Re: Star Wars Tie fighter issues

Had a Pole Position that would run at 4.5 but not higher, ended up just
running at 4.5.

If you had a fast enough digital scope you could probably find a glitch or
timing problem somewhere, but NOT on the lines you're looking at. Adding
the tester is slowing the transition of those lines enough. 100 pF
capacities to ground would do the same.

Check any ICs that have been replaced and make sure they're the correct
parts---not something like a 7400 being replaced with a 74LS00 for
example. Different family = different timing.
On Aug 22, 2012 9:41 AM, "Kevin Moore" <talon.k@gmail.com> wrote:

> Not sure this went out on the list yesterday. I was having some issues..
>
> Anyways, back to my previous posts on the Tie fighter issues.
>
> I got some time to sit with it, and found something interesting which I'm
> not sure what to make of. I started using my bug trap to look for issues,
> and when I put it on 6h part of the matrix processor counter the problem
> goes away. Its an ls191 I didn't see any fault light come up on the bug
> trap but went ahead and replaced. The original ls191 checked OK and the
> problem still occurs. It will go away if I put the bug trap on. So I
> started checking other chips that had db0 and db1 coming out. I piggybacked
> the ls244 on 4j the problem went away, so I replaced it and check again.
> Problem still present. If I piggy back the ls244 again no problem.
>
> The only things that are common between the two chips are db0 and db1 so I
> believe there is a problem somewhere on the DB buss.
>
> Another observation. The problem doesn't occur when the +5 is lower than
> 5, 4.9 seems to be just fine. But 5.04 no good.
>
> Is there an easy way of finding out which chip doesn't like above +5 or
> should I just run it at lower than normal +5 ?
>
> Kevin
>
>
>

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Received on Wed Aug 22 10:57:47 2012