plague" or some such.
> >
> > Al
> > AB2ZY
> >
> > -----Original Message-----
> > From: amps-bounces@contesting.com
> [mailto:amps-bounces@contesting.com] On
> > Behalf Of k7fm
> > Sent: Wednesday, March 28, 2012 11:23 PM
> > To: amps@contesting.com
> > Subject: Re: [Amps] How to know when filter caps begin to fail
> >
> > So, after all the horror stories of exploding caps, I want to
> mention that
> > a few months ago, I removed each original capacitor from one
> of my Alpha
> > 76A amplifiers. It was fairly low time and had been sitting
> on the shelf.
> > I reformed each capacitor, measured the capacitance, and they
> were all
> > within factory specs. I then formed each one, working up to
> 450 volts,
> > the rated voltage. Each one had very low leakage. ESR on
> each one tested
> > as good as new. So, I put them back into the Alpha. I was
> also surprised
> > that the original carbon composition resistors were each
> within tolerance
> > and quite close to each other.
> >
> > I could have installed new capacitors, but after passing all
> these tests,
> > I did not hesitate to reinstall them into the amplifier.
> Heat contributes
> > greatly to the aging process.
> >
> > Unless I was comfortable with the results of these tests, I
> would have
> > replaced them. I own and fly an old wood aircraft. Things
> get replaced
> > if they need replacing - but if they are still good, they do not get
> > replaced.
> >
> > 73, Colin K7FM
> >
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> >
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>
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