Re: Where to start on Missile Command PCB repair

Hey Scott,

I have checked the voltages at the test points, I've gettin +5.02, -5.2 and
+ 11.75. I also check across the ram and I got those same readings as well,
so for the power going to the ram and EPROMs is at least correct.

I 'm going to be setting up an Amiga monitor I have tonight and I think I
know where a spare wiring harness is and I'm going to get this all setup on
my work bench to work on it.

I need to find my logic probe, I know I have it, I just have to get my
hands on it! The joys of moving into a house!

-Grant

On Fri, Nov 1, 2013 at 10:01 AM, Scott Zeiser <scott@zeiser.org> wrote:

> Digikey is fine (shipping is cheap for small orders), but 74xx stuff is
> getting harder to find.
>
> I use Futurlec (http://www.futurlec.com) or Unicorn (
> http://www.unicornelectronics.com) for that type of stuff. They're so
> cheap, I just buy small quantities of a variety of chips and keep stuff in
> stock so I have it on hand for repairs.
>
> Regarding this repair, have you checked voltages at all the test points
> (the small rings) on the board? Working on Atari boards is great because
> their engineers made it so convenient to diagnose and trace problems, and
> the single large board design is easy to work on. You need to follow your
> schematic, follow the popcorn trail to find out where your voltages -- or
> signals -- stop. Your logic probe absolutely would really come in handy
> here... It's possible the CPU is bad, but the crystal being bad seems
> unlikely. But again, your schematic with your handy $10 logic probe will
> tell you this stuff in 5 seconds flat...
>
> Never used a CatBox, and I'd like to someday, but a part of me says that
> will take all the fun out of it. :-)
>
> ------------------------------
> *From:* Grant Thienemann <grant.thienemann@gmail.com>
> *To:* rasterlist <rasterlist@vectorlist.org>
> *Sent:* Friday, November 1, 2013 9:27 AM
> *Subject:* Re: RASTER: Where to start on Missile Command PCB repair
>
> Hey Kevin,
>
> Thank you for the information! I've never used Jameco before, I've always
> used digikey.
>
> -Grant
>
>
> On Fri, Nov 1, 2013 at 9:26 AM, Kevin Moore <talon.k@gmail.com> wrote:
>
> 74S00
>
> http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_676959_-1
>
>
>
> On Fri, Nov 1, 2013 at 8:24 AM, Grant Thienemann <
> grant.thienemann@gmail.com> wrote:
>
> Ok lets say you have a 74S00, which is for speed, can you replace that
> with a 74F00?
>
>
> On Fri, Nov 1, 2013 at 9:17 AM, Grant Thienemann <
> grant.thienemann@gmail.com> wrote:
>
> Hey Rodger,
>
> Thank you for the information. I'm looking at wikipedia now about the 74XX
> series chips, which would be the default standard when looking to replace a
> 7400, or 7404 etc, would that be HTC?
>
> Thanks
> Grant
>
>
> On Fri, Nov 1, 2013 at 9:08 AM, Rodger Boots <rlboots2@gmail.com> wrote:
>
> Close. HCT is closer. Either should work.
> On Nov 1, 2013 7:52 AM, "Grant Thienemann" <grant.thienemann@gmail.com>
> wrote:
>
> Ok not to keep getting off topic, but as this is related to the Missile
> Command repair, I'm going to ask. When I look for 74191 I can't find
> anything on Digikey, etc, but when I search for 74HC191 it comes up, is
> that the same thing?
>
>
> On Fri, Nov 1, 2013 at 8:42 AM, <solarfox@triluminary.net> wrote:
>
> On Fri, 1 Nov 2013 00:35:07 -0400, you wrote:
>
> >So I can generally replace a 7404 with a 74LS04 without any problems?
>
> *Normally*, yes, but there *are* cases where you can run into problems. The
> switching speed of 74LS-series parts isn't *quite* identical to standard
> 7400-series; the propagation delays of a 7404 vs. a 74LS04, for example:
>
> -------- 7404 -------- ------- 74LS04 -------
> tPLH 12ns (typ) 22ns (max) 9ns (typ) 15ns (max)
> tPHL 8ns (typ) 15ns (max) 10ns (typ) 15ns (max)
>
> (Source: a very dog-eared and well-used copy of "The TTL Data Book, vol.2",
> Texas Instruments, 1985)
>
> The difference is, admittedly, pretty small, but it can add up when you've
> got signals flowing through a bunch of different gates, or when you've got
> a more complex chip (such as the 74191). So, depending on the circuit in
> question, there's a small (but non-zero) chance that you *could* end up
> with a "race" condition by swapping a 74LS part into a circuit full of
> 7400-series chips.
> --------------------------------------------------------------------------
> "I thought I told you to look after him!"
>
> "He'll be all right; he's a Time Lord."
>
> "That's just what they're _called_; it doesn't mean he actually knows what
> he's _doing!_"
> --------------------------------------------------------------------------
> solarfox@triluminary.net (Gary Akins jr.)
> --------------------------------------------------------------------------
>
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Received on Fri Nov 1 10:10:29 2013