[Amps] How to know when filter caps begin to fail

Thu Mar 29 09:57:54 PDT 2012

I have a Sprauge TO-5, TO-6A and a Eico 950B.  They are my buddies when it comes to caps.  The Eico is a real sleeper at the hamfests.  I have seen them go for as little as a dollar or two at times, but you have to be an early bird!
The eye tube is worth that!  As Jim pointed out it can go to 500 V.  The 950B also provides a ESR "power factor" reading.

The 950B manual is here:
http://www.nostalgiaair.org/References/Manuals/EIC/EIC_13.zip

For as little as they cost there is not reason not to have one.

Randy AB9GO

Randy E. Randall AB9GO
Network Engineer
UC Health
Randy.Randall at UCHealth.com
Phone 513-585-7146
Fax 513-585-7159

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On Behalf Of Jim Hargrave
Sent: Thursday, March 29, 2012 9:52 AM
To: Carl; amps at contesting.com
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 at contesting.com [mailto:amps-bounces at contesting.com]On
  > Behalf Of Carl
  > Sent: Thursday, March 29, 2012 8:28 AM
  > To: Al Kozakiewicz; 'k7fm'; amps at 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 at hourglass.com>
  > To: "'k7fm'" <k7fm at teleport.com>; <amps at 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 at contesting.com
  > [mailto:amps-bounces at contesting.com] On
  > > Behalf Of k7fm
  > > Sent: Wednesday, March 28, 2012 11:23 PM
  > > To: amps at 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
  > >
  > > _______________________________________________
  > > Amps mailing list
  > > Amps at contesting.com
  > > http://lists.contesting.com/mailman/listinfo/amps
  > > _______________________________________________
  > > Amps mailing list
  > > Amps at contesting.com
  > > http://lists.contesting.com/mailman/listinfo/amps
  > >
  > >
  > > -----
  > > No virus found in this message.
  > > Checked by AVG - www.avg.com
  > > Version: 10.0.1424 / Virus Database: 2113/4900 - Release
  > Date: 03/28/12
  > >
  >
  > _______________________________________________
  > Amps mailing list
  > Amps at contesting.com
  > http://lists.contesting.com/mailman/listinfo/amps

_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps

Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information.  Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.