On 2015-06-14 20:52, Mark J. Blair wrote:
I have a DEC distribution panel and internal cable. The panel has a circuit
breaker, a 15 pin D connector on the outer side for the transceiver, and
another 15 pin D connector on the inner side for the internal cable between the
DELUA card and the distribution panel.
Ok. Good.
The back of the 730 chassis does not have an open slot for the Ethernet
transceiver, as all of the other slots are already occupied. A bracket for the
Ethernet bulkhead panel is screwed to one of the rack's rear panel brackets.
Whoever routed the internal round cable before I got the machine did a less
than perfect job, so it kept getting snagged when sliding the 730 chassis in
and out. The cable jacket has many nicks, but they do not appear to penetrate
the conductor jackets.
Ah. Yes, an extra mounting bracket was not that uncommon. Good if the
cable seems intact.
I've just tried reinstalling it, and things aren't moving smoothly yet. I don't
think that round cable behaves properly in the flat cable flex area, so next I
will see if I can find a clean path between the card cage and a different area
of the chassis where I can route it along the gantry that supports the power
inlet cable. The round cable just doesn't route as cleanly as the original
bundle of flat cables, so I'll need to fiddle and cuss until I get it working
well.
While the round cable sometimes can cause different problems, I can't
say I've ever had any actual problems routing it in the end.
Once I manage to route the internal cable, I'll plug in a DEC AUI cable to the
bulkhead panel, and a DEC 10baseT transceiver, and see if I can get networking
up.
Sounds good.
The first time I started playing with VAXen as a student, there was generally a
long AUI cable running to a vampire tap on thick yellow coax. Sometimes the
coax was routed through the building, and occasionally there would be a vampire
tap down in the stem tunnels with an AUI cable extending into a subbasement.
I've never installed a vampire tap myself.
Long time ago... Lots of "fun". The vampire taps could sometimes be
tricky to get good connections on.
Then a couple years later at a different university, most of the easily
accessible wiring was thin coax, and 10baseT was still newfangled.
Those were fun times.
Johnny
On Jun 14, 2015, at 11:27, Johnny Billquist <[email protected]> wrote:
On 2015-06-14 19:25, Mark J. Blair wrote:
On Jun 14, 2015, at 10:01, tony duell <[email protected]> wrote:
If the connector on the DELUA board is a normal Berg-type header (and I think
it is) then maybe you could
use a piece of (twist-n-flat?) ribbon cable to make an extension that could be
routed through the cable
pan arrangement and then connected to the original DELUA cable back in the rack
cabinet.
That might be a good approach. The DELUA end of the cable has a Berg connector,
and the other end has the typical 15-pin D-sub AUI connector with a slide
latch. I'll look up the cable wiring to see if signals that would best be
twisted pairs are conveniently placed on adjacent odd/even pins, such that
twisted pair ribbon cable would work well electrically.
Or maybe I can use the round cable that I already have, with P-shaped cable
clamps screwed down using the screws at one end of the flat cable clamps. There
may not be enough clearance in the tray for that.
What happened to the original cable and distribution panel?
As a warning - the original distribution panel have a fuse for the 15-pin Dsub,
to avoid excessive power use on the connector. If you go directly from the
board to a transciever, you might run the risk of damaging the DELUA itself if
something goes wrong.
Put another way. The design is to have an internal cable from the DELUA to a
distribution panel at the back of the machine. There you have the 15 pin AUI
connector, which have a fuse. You then had an external AUI cable from there to
your transciever, which traditionally sat on a thick coax. Of course, later on,
you started having thin ethernet. Still AUI cable and transciever, though.
Eventually twisted pair showed up. But you had transcievers for that as well.
And if you have room behind the machine, you could connect the thin ethernet or
twisted pair transscievers directly to the distribution panel connector, so no
actual external cable.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: [email protected] || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: [email protected] || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
