What about your rectifier board in the cabinet? Make sure all of the readings there are good first. Follow the power from the rectifier through the game until it reaches the sound board. I don't have a schematic handy to see if the power goes from the rectifier board to the solenoid driver board and then to the sound board or if it is just a straight shot and the sound board creates its voltages from what it supplied.

Check the connectors and that ribbon cable that joins the two boards together. Make sure there are no cold solder joints.

In my experience Xenon's rectifier board usually needs to be rebuilt as it has a lot of demand on it.

No sound at all can be because any number of things.
- speaker connected properly and working?
- volume potmeter in door working and connected (also check the connector for connecting the coin door)
- potmeters on pcb working?
- amplifier ic ok?

Your 5V for the vocalizer should only be for the voices, if you have no sound at all I'm thinking something else is also wrong. To get this 5V the input connector (or the one on the soundsplus board) probably needs resoldering or a proper connected wire.

When you have a look at the schematics it says: 0VDC without sound, 2.5VDC +/- 1V with sound.
Edit: TP4 is for the VMA, so I think the processor is trying to produce sound as it should if you measure 2V.

What do you measure on TP6, U8 and U9 (and compare them to the voltages in the schematic).

_{Post edited by Richard_BoK : TP4 is not a sound signal, but VMA}

do you have an 'AS 2518-57' vocal module and 'AS 2518-56 sounds plus module? and do you have schematics and a parts list?