Space Invaders Volume Adjustment

Walkamo

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Hi Everyone,

I recently purchased a Space Invaders that did not have any sound. I replaced some of the diodes on the power supply board and now I have sound, however it sounds like some of the sounds a distorted (too loud)..

I am looking at the owner's manual and it shows that 8 different pots are on the PCB and each one adjusts the a different sound..

The problem is that I cannot find these pots on any of the PCB (3 of them)..

There are two game boards and one power supply PCB...

Can anyone shed any light on this?

thanks,

Chris
 
It probably doesn't help since mine is "Part II", and a cocktail, but the row of white "knobs" in the pic along the left side of the board are where mine are.
 

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No, there is only one volume control pot and it is on the motherboard.
 
Chances are you need a new chip for that sound. I'm not sure if thats one of LM3900s or not. It may be bad and way louder than the rest.
 
Oooops, I should have said daughterboard/sound board but you found it anyway. I have the same problem with SI. The bass sound is very distorted and much louder than the others. It also doesn't seem to be changing in pitch, just an awful distorted thump. It's incredibly bad when you are down to the last invader or two. I'm fixing the 18V section of my power supply to see if it fixes the problem, and then moving on to the daughterboard.
 
Oooops, I should have said daughterboard/sound board but you found it anyway. I have the same problem with SI. The bass sound is very distorted and much louder than the others. It also doesn't seem to be changing in pitch, just an awful distorted thump. It's incredibly bad when you are down to the last invader or two. I'm fixing the 18V section of my power supply to see if it fixes the problem, and then moving on to the daughterboard.

Thanks for the PM... I will keep working on it as well....

Chris
 
Well, mine was indeed the power supply. I replaced all 4 of the A14 diodes with 1N4007s and the 1000MF 35V electrolytic cap in the little sound voltage circuit area below the connector jack. I left the 1N4004 alone. One of the A14s was bad and one of the leads from the cap was coming loose from the end of the cap. Now all the sounds are great. I hope this will fix yours too. Measure the audio voltage like it shows here.
 
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