Re: BU409 -> signature analysis

What I usually run into is good signatures for a while - so I know the setup is right,
but then once I run into a bad signature I have a hard time finding where it's coming
from. In other words - the output is bad but so are the inputs, go to the next chip
same thing, and so on and so forth until it kind of becomes a mouse maze.

What I find even more confusing, and maybe someone can explain. I'll hook up a
working game board, usually Star Castle, and the main signatures are good so I know
everything is hooked up right. But at some point I'll find a signature that doesn't
match somewhere deep in the circuitry. So even though the game is working fine and
*most* of the signatures are good - I'll usually find a bad one somewhere.

Kinda frustrating.

Matt

>
>
> You use it to find a bad sig., and then backtrack until you find a
> good sig. The point(s) at which the sig. goes bad is/are your bad
> chip(s). Where to find the bad sig is kind of random, but for a broken
> board, you should be able to find a bad sig. without much effort -- start
> at the output(s) of the ALUs or memory or something like that.
>
> If you are finding that you have no good sigs or no bad sigs, I'll
> need to think about that case some more......No bad sigs implies no
> problem, while no good sigs implies a setup problem or something like
> that.
>
> Joe
>
> ---------------------------------------------------------------------------
> ** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
> ** message body to vectorlist-request@synthcom.com. Please direct other
> ** questions, comments, or problems to neil@synthcom.com.

---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Tue Nov 28 19:15:31 2000