No sound on MVF4 , top board faulty

[jfs9999]

Hi everybody.

Sound stop working suddenly on my neogeo mvs 4 slots .
Sound is good in test mode, but nothing in game.

I ve swapped the top board with a working slot to find that the issue is the Top board.

Now i need your help. Everything looks good on the top board.

We have : 2x caps, 4x neo-g0,6x neo-244, 5x neo-253 and 2 x TTL ( 74f153 and 74aS04n).

I don't know what i need to replace, perhaps the 2 TTL ?

Thank for your advise...

 

[jfs9999]

Top board picture :

 

[jfs9999]

Do you know where i can find schematic for mvf4 (newest) please ?

 

[jfs9999]

Remplaced the 2 TTL (74f153 and 74aS04n) without success...i don't know what to do now...