SB220 Filter Caps

[Glen Zook]

They certainly were not that well matched when new!
Most of the older electrolytic capacitors had a
tolerance of -50% / + 80%.  Newer ones have a +/- 20%
tolerance.  Also, the equalization resistors that
should be across the capacitors take care of any
problems.

Mouser has 220 mfd @450 volt capacitors for $7.21 in
single quantities or $6.01 each in quantities of 10.
You might as well get 10 and have 2 additional
capacitors for $2.32 more.

The Mouser part number is 5985-85-450V220

These are physically much smaller than the originals
(due to more "modern" construction techniques).

The original capacitors could each have a value of as
low as 100 mfd and as high as 360 mfd.  The newer ones
can have a low value of 176 mfd or as high as 264 mfd.
 This is much closer to the nominal value of 200 mfd
of the originals than what the tolerances of the
originals allow.

You should be able to reuse the existing resistors.
If not, suitable resistors can also be obtained from
Mouser at a very low cost.  1N4007 diodes can be had
from them as well at $2.70 for a quantity of 100.

You can get Mouser on the Internet at mouser.com and
can order directly using a credit card.  There is no
minimum order from US addresses.

Glen, K9STH



--- John C Owens <jcowens3 at JUNO.COM> wrote:

Has anyone replaced the electrolytic filter capacitors
(8 ea, 200uF, 450V) on an SB220 or SB221. If so, I
would be interested in knowing the source you used for
buying the replacement caps, etc. I am aware of the
Harbach Electronics replacement filter capacitor bank,
complete with bleeder risistors and protection diodes
that is available for around $125. Given the need for
these to be fairly closely matched, has anyone worked
the problem with a successful conclusion??


=====
Glen, K9STH

Web sites

http://home.attbi.com/~k9sth
http://home.attbi.com/~zcomco

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