[vcf-midatlantic] Schematic work needed

systems_glitch systems.glitch at gmail.com
Wed Aug 29 08:22:20 EDT 2018

I'd had the ISA card in the shop for a while and didn't get around to
mapping it out. I've explained to Evan that it's not a trivial process.

I offered to depopulate the board and send it off to Mile High Test for a
scan + conversion to Gerbers, which are guaranteed to be 100% accurate, but
that costs around $200-250. It's the same process I've used to reproduce
various Ohio Scientific and S-100 boards.


On Wed, Aug 29, 2018 at 2:58 AM RETRO Innovations via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> On 8/29/2018 1:15 AM, Evan Koblentz via vcf-midatlantic wrote:
> > I need someone to make two (relatively simple) schematics for me. One
> > is the IBM card for the Lego kit, and one is the Lego interface box.
> >
> > Here is one side of the IBM card:
> > http://snarc.net/lego_ibm_1.jpg
> >
> > Here is the other side:
> > http://snarc.net/lego_ibm_2.jpg
> >
> > Here's a picture of the top of the interface board:
> >
> http://4.bp.blogspot.com/-DGOlTkGXj_Q/U8-T2uBG5iI/AAAAAAAAATY/7ra6gVkSKg8/s1600/LEGO_ControllerBoard_Top.jpg
> >
> >
> > Here's the bottom of the interface board:
> >
> http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.html
> >
> >
> > Here's a document Dan R. made of the board a year or two ago:
> > http://snarc.net/9750.png
> >
> > Now here is the catch..... I absolutely MUST have a complete, perfect,
> > finished schematic of the IBM card and the interface board by a week
> > before Maker Faire -- so let's say the deadline is Friday, Sept. 14.
> Do you have a backup plan?  I say that because I professionally feel
> that creating a working and tested schematic within your timeline is
> going to be nearly impossible.
>   * The first board is two sided, and those typically need to be
>     unsoldered to ensure all traces under the ICs have been mapped. One
>     can try to use a multi-meter, but there are pitfalls
>   * Even if the schematic is doable, there's no way to truly ensure it's
>     perfect unless one make a spin of the PCB, populates it, and tests
>     it.  unless one wants to spend $250.00, it takes about 2 weeks to
>     spin a PCB.
>   * Though the other board looks to be single sided, all of the items on
>     the board must be described and validated.  The toroids in the
>     center and right seem particularly problematic, as one needs to
>     determine the uH, turns, and such of the items in order to be
>     perfect.  As well, those TO-220 transistors (or maybe they are FETs)
>     sandwiched in between the connectors need to be desoldered or
>     somehow moved so the markings can be read.  The LEDs need to be
>     scoped to determine their mA rating, etc.
> I'm not trying to rain on the parade, but I do want to inject some
> realism into the request timeline.  Doing such a reverse engineer will
> probably take a month or so, assuming someone squeezes it into their
> normal workflow and they do this regularly.
> Someone already made a schematic of the Apple II card:
> >
> http://lukazi.blogspot.com/2014/07/lego-legos-first-programmable-product.html
> >
> Regrettably, it looks like the Apple uses a different schematic
> completely (It uses a VIA instead of the IBM PC discrete TTL) and so
> this schematic will not help.
> Jim
> --
> RETRO Innovations, Contemporary Gear for Classic Systems
> www.go4retro.com
> store.go4retro.com

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