Sound problem in MVS Board 1 slot

[Jarryson]

Hi all, i have an issue with a MVS MV1F, 1 slot.

Sounds, in this case FX, effects, voices, are distorted, i dont know how to explain it. Music works fine.

I have repaired many mvs boards but i cant find the problem in this one. Traces between ram (6116), SM1 , Neo-D0, z80, Y2610 are tested, following the jamma nation diagrams.

I have replaced the Y2610 and nothing changed. I have been 2 weeks with this board and I dont know how to continue, any idea?

Tested Neo Diag bios too, I can see Z80 expected C3, Actual: 00, but I am not using the M1 eprom so this error maybe I can skip it.

Video:
https://www.dropbox.com/scl/fo/6kbrjjth9u2ml6dybx1dn/h?rlkey=thq7garkp9ccpbrp08yyaft0j&dl=0

 

[wesprice]

The neogeo eyecatch sound is fine which means your yamaha opn chip is probably fine.

the data for the speech / sound etc comes from the VROM chips on the prog pcb. I've repaired a few boards with very similar distortion and they were caused by a broken trace on one of the sound datalines from the prog cart to wherever they go to.

Just to make sure you have tried something other than samurai shodown right to verify that it isn't a bad cart? I had a KOF94 cart that was all messed up but it was a dying V2 maskrom.

It will probably take an hour or so but i'd start by probing the cart slot for the progboard and make sure the datalines are intact to wherever they go, some of the traces run under the cart connector so are difficult to visually inspect, the schmatics are easily found online so it shouldnt take too long.

 

[Jarryson]

Hi, I will search the slot diagrams. This game works perfect in my other mvs boards, tested in 4 different boards (mv1f, mv1fz, mv1b, mv1A).

 

[BIG BEAR]

Hi, I will search the slot diagrams. This game works perfect in my other mvs boards, tested in 4 different boards (mv1f, mv1fz, mv1b, mv1A).

Replace the audio caps.
BB

 

[Jarryson]

Hi big bear, I am maybe the only person who thinks replace caps when they are not swollen is a waste of time. I dont know, maybe you are right, in fact I have read all the channelmaniac repair logs and he always replace caps, maybe this is the way...

 

[Jarryson]

I have replaced many caps and nothing changed. Socket installed in 6116 ram and SM1 and nothing changed. Traces betwen Y2610 and cart socket seems to be ok, I dont know how to continue...

 

[BIG BEAR]

I have replaced many caps and nothing changed. Socket installed in 6116 ram and SM1 and nothing changed. Traces betwen Y2610 and cart socket seems to be ok, I dont know how to continue...

You verified all the traces of the 2610..you replaced the caps,correct?
Replace the amp.
BTW I've replaced certain caps in the audio section before which has solved the problem you have now so don't rule out replacing them in the future.
BB

 

[Jarryson]

Yes, 2610 traces are tested with every sound IC and cart socket. I only replaced some caps, not all.