Space Invaders II Sound issue

[Farmboss]

Hi everyone.  I am struggling with my space invaders Deluxe.  I followed the instructions I found here.  http://www.brentradio.com/SpaceInvadersSoundRepair.htm. 

I replaced all caps on the sound board, changed the  lm3900 at M5 and replaced both the 74174 at E5 and the 7417 at F5.

I am still getting a very high pitched scream when I coin up.  The sound exists throughout the entire game.  Also I don't have any saucer explosion sound.  I am stumped at what is going on.   Any help would be appreciated.  Thank you

[TheGuru]

Space Invaders uses multiple LM3900's (from memory about 6 or 7).
Try replacing all of them. That will likely fix your saucer sound too.
Otherwise you have a logic fault. Not surprising really for a game that's nearly 40 years old ;-)
There's not that many logic chips, you could just change all of them in shotgun style and as a side effect it'll bullet-proof your board for the future too.
Be sure to replace the logic chips with new parts and test them in an EPROM programmer to make sure they really are good.
Also use machine pin sockets, not cheap dual-wipe sockets.... Space Invaders deserves the best ;-)