Mounting the KC8A Programmer's Console?

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Bob Armstrong

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May 24, 2020, 2:50:30 PM5/24/20
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How is the KC8A (the PDP-8/A push button programmer's console) supposed to be attached mechanically to a BA8C chassis? This is purely a mechanical question - electrically my KC8A works fine. I suspect that I'm missing some kind of mounting bracket or something, but I can't find any pictures or even DEC maintenance prints that show the exact details.

I also have an 11/04 and the console for that, which is physically nearly identical to the KC8A, bolts neatly to the front of the BA11-K. That works great, but the BA11-K has slides and you access the cards from the top, where as the BA8C has no slides and you have to access the cards from the front. That means that however the KC8A is mounted it has to be fairly easy to remove.

Thanks!

Vincent Slyngstad

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May 24, 2020, 4:07:49 PM5/24/20
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On 5/24/2020 11:50 AM, Bob Armstrong wrote:
> How is the KC8A (the PDP-8/A push button programmer's console) supposed to be attached mechanically to a BA8C chassis? This is purely a mechanical question - electrically my KC8A works fine. I suspect that I'm missing some kind of mounting bracket or something, but I can't find any pictures or even DEC maintenance prints that show the exact details.

This was recently discussed on VCForum:
http://www.vcfed.org/forum/showthread.php?74718-Adding-a-Programmer-s-Console-to-a-PDP-8-a

The short answer is that there are some metal bits that screw to the
rack, rather than those black plastic post thingies.

The metal bits have a captive nut. The Programmer's panel has kept
bolts/screws inside that tighten into the nuts to hold the panel on.
The tightening is done with an allen wrench and a hole, IIRC, like
bathroom towel bar :-).

Vince


Bob Armstrong

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May 24, 2020, 6:27:48 PM5/24/20
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On Sunday, May 24, 2020 at 1:07:49 PM UTC-7, Vincent Slyngstad wrote:
> This was recently discussed on VCForum:
> http://www.vcfed.org/forum/showthread.php?74718-Adding-a-Programmer-s-Console-to-a-PDP-8-a

Guess I'd better join that forum :) It won't let me see the pictures while I'm waiting for my registration to be processed, but if I understand correctly then my KC8A doesn't have the holes on the lower (downward facing) edge that would hold the captive screws that screw into that bracket. It sounds like somebody else in the discussion had the same problem, so maybe these things went thru a design revision somewhere along the way?

Can't believe that it's intended to mount to those little plastic pop panel ball thingies. Those can barely hold up a blank plastic panel without breaking.

Speaking of the pop panel thingies, they have a threaded insert in the center. I may just drill a hole on either side of my KC8A so that I can insert a long screw from the front and thread it into that insert. I hate to drill holes in my KC8A, but right now it's just being held on with shipping tape...

Thanks,

Vincent Slyngstad

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May 24, 2020, 7:29:40 PM5/24/20
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On 5/24/2020 3:27 PM, Bob Armstrong wrote:
> On Sunday, May 24, 2020 at 1:07:49 PM UTC-7, Vincent Slyngstad wrote:
>> This was recently discussed on VCForum:
>> http://www.vcfed.org/forum/showthread.php?74718-Adding-a-Programmer-s-Console-to-a-PDP-8-a
>
> Guess I'd better join that forum :) It won't let me see the pictures while I'm waiting for my registration to be processed, but if I understand correctly then my KC8A doesn't have the holes on the lower (downward facing) edge that would hold the captive screws that screw into that bracket. It sounds like somebody else in the discussion had the same problem, so maybe these things went thru a design revision somewhere along the way?

I sent some crappy cell phone photos of mine, though VCForum may approve
your membership before you get them.

> Can't believe that it's intended to mount to those little plastic pop panel ball thingies. Those can barely hold up a blank plastic panel without breaking.

Agreed, that wouldn't work.

> Speaking of the pop panel thingies, they have a threaded insert in the center. I may just drill a hole on either side of my KC8A so that I can insert a long screw from the front and thread it into that insert. I hate to drill holes in my KC8A, but right now it's just being held on with shipping tape...

Ouch!

I also drew up, but have not tested, a simple 3D triangular solid with
some tabs on it. This would be 3D printed, then used instead of the
bent bar stock with the kept nut. Instead, you'd dill and tap the
plastic where the screw was to enter. (The tabs have holes for the
screws that mount it to the box/rack.)

Vince

m. thompson

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May 25, 2020, 11:09:39 AM5/25/20
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There are two mechanical versions of the front panel. The early versions use the standard plastic ball-stud that is used on filler panels. The later versions use a bent metal bracket that screws to the chassis, and then screws hold the front panel to the bracket.

Bob Armstrong

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May 25, 2020, 12:15:22 PM5/25/20
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On Monday, May 25, 2020 at 8:09:39 AM UTC-7, m. thompson wrote:
> There are two mechanical versions of the front panel.

Apparently I have one of the early versions - there are no holes in my panel for the mounting screws described. Those pop panel balls are totally inadequate for the job, and I think I'm going to have to drill some holes in mine.

Anybody have a spare set of brackets they can part with?

Thanks

m. thompson

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May 26, 2020, 9:36:03 AM5/26/20
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I need two sets of the mounting brackets.

Robert

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May 29, 2020, 9:41:55 AM5/29/20
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I confirm Michael's mention of an early and late version of the panel
and fitments, I have an early one with no provision for attaching
metal brackets etc. and it does as you'd noted mount simply onto the
usual nylon ball fittings. I know the history of mine and I remember
the field engineer installing it. It always seemed a bit of a bodged
design with the fans preventing easy access through the H960 frame to
bolt it in.
FWIW mine is AOK on the nylon knobs, fits tight easy on/off the only
reall annoyance is the standard ribbon cables which are too short to
get the panel anywhere useful when youre working on it - I use long PC
ones.


On Mon, 25 May 2020 09:15:21 -0700 (PDT), Bob Armstrong <b...@jfcl.com>
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