[rescue] VAX 11/750s - Re: Linux wet paint, was Re: Spark10 CPU question (must fix - SPARC damnit :-) )

Josh Dersch derschjo at gmail.com
Tue Dec 20 11:25:02 CST 2016

On 12/20/16 7:23 AM, John Hudak wrote:
> so, basic electronics: Electrolytic capacitors dry out/leak over time...and
> coming up on ~ 35 years, I'd say they are well past their  design life.

Yes, I'm aware, but thanks.

> Back in the day, SMPs were brutal on capacitors - caps were not formulated
> to withstand the 30-60+KHZ pounding of of the design.  Capacitor
> formulations over the last 15+ years have changed to better hold up when
> used in HF switching applications.
> Caps are specifically designed for SMP applications with low ESR.
> While you are at it, better replace all those carbon resistors as they
> degrade over time, but not nearly as much as the capacitors.
> I'd say your observations about the performance of 35-40 yo SMPs are a
> overly high on expectations.
My observations about the performance of 35-40 yo SMPs are exactly that: 
observations.  I had no expectations going in, (apart from expecting 
them to need repair or at least preventive maintenance); what I relayed 
to this list is the extent of the repair necessary.

- Josh

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