Seeking H7861 Power Supply (PDP 11/23+)

Noel Chiappa jnc at
Wed Apr 8 10:31:21 CDT 2015

    > From: Jacob Ritorto

    > 2) Assuming H7681, do you know how to wire a chassis that expects H768
    > to work with H7681? Or vice versa?

AFAIK, there is nothing to it.

The backplane normally used with the H786, the H9273, has exactly the same
kind of power connector as the one used with the H7861, the H9276 - a
terminal block. The pinout is, IIRC, identical. There's also a duPont
connector on a flat cable (10 or 12 pin, don't recall off the top of my
head), which carries BPOK and things like that, and that also is has an
identical pinout.

And finally they are the exact same size and shape, with the same fasteners
in the same locations.

Hence my prior assertion that "have looked at both closely, and verified that
they have the same interfaces and physical dimensions, etc, so I think this
will work, but I have yet to actually try it [to absolutely verify it]".

Although I've just noticed that the BA11-N (the H786/H9273) has an H403-A
AC control box, and the BA11-S (the H7861/H9276) has an H403-B. I don't know
what the difference is between the two: higher current rating, would be my
guess, since the H786 puts out 15A of +5V, whereas the H7861 can do 36A.

But no, the BA11-N says its max input is 12A at 120 VAC - although that
includes powering an auxilliary AC outlet. The H756 P/S alone draws 5.5A; the
H7561 is the exact same. (Wow, double the efficiency...) So the auxiliary
outlet must be the difference - sure enough, the BA11-S doesn't have one.

So I still think you're good to go! :-)


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