20 Jan
2012
20 Jan
'12
2:14 a.m.
From: Eric Smith
Sent: Wednesday, January 18, 2012 11:06 PM
Richard wrote:
> I'd advise you to consult with the folks at
the Living Computer
> Museum. IMO, they did a wonderful job of replacing the original power
> supply in their machines with a modern efficient switching design.
My understanding is that they replaced the entire ECL
power supply
system with modern switchers.
On our 1095, yes. The 2065 has not undergone surgery quite as extensive
as that. We re-built the DEC power supplies with new capacitors [thread
tie]. The 1095 was the second effort, as an experiment.
I plan to keep the original power supply front end
(three-phase to -12V
DC), and only replace the linear regulator modules (nine each -12V to
-5.2V at 35A, and four each -12V to -2.0V at 35A) with switchers. That
preserves (and actually improves upon) the AC power-fail functionality
of the system, allowing the processor state to be written to RAM, to
allow resumption of execution on power restoration. (Assuming that the
RAM is nonvolatile, which in the original machines was accomplished by
either core memory, or battery-backed DRAM.)
However, I plan to get the machine working with the
original regulators
before I change anything.
> It was all done in such a way that the upgrade was
fully reversible to
> restore the machine to it's original condition.
Naturally I plan to do that also.
Well worth it.
Rich Alderson
Vintage Computing Sr. Systems Engineer
Vulcan, Inc.
505 5th Avenue S, Suite 900
Seattle, WA 98104
mailto:RichA at vulcan.com
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/