PDP-11/34A / BA11-K PSU

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu May 22 15:24:00 2003

> Hi.=20
>
> I got some more parts of that disassembled PDP-11/34A yesterday. I think
> I have now all PSU parts
> - power inlet unit with mains cable, circuit breaker ... and a PCB that
> looks like a small PSU.

If that's a PCB that covers the top side of that module, then it is a
small PSU (+15V at a few amps, and also the ACLO, DCLO, LTC signals).
There should also be a little PCB inside the module which controls the
mains relay, I think.

> - one big transformer

OK

> - one small transformer

I don't remember there being a second transformer inside the BA11-K. Is
this possibly part of the battery backup option (to go with the charger
PCB below -- this doesn't fit inside the BA11-K)

> - one H785 battery backup regulator module
> - one H745 -15 PSU module
> - two H7441 +5V PSU modules=20

OK -- that should be enough to run the machine. You don't _need_ the
battery backup unit, BTW...

> - a PCB that is labled "BATTERY CHARGER"

AFAIK the battery backup unit was a separate box that contained the
batteries, the charger PCB, and probably the small transformer.


> - a bag full of screws
>
> Some time ago I got the front half of the BA11-K, i.e. a card cage with
> the system units, all UniBus cards, power distribution panel and front
> panel.
>
> Obviously missing:=20
> - back of the BA11-K where the PSU bricks, transformers, ... are mounted
> - fans
> - bulkheads for the console serial line, the serial multiplexer, RK07,
> ...
> - UniBus extender and terminator. [1]=20
>
> I got the card cage, power distribution panel, system units and all
> UniBus cards in one piece, but disassembled it to clean it. I know how
> to remount that, but I have no clue how all the PSU parts fit togeter

YOu really need the printset. The bricks connect to the 8 pin mate-n-lock
plugs wired to the distribution PCB (but you must get them in the right
places!), then there's a little cable that connectes between the +15V PSU
and the distribution PCB. The transformer connects to that cable, to the 8
pin mate-n-lock on the distribution PCB and to the 4 pin connector on the
front of the power controller. THe power switch wiring from the front of
the cabinet connects to one of the 3 pin connectors on the power
controller. The fans connect to the primary side of the transformer, BTW.

> and if there are some parts missing I didn't list above. It would be

Maybe the odd cable or connector is missing, but you have the main parts.

-tony
Received on Thu May 22 2003 - 15:24:00 BST