Re: Need picture of power supply mounted in 11/40 cabinet
> From: Marc Howard
> I've got an 11/40 I'm going to start working on. Problem is that there
> are two power supplies (H742 and H7420) that came with it but neither
> was mounted in the rack.
-11/40's in general only have one of those large H742x suppplies in a rack.
The documentation and prints all show only a single one - in fact, the 11/40
power harness (which is specific to the KD11-A backplane, at the CPU end) can
only attach to one. The KB11 machines (-11/45 and /70) use two, but their
harness has provision for two.
I don't know of a DEC document that lists the difference between the H742 and
H7420, but my CHWiki page for them:
https://gunkies.org/wiki/H742_Power_Supply
gives what I think is a pretty good list; any errors or missing details would
be appreciated.
> Also how is the power cabling routed (I think I'm missing this part)?
That's going to be a hassle, replacing the main harness! Especially since
production of the 8-pin MATE-N-LOK connector shells used to interface to the
H744/etc 'bricks' - part numbers here:
https://gunkies.org/wiki/DEC_standard_modular_regulators
are out of production, although some vendors have residual stocks. Hoard them
while they last!
The "PDP-11/40, -11/35 (21 inch chassis) system manual" (EK-11040-TM-002):
http://www.bitsavers.org/pdf/dec/pdp11/1140/1140_SystemManual.pdf
has pretty good coverage of the harness; the back end of Chapter 6 covers it
in detail. That's a lot easier to understand than the FMPS:
http://www.bitsavers.org/pdf/dec/pdp11/1140/PDP-1140_System_Engr_Drawings_Rev_P_Jun74.pdf
so read that before you tackle the prints.
Note that there are two different kinds of harness, depending on whether the
machine has MM11-L (-15V) or MM11-U (+20V) core memory. Unless you're
planning on using one of those, you can probably ignore that, though.
Any questions, ask here right off; we have a lot of expertise! :-) ('My'
first -11 - as in, one I was in charge of - was a -11/40. Fond mempries!)
Noel
RE: Need picture of power supply mounted in 11/40 cabinet
Marc: Do you have the 11/40-specific wiring harness? Assuming that you do it's a bit tricky -- not so much mounting a given supply (aside from the fact that they are heavy and awkward to work with even when minimally populated), but because there is a very tight tolerance between them to thread the wiring harness. I've determined the hard way that you really need to install the lower one first, then the harness, then the upper one. At least for me it wasn't practical/possible to install the harness after-the-fact. There's also a bit of work involved in threading both of the AC power cables plus the pair of power-control cables (assuming that you're using a DEC power controller) via the right-side vertical rack channel -- which also interact with the power harness placement. Once everything is cabled-in-place the result is maximally compact, but getting there is not simple. Yes, the power cable wiring isn't well-described anywhere IMO. You have to stare at the puzzle-pieces for a while and "dry fit". Harness shape/stiffness helps eyeball how to fit the pieces together, but the importance of the rack vertical side-channel in making everything fit is not, IMO, made at all clear anywhere in the various documentation -- although it can be inferred from careful examination of a few graphics in various documents. The 11/40, the 11/45-50-55, and the 11/70 share the same design in this respect so documentation for one will serve you well in any of these cases. If you can tackle the task *before* installing the BA11 chassis you'll find it easier. If you're not using a standard DEC rack or don't have an equivalent vertical side-channel to work with then IMO you'll need to get very creative ... and the 11/40-specifics wiring harness may not work at all and you'll need to build your own. Fortunately I didn't need to explore that path ... Good luck! -Original Message- From: cctech On Behalf Of Marc Howard via cctech Sent: Saturday, December 4, 2021 10:28 PM To: General Discussion: On-Topic Posts Only Subject: Need picture of power supply mounted in 11/40 cabinet Hi, I've got an 11/40 I'm going to start working on. Problem is that there are two power supplies (H742 and H7420) that came with it but neither was mounted in the rack. Could someone post/send/etc. photos of how the power supply mounts in the rack? Also how is the power cabling routed (I think I'm missing this part)? Thanks, Marc Howard
Re: Need picture of power supply mounted in 11/40 cabinet
I have seen both upper and lower...if you fish through you can find what you need here: https://www.vintagecomputer.net/digital/PDP11-40/ https://www.vintagecomputer.net/digital/PDP11-40_full-height/ https://www.vintagecomputer.net/digital/PDP11-40_industrial11/ Bill On Mon, Dec 6, 2021 at 2:03 PM Gregory Beat via cctech < cct...@classiccmp.org> wrote: > Power Supplies, due to their Weight, are placed at the bottom of Racks > (prevent tip overs / weight distribution). > https://avitech.com.au/?page_id=366 > > The PDP-11/70 Maintenance and Installation Manual (EK-11070-MM-002) > explains that the basic PDP-11/70 system components are located in a double > cabinet as shown in Figure 1-1 of that manual. > > https://i0.wp.com/avitech.com.au/wp-content/uploads/2016/05/major-assemblies-fig-1-1.jpg > > greg > > > Date: Sat, 4 Dec 2021 19:28:01 -0800 > > From: Marc Howard > > To: "General Discussion: On-Topic Posts Only" > > Subject: Need picture of power supply mounted in 11/40 cabinet > >
Re: Need picture of power supply mounted in 11/40 cabinet
Power Supplies, due to their Weight, are placed at the bottom of Racks (prevent tip overs / weight distribution). https://avitech.com.au/?page_id=366 The PDP-11/70 Maintenance and Installation Manual (EK-11070-MM-002) explains that the basic PDP-11/70 system components are located in a double cabinet as shown in Figure 1-1 of that manual. https://i0.wp.com/avitech.com.au/wp-content/uploads/2016/05/major-assemblies-fig-1-1.jpg greg > Date: Sat, 4 Dec 2021 19:28:01 -0800 > From: Marc Howard > To: "General Discussion: On-Topic Posts Only" > Subject: Need picture of power supply mounted in 11/40 cabinet
