pdp11/45

From: Jacob Ritorto <jritorto_at_nut.net>
Date: Mon Aug 30 21:02:13 1999

Hey Tony (Duell), [or anyone else interested for that matter]

        want to help me with my 11/45 again? I just found out that I
again have too much time on my hands, so I'm ready to try some more. I've
moved to a new house and brought my entire pdp11 collection with me (most
of it is in the garage). I placed the '45 (w/ two TU10s, a stack of
RK05s, a rack of SMD disks, and a tek4015) in the 'great room' here and
there's plenty of room to tinker. BTW, it looks really cool with my red
walls. I think I'm going to keep it here permanently.

        Here's a little refresher as to what we were on last time:

TIA

jake

PS. Is this a grant thing perhaps? What if somebody took a DMA device
out of one of the slots without replacing the jumper? Would it do this?

On Sat, 19 Jun 1999, Tony Duell wrote:

> >
> > Hey All, sorry I took so long to get back to this topic, but things have
> > been hectic and there's been no time for Geek Stuff. :( :( :(
> >
> > I removed the extraneous things from the bus (namely the external box of
> > memory and the three core SUs), so now I have only the 11/45 backplane
> > with an M930 in the last slot. Still the same symptoms on the front
> > panel.
>
> OK, it _is_ an M930 terminator and not an M9302, then. I was going to ask
> you about that. The reason is that the later M9302 board can 'lock the
> unibus' if there are grant problems. An M930 won't.
>
> >
> >
> > The probe of J14 revealed the following:
> >
> > on 2&3: exactly 15VDC (this is the 15v source you ask about being
> > present and correct, isn't it?)
>
> Sounds perfect to me. And yet _both_ H745s are giving no output?
>
> There should be an H745 in the rear slot of the top PSU. It has an 8 pin
> connector on top. Pin 1 is the -15V output. Pins 4 and 5 are a +15V
> (control-ish) input.
>
> > on 8 : about 4VDC
>
> Sounds right.
>
> > on 10 : Zero.
>
> Puzzling, but not necessarily a problem yet...
>
> > on 12 : about 4VDC
>
> Sounds right again.
>
>
> >
> > To answer a few of your other questions:
> > I don't have a KM11 maintenance board.
>
> Pity. I didn't think you'd have one, but it was worth asking.
>
> > I have the 8-pin, flat power connectors on my CPU.
>
> I think _all_ 11/45 systems have the 8 pin connectors on the CPU
> backplane. The difference is how the extra System Unit backplanes get power
> On old machined (pre S/N 2000?) there was a PCB on the inside back of the
> CPU box. It had a number of 8-pin flat connectors on it. The system units
> plugged into that.
>
> On later machines there was a board on top of the CPU fram on the RHS
> (over the 'hole' that goes over the PSUs). System units had the
> conventional 15 pin and 6 pin connectors.
>
> >
> > Which schematics are you using?
>
> I have the DEC field maintenance printset for the 11/45 (both versions).
>
> > What should I do next?
>
> You mentioned that 'both -15V outputs are low' Which pins of which
> connectors are you measuring? At the PSU there are 3 -15V lines on my
> diagrams - pin one of P21 (top PSU rear slot H745), pin one of P25
> (bottom PSU, front slot, H745) and pin 4 of P22 (bottom PSU, 12 pin
> connector on transformer housing). Which (any/all?) of those are missing?
>
> -tony
>
>
>
Received on Mon Aug 30 1999 - 21:02:13 BST