IBM 4331 Mainframe 3 phase converter

Bob Rosenbloom bobalan at
Thu May 4 00:04:02 CDT 2017

I use a solid state one, an older version of this:

Bought on ebay quite a few years ago.

I also have a small Phoenix rotary phase converter, also from ebay. This 
one seems to have unbalanced outputs.
I believe it is for motor loads only.


On 5/3/2017 1:23 PM, Curious Marc via cctalk wrote:
> Let me know what you come up with for the 3 phase converter solution. I have the exact same problem right now to provide power for my 3 3420 tapes and the 3803 controller. Also have 220V 50A single phase coming in the shop (er, garage), courtesy of the EV charger.
> Marc
> On Apr 30, 2017, at 9:38 PM, Guy Sotomayor Jr via cctalk <cctalk at> wrote:
> Just to let folks know that I finally moved the IBM 4331 Mainframe this past weekend
> from where it was currently stored to my shop.  Pictures are here:
> <>
> As can be seen in the pictures, it filled a 26’ box truck that I had rented for this purpose.
> Right now I just have it placed somewhat in my shop.  Some early tasks will be:
>    * I have to verify that I have everything.  Even if I missed some items, they won’t be
>      scrapped.  I just need to go over what is currently in my shop and verify that I didn’t
>      leave anything behind.  I’m mostly worried about cables at this point.
>   * I have to figure out some way to produce enough “clean” 3-phase power to run the
>     peripherals (the CPU is 220v single phase) as I only have 220v single phase coming
>     into my shop.
> Starting to power it up will probably be a while yet.  ;-)
> TTFN - Guy

Vintage computers and electronics

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