Tech:Asteroids

Gang,
   Anyone ever work on an asteroids board that worked fine, passed all self
tests, plays
ok. But, in test mode the cross hatch pattern in the background is missing,
and in play mode
the customer stated some vectors were still being drawn when it shouldn't,
(Monitor
brightness was ok), couldn't tell what was missing/there myself on the
scope, looked ok to me.
I guess its time to build up the bw xy monitor project that I keep putting
off...

So, I've checked the outputs on that dac's expecting that maybe they were
being clipped,
but the dac outputs reflect the missing crosshatch pattern so I'm ruling out
the dacs. Kinda
got me stumped, I did notice that in DAX10 (load 10 output from the ls157
or the state machine if I remember right) seems to be pulled low, but I've
replaced the components that are driven and no go, Isolation of that line
puts the game into watchdog as the state machine stops. So, I just assuming
that I'm not seeing the output
on my analog scope fast enough.

Any ideas ?
Thanks
TomW
Received on Fri Feb 12 09:26:00 1999