H750 (PDP-11) power on?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu May 27 18:15:07 2004

>
> I do need some definmitions.
>
> > What about the breaker on the power controller?
>
> Power controller? Same as a power supply?

No, thw power controller is a separate box. It contains a contactor (big
relay) and some control circuitry. It has serval mains sockets that you
plug your peripherals (disk drives, etc) into, and the 3 pin power
control connectors that I mentioned.The idea is that turning on the CPU
console switch will then power up all the peripherals too (you can
daisy-chain power controllers so that your entire system, no matter how
large, comes on at once).

> This one has the PSU on the right side with no obvious
> switches that I've yet found (maybe I have to change my
> definition of obvious).

> Breaker as I said is a just a small button, or,
> it's hidden under a cover somewhere... more looking.
>
> > And is this the 5.25" or 10.5" high CPU box?
>
> 10.5

10.5" box with the PSU on the right? The only 10.5" 11/10 I saw was in
the same box as the 11/34 and had the PSU across the back. Oh well...

If this is like the 5.25" box with the PSU flat on the right and the
cards going in from the left side, then you should have no problems
powering it up by connecting the mains cable to mains and frobbing the
microswithcs (watch out, one carries mains!).

>
> > On the power controller there should be a little toggle
> > switch. This should be set to 'Remote'.
>
> Not found (yet). This is one of the oldest PDP's made.
> Second model, I believe.

Even if you're only considering PDP11s (and there were plenty of machines
before those), the 11/20, 11/15 and 11/45 all predate it.

>
> > Try connecting the CPU mains cable directly to the mains
> >(without the power controller)...
>
> CPU mains cable sounds obvious, but what I have may be

'Mains cable' is what you probably call a 'power cord'...

> the power controller cable(?)

If you just have the CPU box, you don't need to worry about the power
controller connectors

> Like I said, please define it for me.
>
> Yes, I just looked around again with a flashlight, and peering under
> the varouus grillworks, stopping just short of removing the PSU cover.
> No circuitbreaker-switch. The two three pin ports that I mentioned first
> up are located directly in front of a fair sized relay. Will try switching

This doesn't sound like any 11/10 I've ever seen....

Hang on. On some early PDP11s (and PDP8s for that matter) the power
control bus was wired differently. You have daisy-chain all the units and
put jumper plugs in each of the end 2 sockets. Try shorting middle to top
on one socket and middle to bottom on the other and see what happens.

-tony
Received on Thu May 27 2004 - 18:15:07 BST