[time-nuts] HP 3586B Power Supply Failures

[David]

On Thu, 22 Mar 2012 12:04:30 +0100, Attila Kinali <attila at kinali.ch>
wrote:

>On Wed, 21 Mar 2012 22:33:49 -0700
>"John Miles" <jmiles at pop.net> wrote:
>
>> I did this for a while, but I eventually realized that new
>> "computer grade" electrolytic capacitors no longer have the same
>> quality levels that they must have had in the 1970s and 1980s.
>>  Back then, orders of magnitude more of them would have been used in
>> production than are used today, and the manufacturers would have paid
>> more attention to what they were doing.   After my first few encounters
>> with high-ESR parts out of the retail box, I stopped replacing good ones. 
>
>That's not really true. More electrolytics are used today than were in the
>70s and 80s, mostly because a lot more electronics is build today.
>What is different though is that those electrolytics are more optimized
>to be cheap than they were before. Which means that you have to more
>carefully select the capacitor you are going to use. Main stuff you have
>to look for is: ESR, maximum ripple current, operating temperature.
>Especially the ripple current is important as this is what kills most
>electrolytics in "cheap" or not well designed circuits these days.

In the two Tektronix PS503As that I just rebuilt, out of 4 big
aluminum can style input and 4 small axial style output electrolytic
capacitors, the one of each set that went bad where marked "made in
mexico" and had no identifiable manufacturer.  The other 3 of each set
were clearly marked Mallory for the large input ones and Sprague for
the small output ones.

In some old switching power supplies I fixed a couple of weeks ago,
the axial Cornell Dubilier capacitors were in excellent shape while
almost every other capacitor was worn out.