Asteroids intermittent explosions

Hey guys,

Here's a good one. I have been seeing alot of failures in the pos cntr section on ast boards lately that result in erratic explosions displayed as a horiz or vert line. Very intermittent. Usually the center 191 cntr ic on each axis is at fault but on one I have had to replace everything from the data latch up to (but not including) the d/a convertor in attempt to isolate the problem on one axis. But the bizarro behavior persists. As a last resort I put in a new vector prom socket and subbed in a different prom (I believe the explosion graphic is pulled from the n/p2 prom) to no avail. I'm out of ideas and int. problems are the worst to track down....especially when you must play the game to see it happen.

Anyone else seen this?

Sidebar note:
Topside solder pads on these older Atari pcb's are getting really grumpy and pulling up with little or no reason to. Especially those without an attached trace. Weak plating on the component side maybe? I dunno, but I'm being EXTREMELY gentle with them (cutting the ic out and removing the pins one at a time) and still have one come loose once in a while. The coated side is much more durable. Just a heads up.

Have a good one
Travis

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