VAX 4000-500 PSU Overload?

Robert Jarratt robert.jarratt at
Fri Dec 11 11:06:08 CST 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Richard
> Loken
> Sent: 11 December 2015 16:45
> To: General Discussion: On-Topic and Off-Topic Posts
> Cc: General at
> Subject: Re: VAX 4000-500 PSU Overload?
> ...
> My doctor once said to me that all problems in the head involve teeth and
> can safely make a similar exageration:
> 	All electronic failures involve capacitors
> And this becomes (most repulsively) even more true when switch mode
> power supplies are involved.  Keeping that in mind will usually help with
> diagnosis.

Well, I have the exception that proves the rule. My H7864 PSU (from an rtVAX
1000, same PSU as MicroVAX II) had a switching transistor and resistor fail,
no cap failures....




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