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

[Dr. Gerald N. Johnson]

On Wed, 2008-06-25 at 09:50 -0700, pfizenmayer wrote:
> Here is a link to a pretty complete SPICE analysis of the A9 board - its the 
> bottom line in  the table. The issue is RIPPLE current.
> 
> Hank K7HP
> 
Then low ESR and high temperature rating are a benefit, but the
fundamental is that the capacitors need to be rated FOR the ripple
current. Good electrolytic makers know and publish such ratings. Some
might have related it to ESR and heating, but the better makers list
ripple current ratings directly.

For fixing older stuff, I'm liking the Vishay Sprague Atoms line because
it was good 40 -50 years ago and has a large case for the
capacitance/voltage ratings giving a larger surface for heat
dissipation. They may be very difficult to fit to the PC board though.

The run of the mill miniature electrolytics are cheap but junk, many
won't pass my power factor tests straight from the distributor's drawer.
Low E.S.R. and high temperature probably are the best that can be
bought, but look for a ripple current rating and pick the highest to
give better life.

73, Jerry, K0CQ