I'm sorry this took so long...I'm in the process of moving.

   This system currently contains one 600-series CPU, two 128MB memory 
modules, and one XMI cage containing two DEMNAs, one CIXCD, and one 
KDM70.  The actual current consumption is a bit over 6A, not 4A as I 
mentioned before...I've actually just taken a more accurate reading 
using a clamp probe, while before I was relying on the load current 
display of my UPS (APC Matrix 5000) and there must've been some other 
fluctuations going on when I looked at it.

   The conversion is frighteningly simple.  The entire machine runs on 
48VDC...even that big blower.  The 208V 3-phase power goes through a 
circuit breaker and a set of filters, then each phase is connected to 
the input of each of three very large 48VDC switching power 
supplies...which are even clearly labeled as having 120VAC inputs.

   These supplies appear to be fully independent, each using 
phase-to-neutral power ("wye"), not phase-to-phase power ("delta").  My 
first VAX 7000 has only one of these regulators installed (there are 
two blank panels where the other two would go), presumably because it's 
a small config...my second VAX 7000 has two processors, more memory, 
and two XMI cages...and a scary quantity of DSSI interfaces...and it 
has two of the three 48VDC power supplies installed.

   Anyway, all you have to do is connect the 120VAC inputs of those 
power supplies directly to 120VAC, bypassing pretty much everything in 
the power input box.  Alternatively (and this is what I did) you can 
just connect the appropriate hot lead on the 3-phase power connector to 
the hot lead of a 120VAC power cable, the neutral to the neutral, and 
the ground to ground...and plug it in.

   A very VAX 7000-knowledgeable friend of mine (Eric Dittman) advises 
that it's safest to throw the main breaker and wait several seconds for 
power to stabilize before turning the front-panel power switch...he 
says he's fried a processor module by not waiting.

   I've not yet tried this with more than one 48VDC regulator installed, 
but I'm confident that it will work, due to the apparent independent 
nature of those three 48VDC switching power supplies.

   I am now happily installing VMS on the machine, which is *quite* 
zippy.  I have it connected to a rack of SCSI disks controlled by an 
HSJ40, connected via CI and a star coupler.  The aforementioned Eric 
Dittman is sending me a pair of HSJ50s so I can beef it up a bit.

   I'm looking for another CIXCD (XMI CI controller) with cabinet kit so 
I can get the second 7000 on the cluster.  If anyone has one available, 
please let me know.  I could also use a CIQBA or two, and some *short* 
CI cables if anyone has some.

   FYI (I'm hacking as I'm typing this), adding a second 600-series CPU 
module bumps the system's current consumption up by not quite one 
ampere.  Adding a 512MB memory module increases its consumption by 
about 0.5A.

         -Dave

On Dec 19, 2003, at 12:57 AM, Lord Isildur wrote:
> way cool!
> and only 4 amps, not bad... what boards are in it?
> isildur
>
> On Sat, 13 Dec 2003, Dave McGuire wrote:
>
>>
>>    I am too tired to type up the exact details right now, but..
>>
>>    As of a few minutes ago, I am successfully running a VAX 7000 on
>> single-phase 120VAC power.  It's a mid-sized config, and it's only
>> pulling about four amps (no disks yet).
>>
>>    The modification is even easier than for the VAX 6000.  ANYONE can 
>> do
>> this...it is trivial.
>>
>>    I count this as a major victory, and I am VERY happy!
>>
>>    Thanks to Bob Keys for some hints that led me down the right path.

--
Dave McGuire                      "My tummy hurts now, but my soul
St. Petersburg, FL                 feels a little better."     -Ed