Re: Space Invaders Sound question

From: Dave Langley <>
Date: Mon Dec 29 2003 - 09:31:54 EST

At 09:32 am 29 12 2003, you wrote:
>I'm trying to fix a Midway Space Invaders sound board. The invader hit
>sound and saucer hit sound are both a high ring. I've replaced all the
>LM3900's and the 4016 in both circuits.
>I'm thinking both problems are
>On pins 4 and 5 of LM3900's (M5) and (K5) there should be some sort of
>pulse, instead it's just a straight 12v line. Can someone explain to me
>what causes those pulses (when the board is working) and what I can check
>to get my sounds to work properly?

Your Noise generator circuit is not working. This consists of a 4006 (IC
N5) and a 4030 (IC P5).

Dave Langley

** Unsubscribe, subscribe, or view the archives at
** Please direct other questions, comments, or problems to
Received on Mon Dec 29 09:32:01 2003

This archive was generated by hypermail 2.1.8 : Mon Dec 29 2003 - 16:50:01 EST