VAX 11/750 power supply fault

[Antonio Carlini]

J Blaser wrote:

> I'd love to repair it, but I'm certainly not as smart as Tony, nor am
> I likely
> to ever figure out the faulty component(s) directly.  There is a main
> 'motherboard', two plug in PCBs, and other bolt-on components galore,
> and while
> I can follow some logic circuit diagrams, I'm clearly out of my
> league with analog/PS stuff.

You seem to have managed to wiled a voltmeter and not hurt yourself
inside the PSU. Sureley the worst that can happen is that you'll
end up at the point where you need to fix component X and you
are unable/unwilling to do so?

People have been talked through some tricky procedures on this
list ... For that matter this is maybe the 3rd VAX-11/750 with
the "REG FAIL" fault and I don't recall ever hearing of one
getting fixed. Someone has to be the first :-)

>  Besides, I haven't been able locate  schematics for this power
> system.  Soooo....

There should be a full set of schematics on Manx: http://vt100.net/manx.
I scanned a full set for the first person I came across with this
problem, so while I'm not 100% sure the PSU schematics are in there,
I am 99% sure ...

Antonio

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