Got a mostly working SI Deluxe PCB recently. Only problems were in the sounds, there was a general distored noise during game play, fire sound was working but sounds wrong, Base explode sounds was missing and finally the Invaders hit sound was missing.
Symptom:
General noise as soon as a game starts, just a loud general hiss all the time. I suspected a problem with the noise generation circuit because the Missile sound was wrong and the Base Explode sound was also missing.
Fix:
Socketed the 4006 and 4030 and removed them. The annoying noise was gone, replaced both of them but then the racket returned so I looked instead to the 3900 op amp at K3-4. Replaced it and the noise was gone and the Base explode sound was back.
Symptom:
Fire sound was a still strange whine even after fixing the base explode and noise issue.
Fix:
As I'd confirmed the noise circuit was fine I looked at the op amp where the noise is used for the missile fire sound, this is the 3900 at P4. Replaced it and the missile fire sound is working again.
Symptom:
Invader hit sound is missing.
Fix:
Again another bad 3900. This time the one at K4, replaced it and the invaders die with that satisfying sound as they should.
DanP.
Symptom:
General noise as soon as a game starts, just a loud general hiss all the time. I suspected a problem with the noise generation circuit because the Missile sound was wrong and the Base Explode sound was also missing.
Fix:
Socketed the 4006 and 4030 and removed them. The annoying noise was gone, replaced both of them but then the racket returned so I looked instead to the 3900 op amp at K3-4. Replaced it and the noise was gone and the Base explode sound was back.
Symptom:
Fire sound was a still strange whine even after fixing the base explode and noise issue.
Fix:
As I'd confirmed the noise circuit was fine I looked at the op amp where the noise is used for the missile fire sound, this is the 3900 at P4. Replaced it and the missile fire sound is working again.
Symptom:
Invader hit sound is missing.
Fix:
Again another bad 3900. This time the one at K4, replaced it and the invaders die with that satisfying sound as they should.
DanP.
