Re: Midway Space Invaders sound problems

Alex Yeckley wrote:

> Although your 4006 may be bad, that alone won't cause what you've described.
> You've essentially got a gate "stuck open". You might try isolating which
> sound channel has the problem by pulling the various summation resistors.
> Hopefully you've got an oscilloscope.

Unfortunately I don't have an oscilloscope. I do know that if I remove
the LM3900's that drive the missle sound, the constant high pitch sound
goes away. I'll try testing each resistor in that section and see what
turns up.

> Yes, or possibly the 4030. I can spare a couple of 4006's - I'll try to get
> a couple in the mail on Tuesday.

Thanks. I appreciate it.

> That's the sound enable line kicking in, and about 80% of them do that. I
> haven't studied the other 20% to find out why those don't. You might be
> able to solve the problem by adding a capacitor to ease the edge of the
> enable signal (active low going into the preamp), since it's essentially
> analog.

Interesting. Does this mean the pop sound was present when SI first
came out? I can't recall if I heard that pop sound or not when I played
it back in the day at various arcades.

Rodney

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Received on Mon Oct 25 15:39:29 2004