[TenTec] Orion II A9 Board Failure...Again!

[Dr. Gerald N. Johnson]

On Wed, 2008-06-25 at 10:36 -0700, Ron Castro wrote:
> Whoops... that last link was:
> 
> http://n6ie.com/A9_Fix.html
> 
>          Ron  N6IE
>       www.N6IE.com
> 
> 
> ----- Original Message ----- 
> From: "Ron Castro" <ronc at sonic.net>
> To: "Ten Tec List" <tentec at contesting.com>
> Sent: Wednesday, June 25, 2008 10:35 AM
> Subject: [TenTec] Orion II A9 Board Failure...Again!
> 
> 
> > Hank:  Excellent analysis!  Can I please link to that from my page?
> >
> > I believe, based on this link that there is a direct connection between 
> > ESR
> > and ripple ratings:
> >
> > http://wiki.xtronics.com/index.php/Capacitors_and_ESR
> >
> > "Ripple Current Rating
> > The ripple current is sometimes rated for a capacitor in RMS current.
> > Remembering that P = I2R where R in this case is ESR it is plain to see 
> > that
> > this is a power dispassion rating. "

Almost but it doesn't give a number for the heat transfer capability of
the package. That is vitally important, the larger the case, the better
that heat will be transfered to the air and environment and that is
CRUCIAL for keeping the capacitor temperature in reason.
> >
> > Here is a link to the data sheet of the caps I used:
> >
> > http://www.mouser.com/catalog/specsheets/esrl.pdf
> >
> > I haven't figured out the calculations, but  the ripple rating is 1355 ma 
> > @
> > 100 kHz, 50 Volts, 105 C and a "life test" rating of 2,000 hours.  What 
> > kind
> > of life could I expect in the C6 application?

2000 hours is only a quarter of a year. I want my radio to run longer
than that!
> >
> > BTW, I didn't test the caps I removed, but as you can see if you look
> > carefully on the 'before' picture on my site, C9 has a bulge on the top of
> > its casing.

A bulge is a sign of getting hot and expanding the liquid, possibly by
boiling it to steam. There are weak points in the case, sometimes that
leaking electrolyte eats traces from the board nearby.

> TT never told me which caps they replaced the first time
> > around.  Another interesting thing is that all three original caps were 
> > the
> > same specs, but all three were different sizes.
> >
> > http://n6ie.com/A9_Fix.
> >
> >         Ron N6IE
> >      www.N6IE.com
> >
73, Jerry, K0CQ