Quoted from ForceFlow:
Sound boards can be black boxes since they aren't documented nearly as well as the rest of the boardset.
You'll have to use the schematics to figure out what the edge connector pins are for so you can verify the voltages. It's also a good idea to check the diodes, make sure the nuts for the regulator are tight, and clean off the edge connector contacts with a pink rubber eraser.
Unfortunately, this particular board has a fatal flaw in which the two unobtainable chips are known to go bad, so like the MPU, it tends to be a throwaway board more often than not.
There is a MIOT adapter board you can use in place of the bad chips: https://coinop.mally.eu/produkt.php?bestellnr=101647&details=1
Or, you can replace the whole thing with an aftermarket board:
https://www.flippp.fr/pifx1.php (from France directly, or US suppliers like bigdaddy-enterprises.com sometimes carry them)
Very cool, First I have heard about the system 1 sound replacement board. This is a guy that is known to straighten out manufactures short comings. I wonder if he fixed the Genie "L" to have more than one sound for almost everything you hit when playing the game? Its so lame I go with a chime unit when I shop a Genie, seems to match the theme better too.