Thought I'd share an odd Galaga repair with y'all since it's not on the 2 main Galaga troubleshooting web pages...
Symptom: Player and enemy graphics are tilted 45 degrees. Player explosions are divided into 4 pieces. Enemy explosions are represented by the number 20 over the number 31. If the enemy is tilted left the numbers are upside down. If the enemy is tilted to the right the numbers are right side up.
Solution: Replace bad 74LS153 at location 1B on the video board.
The inputs were good but the outputs were stuck low with very narrow racing pulses. The outputs of this chip drive pins 1 and 2 of the graphics ROMs.
Enjoy!
Symptom: Player and enemy graphics are tilted 45 degrees. Player explosions are divided into 4 pieces. Enemy explosions are represented by the number 20 over the number 31. If the enemy is tilted left the numbers are upside down. If the enemy is tilted to the right the numbers are right side up.
Solution: Replace bad 74LS153 at location 1B on the video board.
The inputs were good but the outputs were stuck low with very narrow racing pulses. The outputs of this chip drive pins 1 and 2 of the graphics ROMs.
Enjoy!
