[HAM] CV Preamp rebuild

[David Anderson]

Andy,

The closest contemporary value to .5uf is .47uf, which is probably close enough. If you really wanted to get precise about it, you could parallel a .03uF capacitor to make .5uF, but if you test a few .47uF capacitors, you may find some that measure .49 or so. It's not that big a deal. A 400V rating will do, and a polypropylene dielectric is probably the best. If you use SBE Orange Drops, go for the 716P version over the 715P.

I've never worked on a CV preamp, so I don't know how to advise you to attach it. The one question I would ask is: do you know it's bad or needs replacing? I ask only because some of the metal encapsulated capacitors have proven quite reliable. I know Donald Resor will jump all over me and call me an idiot, but some of those old hermetically sealed capacitors still work fine since the oil they are filled with protects the dielectric and prevents corrosion of the plates and lead connections. If it's wax-dipped, replace it, of course.

David Anderson (preparing for Resor's onslaught of criticism)

-----Original Message-----
>From: Andrew Young <andrew at emailmv.com>
>Sent: Jan 17, 2007 11:04 AM
>To: The Hammond Forum <hammond at zeni.net>
>Subject: [HAM] CV Preamp rebuild
>
>Hi all.
>
>I'm rebuilding my CV preamp (finally).  Everythings gone well so far.  I 
>just have a quick question about the capacitor C6 which is a  .5 400v 
>cap mounted to the outside of the chassis.
>
>1) What is a good replacement value?
>2) how to mount the new cap.
>
>It will be nice to finally have this again.  The amp volume was very 
>minimal.
>
>Thanks.
>
>Andy