Re: Where to start on Missile Command PCB repair

7400
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_48979_-1

7404
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_49040_-1

74191
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=74191&langId=-1&productId=49904&storeId=10001&ddkey=http:StoreCatalogDrillDownView

On Fri, Nov 1, 2013 at 8:17 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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>>>> chris@westnet.com
>>>>
>>>
>>>
>

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Received on Fri Nov 1 09:25:37 2013