Asteroids Distortion

jimk

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I have an Asteroids 04 board that is given me trouble. It's playable, but the graphics are slanted. Any suggestions where to start? (*I don't have access to an oscope at the moment.)



Thanks
 
whenever get a new to me ASTEROIDS (well now its every game i get), i replace every electrolytic capacitor i can lay my hands on.

while all that is out, laying on my static free mat, i reflow all the cold solder joints i can find. then i test and see whats what (sometimes HERE i get into replacing transistors, resistors, etc. if they look like they got hot and test bad and cooked the PCB)

that giant big blue capacitor there on the bottom, when they go bad, can cause all kinds of screwy problems. it needs to be changed anyway so i dont get mad if that doesnt fix the current problem.
 
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Here are two shots of the test screen.



What do you think? I'll also look into replacing a few caps.

Thanks
 
You are correct, but it's been Space duel boards lately.

So looking at the pictures, it's in the y circuit correct?

So that would be J9,H9,or F9?
 
Finally got my chip order and some time to try it out. I replaced the 7479 at F8 and the picture is much improved. Only thing left is some ripple in the graphics. Any ideas?



Asteroids Board version - 04

Thanks.
 
that could be any number of things - ranging from power ripple to a bad DAC

how noticeable is it in game play ?
 
It's noticeable mainly on the asteroids as they track through the screen.
 
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