Isn't space zap an MCR game, or was it before that system? It sure looks like MCR but I don't see it listed in the MCR FAQ and can't find a reference that it is MCR. Trying to figure out the sound problem...just curious.
In MAME, it uses the Astrocade driver, which is also used by Gorf, Wizard of Wor, Robby Roto, Professor Pac-Man, and Sea Wolf II (and a couple others). So I would guess it's Bally Astrocade hardware.
Wow, yes that's what I was thinking but I couldn't get MCR out of my head. The pcbs are in the cage just like gorf, wow, etc. Thanks for clearing the mental block.
Depending on the issues....check the amp board (the small one with the volumn pot)....or the game board (the board in the cage with all the connectors on it).
The sound issue can also be on the main power supply card...
On the bottom of the card pictured above, right about in the middle(below the set of two smaller capacitors) there is a diode that could be stopping your sound dead. You can use a 1N4007 to replace it and see.
On two of my power supply cards that diode has broke in half when I put a screw driver underneath it and pried up just a little.