Re[2]: Need help with Joust graphics output problem

All the socketed chips (RAM, decoders, and CPU) in this board were moved
from a working board so I *HOPE* it's not a problem with the
RAMs! Actually I had to put the old CPU back because the known working CPU
gave me intermittent RAM errors! Weird.

I socketed the 7474 (D flip-flop at 3A on ROM board) that generates the
screen control signal and drove the signal manually to eliminate the 74166s
and 74257 at the bottom of the CPU 2 schematic. The result was a flipped
screen but I still have the same garbled graphics. :-(

Since the problem is all over the screen (not in bands horizontally or
vertically), is there any place I should focus or can ignore?

Thanks!

At 05:43 AM 2/28/2004, you wrote:

>-----Original Message-----
>From: Steven Winslow <winslow@earthlink.net>
>To: rasterlist@vectorlist.org
>Date: Fri, 27 Feb 2004 18:31:15 -0800
>Subject: Re: RASTER: Need help with Joust graphics output problem
>
> >
> > Frank !
> >
> > Looks like a screen I had not too long ago on my Joust that had bad RAM
> (4116).
> >
> > Surprised it didn't give you a RAM error after the test...
> >
> > Steve
> >
>
>yea, williams stuff cant do a full ram test,
>i'v seen the problem with defender.
>do the burned-fingers test,
>then move the chips around and do a new test.
>
>it's a specific set of rams, but i cant remember the locations - it was
>mentioned in a service bulletin.
>
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--
Franklin Bowen (Franklin@Bowen.net)
http://fmbbowen.com:39353 
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