Need picture of power supply mounted in 11/40 cabinet

pbirkel at pbirkel at
Wed Dec 8 05:32:02 CST 2021

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 <cctech-bounces at> On Behalf Of Marc Howard via cctech
Sent: Saturday, December 4, 2021 10:28 PM
To: General Discussion: On-Topic Posts Only <cctech at>
Subject: Need picture of power supply mounted in 11/40 cabinet


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)?


Marc Howard

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