Date: Thu, 24 Nov 2011 09:17:14 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: [Amps] best deal for Mallory caps?
On 11/23/2011 12:53 PM, Pete Soper wrote:
> I need several replacement caps for my Ten-Tec Titan 725, Mallory
> CGS401T450R5L (long/slim 400mf 450vdc/85c). Newark wants $29 each. Is
> there a better deal available?
Another important point. It's rare for all of the caps in the series
string to fail. Only one gone bad will cause lots of hum. I use my
trusty Simpson 260 on the middle Ohms range to read charge and discharge
current as I reverse the leads, and compare each cap to the others. A
bad one will have a lot less charge and discharge current. I have three
Titans, so I've been through this several times. Only once when I've
replaced one has another one come up bad in the string.
73, Jim K9YC
## I use my B+K 875-B LCR meter to test hv lytics. The 875-B and other
similar meter's will read as high as 20,000 uf. It will also read D factor..and
that feature alone will find a bad cap instantly. The 875B reads AC
resistance and not dc
resistance..and down to .001 ohm. With this last feature, you can measure the
ESR of each cap
as well. After going through case loads of new caps, they will typ all read
the same esr,
within 1 milliohm of each other, at least for a quality brand of hv cap.
## That 875-B is worth it's weight in gold. #1 amp tool in the shop. Being
able to read down to
.1uh and .1 pf saves a lot of time and effort when either winding coils or
measuring coils, or
measuring caps, and stuff like stray C, tube C, effects of AL side walls,
partitions, etc.
The latest B version I have will also allow to zero out the test leads when on
the uh mode, or
resistance mode..and ditto with C mode.
## for testing HV lytics, the caps have to be discharged 1st of course.
Depending on brand,some
hv caps are way on the high side, and some brands are way on the low side. I
also have the older
B+K 875-A. They come with a 3 year warranty, industry standard piece of
test gear. They are
cheap at Mouser.
Later.... Jim VE7RF
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