20 Jan
2009
20 Jan
'09
2:34 p.m.
I have a VAX 6000, too (in my personal collection) and it's a different beast than the
VAX-11s, for sure. The VAX-11 actually runs 110V single phase to each PDU and other
component (e.g. LSI-11). The VAX 6000 takes in its mains feed and turns it into 300VDC,
which goes to each of the 'regulators' (actually switchers) to be transformed to,
for instance, 5V at arc-welding current levels. It also taps off a single leg to run a
24V supply, only loosely regulated if at all, that runs fans, and is also regulated to run
the power-on sequencer. There's no transformer involved unless you're on a 50Hz
system, according to DEC's documentation. -- Ian
________________________________________
From: cctalk-bounces at classiccmp.org [cctalk-bounces at classiccmp.org] On Behalf Of
Sridhar Ayengar [ploopster at gmail.com]
Sent: Tuesday, January 20, 2009 1:34 PM
To: On-Topic and Off-Topic Posts
Subject: Re: Running 3 phase 780s on single phase power
Paul Koning wrote:
And finally, if you have a system that actually has a
3-phase input to
the DC supply (for example, 6 diodes from 3 center-tapped windings
feeding the ripple filter), then rewiring that input as 3 separate
single phase circuits is not going to work quite right, because you
will then have inadequate filtering (having replaced 360 Hz ripple by
120 Hz ripple). It doesn't sound like this shows up in VAXen; I don't
know if it does in the KL-10; but I do know it is a consideration if
you're working on a CDC 6000 series machine because it has such supplies.
Isn't that how the VAX 6000 is set up?
I run a VAX 6000 on split-phase and it works just fine.
Peace... Sridhar