Replacing MicroVAX II PSU With a Modern PSU

Jon Elson elson at
Tue Nov 24 20:07:58 CST 2015

On 11/24/2015 05:52 PM, Mark Wickens wrote:
> 4.       The most difficult bit, I suspect, would be the PSU LTC signal ,
> which I believe is some kind of clock. I don't know what the spec of the
> signal is, but I will get a scope on a working one to see (NB don't want to
> risk a working PSU on this machine in case it was a problem with the
> machine
> itself that caused the first PSU to fail, I don't mind sacrificing a modern
> PSU if need be).
The line time clock is a vestige of the Q-bus LSI-11 
heritage.  As far as I know, there is a reserved bus signal, 
but it was NOT implemented on the UVAX-II system.  (I don't 
have my print set anymore.)


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