Audio problem with MVS MV1F

[InitialNik]

Hi everybody,

I have a problem with a MV1F board.

When I received it, it hadnt any sound...so I started checking traces...I repaired 4 traces from Z80 to Yamaha 2610 and 2 traces from Neo D0 to Z80 I think.

I mounted Z80, Sm1, Ram 6116 in sockets and I replaced them by other working IC. I add: NEO-C1 is changed too, because 2 buttons were pressed. Yamaha 2610 is changed too by other working.
All new chips mounted are from other working board.

Now I have sound, (never had z80 error or similar) but there are missing sounds, for example: when I insert coins, no sound. In samurai shodown when select character, no sound when you move to select character.

And sometimes, for example, I turn off the board and I wait 5-6 hours...I turn on again and there isnt any sound, totally mute.

I cant understand what happening here, i can accept some missing sounds, but why sound is mute sometimes ?

Can anyone help me?

Remember, is a MV1F single slot.

I have tested with neo diagbios but I dont have M1 rom to test sound, when i do the z80 test I get a Z80 Error Expected: C3 - Actual: 00.

Thanks in advance.

EDIT: I Have checked traces between Z80 and Cart Slot + Y2610 to cart slot and everything OK. Traces between audio chip are ok. Only chip i havent changed is Neo-D0 becuause is in good condition.

 

[Ryoandr]

Coin sound and cursor move are SSG sounds generated directly by YM2610, pin 27, check everything on that line.
other sounds are sent on 4 data lines, that mostly run along with the analog SSG out trace, to the YM3016. Check for bad things on these lines, pins 29, 30, 31, 64.
your YM3016 or some components around might be dying.

 

[InitialNik]

Hi, thanks for reply, i will check again what you say, but I think all traces were checked, and Y2610 is from other working board where I heard the coin sound, but in this mvs not coin sound.

 

[InitialNik]

Coin sound and cursor move are SSG sounds generated directly by YM2610, pin 27, check everything on that line.
other sounds are sent on 4 data lines, that mostly run along with the analog SSG out trace, to the YM3016. Check for bad things on these lines, pins 29, 30, 31, 64.
your YM3016 or some components around might be dying.

You were right. Pin 27 was not connected, and I thought I had checked everything. I don't know how to thank you for this, thank you so much. I had no hope that anyone would answer me.