Are there any documents for a DEC 872-A Power Controller floating around?
The 872-A is a 12A, 110V power distribution/control unit that I have in
the bottom of my "corporate rack".
Specifically I'm interested in what the signaling is on the two, 3-pin
Molex jacks labled "DEC Power Control Bus", which presumably is a means
to remotely control the power to the devices in the rack via this PDU.
All power cotnollers after a certain date (early 1970s, IIRC) use the
same 'power control bus', os the manual and/or printset for any of them
would be a good start.
From what I rememebr, the 3 pins are ground,
ground-for-on, and
ground-for off, 'off' taking priority over 'on'
if both are grouded.
There is no lartching in the power controllers.
You interconnect all the power controllrs in the system with
straight-through cables. The power swtich on the CPU box is connected
betweem the ground and ground-fro-on wires, so that turning this on
acrviates all the controllers and powers up everythjing. Over-temperature
swtiches and the like are connected betweem ground and ground-for-off, so
thatr if any device overheats, the whole system shuts down.
Thes signals are not TTL level. They may be up to 24V, nd you may have to
sink enough currnet to operate a reed relay. Just in case you want to
design your own swithcing units...
-tony