In march last year there was a discussion on this list, reproduced in
the vax-bsd faq, between Andre Skarzynski and Leon Heinkelein
concerning the conversion of a VAX6220 to single phase.

Unfortunately this does not mention the specific wireing changes
required. I have been unable to contact either Leon or Andre, Leon being
unknown at the e-mail address in the message.

I would like to attempt this conversion on a 6310, but am unsure how and
hoped that perhaps someone on this list could help me or put me in touch with
these gentlemen. My main questions :-

Is such a conversion feasable ? Is the resulting power (305v?) close enough
to 300v that it doesn't matter ?, or will it eventually blow the components
because of this or the input difference of 220v against 208v ?

Where do you connect the 2 single phase cables and the ground cable ? I
assume on the H405, but where ?

And how do you bypass the 50hz transformer ? Is it a simple matter of
disconnecting the 380v input and 208v output wires from J2 and J3 and
somehow connecting them to each other ? There are 4 wires from the H405 to
the J2, but 6 wires from J3 to the H7206, what are they ? and what gets
connected to what ?

Lastly, what effect will this conversion have on the 2 220v outlets, FL3 and
FL4, and on the 2 DEC power-bus outlets, FL1 and FL2 on the H405 ?

I'm moving house on the 21st and can't immediately put in 3-phase, so unless
I can get this 'hack' working my vax will be unuseable for months.

Thanks for any help. Please cc any replies to me as I'm not subscribed to
this mailing list.

See you,

Steve.

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_____________________________________________________________________________
Stephen Peterson,				     THOT System Consultants
Utrecht POP for The OpenWorld Foundation,	     email: stv@utrecht.ow.nl
Utrecht, NEDERLAND. 00-31-30-2801090			    stv@cistron.nl