I meant to say 450V or more!
Carl
KM1H
----- Original Message -----
From: "Jim Hargrave" <w5ifp@gvtc.com>
To: "Carl" <km1h@jeremy.mv.com>; <amps@contesting.com>
Sent: Thursday, March 29, 2012 9:51 AM
Subject: RE: [Amps] How to know when filter caps begin to fail
> 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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