Tuesday, May 14, 2019

Backplane "Mapper" (DG Nova, DCC D-116 & Entrex 480/Nixdorf 620)

This is a crazy project that I'm just muddling my way through with sheer ignorance and determination.

I want to test every connection in every slot of the backplane of Dominique's Entrex 480/Nixdorf 620, since it is the only known surviving system of its kind in existence, and then reverse engineer the thing from the center outward.

So, here's the backplane "adapter board" design...
Click to download the Gerber files

And here's my schematic on how I'm going to use an Arduino (I know...can't I do better??!!!) to test each and every connection in each slot I plug the set into.

Yes, there are so many things wrong with it...I know...
Click to see full-size schematic

I even asked for help here on Upwork:
https://www.upwork.com/jobs/~017df3e1f95d130afa

But I haven't hired anyone yet...

Here's the text from the job post...
-------------------------------------------------------------

This hand-drawn image of a circuit is a rough draft of what will become an "oversized" Arduino shield.

You will want to right-click and download this, because it is a large image, high resolution, with high detail, and will require a lot of zooming in.

http://bit.ly/2G7kaEo

This circuit is intended to use 12 Fairchild ADG732 chips, and 4 Texas Instrument CD54HC251 chips. (Yes, I know that the ADG732 is surface mount and the CD54HC251 is through-hole, we'll keep it that way for now).

This rough-draft version of the circuit makes certain assumptions that you should fill in, such as proper chip grounding pins, chip source voltage "power" connectivity. It may also contain some mistakes or logic errors.

I am fully open to suggestions here.

However, the job is intended to be straightforward. Create production-ready Gerber files from this rough schematic.

I am going to leave the board layout to your imagination, creativity, and "best judgement" (even though I will, of course, be the final judge of how it needs to be...but I want to see your ideas in action).

So, there you go. I've done all of the "thinking" work for design/concept, but I need your refinement, and Gerber building skills.

So, are you up for this challenge?

Datasheets for the chips I chose to use are the

ADG732

and the

CD54HC251

or the similarly equivalent more modern MM74HC251

Thanks, and good luck.

My internal job notes:
April 8 Post
May 22nd Post

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