Asteroids bad vectors

[smarty]

Hi All,

My Asteroids has stared playing up again... It failed whilst in attract mode, the vectors on the rocks generally seem to have a small section missing and there are some extra lines being redrawn around objects when they move.

All voltages are spot on,

The game plays fine with exception of the graphics fault.

Test mode:

Gameplay:

Video:

Any pointers where to look please, This board has had a fair few IC's socketed, but none that I have swapped over have made any difference.

Thanks, Mart.

 

[Equites]

In all honesty? It could be a few things.

Did Self-Test report any bad RAM?

I've seen similiar problems caused by a bad 74LS273 Octal Flip-Flip on the VSM section (there are four of them in a bank) on Purity's PCB.

 

[smarty]

Thanks for the reply,

Self test passes OK, I have swapped the RAM's around and that made no difference, Apart from the ROMS & CPU the board has 35 socketed IC's, It's had plenty of work/shot gunning gone on in the past I think.

The 74LS273's you mention have not been touched, I will take a look and see If I can prove their functionality with my logic probe and multi meter.

Cheers, Mart.

 

[VectorGlow]

Working on this board right now - found that pin 14 of the LS161 at location B7 was stuck high - replacing it fixed the test grid fault. However ........ I could never reproduce the in-game fault as seen in the video (before or after the repair).

Also noticed that the asteroid and saucer explosion sounds are dead, so off to fix those soon.
VectorGlow2013-05-04 12:18:05

 

[Equites]

Working on this board right now - found that pin 14 of the LS161 at location B7 was stuck high - replacing it fixed the test grid fault. However ........ I could never reproduce the in-game fault as seen in the video (before or after the repair).

Also noticed that the asteroid and saucer explosion sounds are dead, so off to fix those soon.

Are there any subs for 566?

 

[VectorGlow]

Working on this board right now - found that pin 14 of the LS161 at location B7 was stuck high - replacing it fixed the test grid fault. However ........ I could never reproduce the in-game fault as seen in the video (before or after the repair).

Also noticed that the asteroid and saucer explosion sounds are dead, so off to fix those soon.

Are there any subs for 566?

Not that I'm aware of.

BTW, sound fault now fixed on smarty's Asteroids; dodgy output on pin 2 of the 74LS04 at location L5