Subject: Re: VS2000 PS quirk? [Was Re: Anyone running on VS2000 w/small memory?]
To: Brian D Chase <bdc@world.std.com>
From: Bob Harbour <bharbour@teleport.com>
List: port-vax
Date: 05/25/1998 21:51:51
On Mon, 25 May 1998, Brian D Chase wrote:
> I guess the PS really wants something to act as a load on those power
> connectors for the disk drives.  I don't know that this is normal behavior
> or not, but it seems like I can reproduce the problem.  We used to have a
> very large number of VAXstation 2000s at my college, and I'm pretty sure
> that we used them as diskless nodes on a VMS cluster with our VAX 6000. I
> remember this, because my roommate and I were very disappointed when we
> could only find one spare VAXstation 2000 with a disk drive for running
> an Ultrix system.  All the other VS2000s we could lay our hands on didn't
> have any drives.
> 
> Can anybody more familiar with VS2000s or maybe even electrical power
> systems shed some light on perhaps why a VS2000 would need a load on the
> drive power connectors to operate normally?

I am not real familiar with the VS2000's, but switching power supplies are
usually designed with a minimum load for the regulator to work properly.
On the old 68k based Apollo's, if you were setting them up as diskless
nodes, there was a dummy load resistor that plugged into the disk drive
power connectors for the same purpose. 

Bob Harbour
bharbour@teleport.com