Re: Where to start on Missile Command PCB repair

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_at_gmail.com> >To: rasterlist <rasterlist_at_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_at_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_at_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_at_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_at_gmail.com> wrote: >>>> >>>>Close.  HCT is closer.  Either should work. >>>>>On Nov 1, 2013 7:52 AM, "Grant Thienemann" <grant.thienemann_at_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_at_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_at_triluminary.net                                  (Gary Akins jr.) >>>>>>>-------------------------------------------------------------------------- >>>>>>> >>>>>>> >>>>>>>--------------------------------------------------------------------------- >>>>>>>** Unsubscribe, subscribe, or view the archives at http://www.vectorlist.org >>>>>>>** Please direct other questions, comments, or problems to chris_at_westnet.com >>>>>>> >>>>>> >>>> >>> >> > > >
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Received on Fri Nov 1 10:01:06 2013