[Article 6307]Troubleshooting Asteroids PCB (3)

Ok, I spent a bit of time to understand what happened.

I could solve the problem number 1, now all the screen is used. I just replaced a 74191 in F9 position. UNMDACY11 was always low.

 

IMG_20170210_023349

 

Now I’ve one problem only. The game starts, the TEST doesn’t show anything wrong but what I see is very strange. All DIP SWITCHES were in the same position so the language is SPANISH with 2 COINS PER 1 GAMES. As you can see the problem affects some asteroids (just one on the left ) and the alphanumeric messages.

 

asteroidspcb004

zoomed “2 FICHAS 1 JUEGO”

asteroidspcb005

as you can see the message moves downwards and “ASTEROIDS BY ATARI” is not shown.

I’m quite blocked now because I checked all Y circuits from the output to the VECTOR ADDRESS COUNTERS…

ROMs have been checked and vector RAMs replaced.