How does one hook up a pdp-8 to remotely turn on an RK05?

[tradde]

This may sound like a dumb question, but I can't find anything that talks about it. I'd like
to have my 8e power switch also turn on the RK05s. I have the proper cable I believe.
I know the power distribution for the RK05 needs to be set to remote. But where does
the other end go? I thought it should go to J1 or J2 on the 8e. Is there another connector
for this? It would be so much nicer if everything powered up from the key. Thanks.
Tim R

 

[pontus]

I haven't seen the backside of an RK05, but I believe the cable from the PDP-8 should go to a power distribution unit (PDU) in the bottom of the rack, and you connect your peripherals to the remote controlled PDU sockets.

 

[tradde]

I haven't seen the backside of an RK05, but I believe the cable from the PDP-8 should go to a power distribution unit (PDU) in the bottom of the rack, and you connect your peripherals to the remote controlled PDU sockets.

Well, when I got my RK05s they were in a separate rack from the 8a. That was the desk
8a that Crawford just got from me. I eventually got a real 8e, and have never tried to
hook it up to power everything on from the 8e key. I believe it can be done. I don't
think I want to plug the 8e into the same distribution panel. It's not a real heavy duty
ones like the 30a guys. And I don't see how that would do what I want. Somehow the
8e should have one of those 3 hole jumpers that cables to the same thing on the distribution box. I just can't find anything that talks about it. I looked in the maintenance manuals
thinking they would explain all those jumpers. I'll just have to keep looking.

 

[vrs42]

This may sound like a dumb question, but I can't find anything that talks about it. I'd like
to have my 8e power switch also turn on the RK05s. I have the proper cable I believe.
I know the power distribution for the RK05 needs to be set to remote. But where does
the other end go? I thought it should go to J1 or J2 on the 8e. Is there another connector
for this? It would be so much nicer if everything powered up from the key. Thanks.
Tim R

There's nothing magical about the back end of an RK05, so as far as I know you just plug it into one of the switched outlets of the power controller.

The real magic is interfacing the interlock stuff on the back of the 8/e to the power controller.

The power controller wants essentially a switch closure between pins 1 and 3, on each side of the connector. The 8/e, unfortunately, doesn't provide this.

What the 8/e presents is a small DC voltage at J1, which has to be pulled to ground (pin 3) to activate the machine. The default jumpers wire J1-1 to the J1-2 which is the thermal cut-out switch, the other side of which is connected to J2-2 through the power switch J6. The external jumper connects that to GND at J2-3, providing the closed circuit to trigger the relay that activates the machine.

However, that means that J1-2 and J2-2 are essentially opposite sides of the power switch.

So, I believe you can essentially jumper J1-1 to J1-3, bypassing the power switch altogether, then plug the 8/e into one of the other switched outlets. At that point everything should come on at once, when you switch the power controller to "local" mode. Don't run it like that though, as you've bypassed the thermal cut-out on the 8/e, as well as it's power switch.

If you now cable J1-2 to pin 1 on the power controller, and J2-2 to pin 3 on
the power controller, you'll have the switch closure that the power controller needs. Set the power controller to "remote", and both devices should come on when the 8/e power switch is activated. Both should also go off if the 8/e thermal cut-out ever trips.

I haven't actually done this yet, so you'll want to check my work and see if what I'm saying makes sense first. The relevant 8/e drawing is H724-0-1 or H724-A-1.

Vince

 

[tradde]

There's nothing magical about the back end of an RK05, so as far as I know you just plug it into one of the switched outlets of the power controller.

The real magic is interfacing the interlock stuff on the back of the 8/e to the power controller.

The power controller wants essentially a switch closure between pins 1 and 3, on each side of the connector. The 8/e, unfortunately, doesn't provide this.

What the 8/e presents is a small DC voltage at J1, which has to be pulled to ground (pin 3) to activate the machine. The default jumpers wire J1-1 to the J1-2 which is the thermal cut-out switch, the other side of which is connected to J2-2 through the power switch J6. The external jumper connects that to GND at J2-3, providing the closed circuit to trigger the relay that activates the machine.

However, that means that J1-2 and J2-2 are essentially opposite sides of the power switch.

So, I believe you can essentially jumper J1-1 to J1-3, bypassing the power switch altogether, then plug the 8/e into one of the other switched outlets. At that point everything should come on at once, when you switch the power controller to "local" mode. Don't run it like that though, as you've bypassed the thermal cut-out on the 8/e, as well as it's power switch.

If you now cable J1-2 to pin 1 on the power controller, and J2-2 to pin 3 on
the power controller, you'll have the switch closure that the power controller needs. Set the power controller to "remote", and both devices should come on when the 8/e power switch is activated. Both should also go off if the 8/e thermal cut-out ever trips.

I haven't actually done this yet, so you'll want to check my work and see if what I'm saying makes sense first. The relevant 8/e drawing is H724-0-1 or H724-A-1.

Vince

I'd have thought there would be a direct jumper to connect. I guess I will just leave it
as it is then and power on both separately. Thanks for the info.

 

[vrs42]

I'd have thought there would be a direct jumper to connect. I guess I will just leave it
as it is then and power on both separately. Thanks for the info.

I don't think it's that bad. If my "ascii art" comes out OK:

O-\
O-+--\
O-/   \
       \-----------O
                   O
       /-----------O
O-\   /
O-+--/
O-/

where "+" means two wires cross, but do *not* connect. You can even connect the two little loops, if it helps to keep the cable neat. The end with two connectors goes to the 8/e, and the end with a single connector goes to the power controller. The two connectors to the 8/e can be swapped without causing problems.

You might have to order the connector housings and pins to build such a thing, though.

Vince​

 

[tradde]

I don't think it's that bad. If my "ascii art" comes out OK:

O-\
O-+--\
O-/   \
       \-----------O
                   O
       /-----------O
O-\   /
O-+--/
O-/

where "+" means two wires cross, but do *not* connect. You can even connect the two little loops, if it helps to keep the cable neat. The end with two connectors goes to the 8/e, and the end with a single connector goes to the power controller. The two connectors to the 8/e can be swapped without causing problems.

You might have to order the connector housings and pins to build such a thing, though.

Vince​

I had a cable for this that I though would just work. It's got the correct ends and 3 wires
end to end in the plastic plug in things. It's no big deal to power both on as I have
been doing all along. Just thought it would already be ready for this.

 

[vrs42]

I had a cable for this that I though would just work. It's got the correct ends and 3 wires end to end in the plastic plug in things. It's no big deal to power both on as I have been doing all along. Just thought it would already be ready for this.

I also thought of another solution that retains the existing ground jumper on the 8/e, and runs pins 1 and 3 of the other 8/e connector to pin 3 (GND) on the power controller, and pin 2 on the 8/e connector to pin 1 on the power controller. That's easier in a way, but you'd have to pay attention to which is pin 1 and which is pin 3.

But yours is just 3 wires wired straight through, right? That would be the newer power bus -- perhaps PDP-11 or the like.

Vince​

 

[tradde]

I also thought of another solution that retains the existing ground jumper on the 8/e, and runs pins 1 and 3 of the other 8/e connector to pin 3 (GND) on the power controller, and pin 2 on the 8/e connector to pin 1 on the power controller. That's easier in a way, but you'd have to pay attention to which is pin 1 and which is pin 3.

But yours is just 3 wires wired straight through, right? That would be the newer power bus -- perhaps PDP-11 or the like.

Vince​

Yes, it's 3 pins straight through. Probably for an 11, but I thought it would also work as
is for an 8. Since it won't without changing it I will just leave it alone. I don't use the
system that much that I have to worry. I just thought it would be a plug in thing and
just work.