dgersic
New member
I've been reading old messages here on MCR sound problems, but before I break out the board stack again, I wanted to run this by.
This game has all original boards, power supply had battery damage, but that has been repaired.
I get the music from the cheap squeek board ok, on both speakers. I think this confirms that the amplifiers, volume pots, and speakers are ok.
In the Channel Test, 1, 2, and 3, do nothing, 4, 5, and 6 play a tone on the right speaker.
In the Sounds Test, I'm missing:
4. Extra Base
6. Bomb Fall
12. Machine Gun
15. Tire Chirp
16. Tire Slasher
22. Missile Launch
25. Bullet Ricochet
The other sounds all play, but only from the right speaker.
I read in an earlier message that there are two AY-3-8910s responsible for the sound effects, and that one runs channel 1/2/3, the other is channel 4/5/6. So it's a good bet that one of these is dead, or its LM324 pre-amp is bad. Would that account for the missing sounds? Or am I going to be looking for more problems? Should I be hearing sound effects from both speakers?
This game has all original boards, power supply had battery damage, but that has been repaired.
I get the music from the cheap squeek board ok, on both speakers. I think this confirms that the amplifiers, volume pots, and speakers are ok.
In the Channel Test, 1, 2, and 3, do nothing, 4, 5, and 6 play a tone on the right speaker.
In the Sounds Test, I'm missing:
4. Extra Base
6. Bomb Fall
12. Machine Gun
15. Tire Chirp
16. Tire Slasher
22. Missile Launch
25. Bullet Ricochet
The other sounds all play, but only from the right speaker.
I read in an earlier message that there are two AY-3-8910s responsible for the sound effects, and that one runs channel 1/2/3, the other is channel 4/5/6. So it's a good bet that one of these is dead, or its LM324 pre-amp is bad. Would that account for the missing sounds? Or am I going to be looking for more problems? Should I be hearing sound effects from both speakers?

