MV-1C sound issues - garbled sound effects - fixed by channelmaniac

Testocules · Dec 14, 2007

I have a issue that looks very similar to the one described in this thread "Strange 2 Slot sound problems: broken chip?"

I have an MV-1C that I am preparing to consolize. Before I started soldering anything, I thought it would be a good idea to know everything works as expected. I plugged the 1C into the Jamma harness in my cab and I get strange sound distortions and cracking noises.

I tried two different games and both did the same thing to varying degrees. One seemed to do it more than the other, but seemed more than likely tied to the sounds that were being generated by the games than a consistent or rhythmic noise. Not all the sound is distorted either.

So I removed the Neo and I replaced the Jamma harness on to my Killer Instinct 2 board... and the sound is fine again for KI.

When I searched the forums for similar issues, and found that the other thread I mentioned above never had a resolution. I don't care to fix this for use in a cab, I just need stereo off the board for output on the CMVS and I fear the problem could be the sound chip. Anyone have any possible suggestions or know what this problem is?

ttooddddyy · Dec 14, 2007

Have you cleaned the cart and slot connections squeaky clean.
Either being dirty may cause sound problems.

Testocules · Dec 14, 2007

Yes. I cleaned the cart by taking it apart and cleaning the contacts on both sides of each board with a pink eraser. Cart looks legit. I cleaned both sides of the Jamma board the same way. Is there a way to clean the cart slot contacts? If so how do you do it.

I know this is going to sound dumb, but I searched for the cleaning thread already so I could learn more about what to do...and no luck. I found a thread that references the cleaning thread, but not the thread itself Unless it is not listed under clean, cleaning, cart, board, etc. Can someone point me in the right direction.

long story short, I plugged it all back in and got identical results - I had a closer listen this time and the sound effects seem garbled or jumbled up.

In the test menu it says that it is an Asian board, and the board has SNK 1999, 1999.4.30 for the manufacturing date. There is one trace that is reconnected between sides of the board and held in place with glue. But looks like pics I have seen of similar factory fixes on carts in the boot/no boot section. I am up for suggestions on what to try next.

Xian Xi · Dec 14, 2007

Are you testing with just one MVS cart?

ttooddddyy · Dec 14, 2007

Testocules said:
Is there a way to clean the cart slot contacts? If so how do you do it.

http://hardmvs.com/html/slotCleaning.htm

Testocules · Dec 14, 2007

Seems like sound effects problem only

I have tested with three carts KoF 96, Real Bout Special, and World Heroes. They all sound similar. The music seems normal, but sound effects (character voices, announcers voices, hit sound effects) are all 90% garbled. There is enough correct sound to know what they are. Also if I don't engage in fighting in KoF 96, so its almost nothing but music playing, it sounds normal until a background sound effect is used like birds or something else.

Are music and sound effects handled differently? Because it seems like there is something wrong with the sound effects but not the music.

Xian Xi · Dec 14, 2007

Testocules said:
I have tested with three carts KoF 96, Real Bout Special, and World Heroes. They all sound similar. The music seems normal, but sound effects (character voices, announcers voices, hit sound effects) are all 90% garbled. There is enough correct sound to know what they are. Also if I don't engage in fighting in KoF 96, so its almost nothing but music playing, it sounds normal until a background sound effect is used like birds or something else.

Are music and sound effects handled differently? Because it seems like there is something wrong with the sound effects but not the music.

Music and sound fx come from 2 different sources/channels/signals on the output from the cicuit iirc.

If it's an MV1C I would remove the padding on the bottom as sometimes it corrodes under there. Check it now.

Testocules · Dec 14, 2007

MV-1C pictures

Here are some pics of the board - It looks pretty nice and clean to me. No corrosion on the mobo from what I can tell. The other side looks the same.

I posted the cart slot contacts, to show their condition. I can go to Radio Shack and get some cleaner and do that part according to hardmvs.

Xian Xi · Dec 14, 2007

What is that wire thats running from a pin from the slot to a pin on the mobo? It looks like its not connected.

MKL · Dec 14, 2007

That wire is definitely sound related considering where it's soldered to on the cart slot. I guess it goes to the custom IC on the other side that encapsulates the sound generator and CPU. Check that area.

Testocules · Dec 15, 2007

I am out of town right now, when I return tomorrow, I will post some more pics of the other side. It does attach to a chip, but I do not know its purpose. I am guessing that someone will know..will update soon.

channelmaniac · Dec 15, 2007

Hey Testy,

When you get back in town give me a shout. If ya bring the board over to my house we can head out back to the workshop and plug it into my JAMMA test rig and I'll look at it.

Raymond

Xian Xi · Dec 15, 2007

That loose wire connects to pin 78 on the IC:

MKL · Dec 15, 2007

Probably it's not loose but goes to the other side through that hole above TP4, to some other pin of the NEO-YSA2 (pin 87 is my guess).

Testocules · Dec 15, 2007

Huh, did not expect to see that...

Hey guys,

First off, thanks for all your responses and help - I could not have asked for better.

Now, for some interesting photos.

These are the best I could get with the camera I had available. I am getting my wife a new camera for Christmas, but I don't suppose it would be much of a surprise if I opened it up and started using it do get pics of this board. Please let me know what your thoughts are.

-Test

channelmaniac · Dec 15, 2007

Strange looking trace on pin 84... looks either burnt or corroded.

RJ

Testocules · Dec 15, 2007

Hey RJ,

Got your pm and was about to respond. I would appreciate very much if you could have a look at it when I bring you the other neo board.

I think the corrosion is my fault. I bought the board from Run4border about 10 months ago. Shortly after I bought it, I nervously cleaned it up in the sink (rather than dishwasher) after reading your posts about what you used to do with Apple boards. As you can see the board looks fresh and minty. Just after that I went off and decided to buy a new home. The CMVS project got put on the back burner until many things on the new house were in order. Roughly nine months have passed since water touched the board, probably why the contact is corroded.

Could the corrosion be causing the sound issue?

-Test

channelmaniac · Dec 16, 2007

Possible, but ya never know until it's looked at. It doesn't look like water damage in the pic though. I've never seen water turn a trace black.

RJ

MKL · Dec 16, 2007

Pin 84 of the NEO-YSA2 corresponds to pin 47 of the sound generator YM2610 on earlier boards.

Testocules · Dec 16, 2007

The Doctor is in

RJ has kindly agreed to have a look at my ailing MV-1C this week. Once he does I will post his findings, be they good or bad.....

channelmaniac · Dec 19, 2007

Testocules said:
RJ has kindly agreed to have a look at my ailing MV-1C this week. Once he does I will post his findings, be they good or bad.....

I'll beat ya to it while you are driving home.

Fixed!

Reflowed the solder on the sound IC and cleaned the cartridge slot pins that corresponded to the sound ROM connections.

Have fun playing games on it!

Oh, and thanks for the parts board!

RJ

Testocules · Dec 19, 2007

Sound Issues fixed by channelmaniac

Its true, my Neo lives again. I took it to RJ tonight and he was able to reflow the pins on the NEO-YSA2 IC. He performed the repairs, even with that difficult 1 pin trace on the IC. I was even fortunate enough to have him find the problem and fix it while I waited.

He's very talented at what he does and a super nice guy to boot - a real professional. I give him my highest recommendation. If you need it fixed , RJ is definitely the guy to go to.

Here is a link to channelmaniac's thread for MVS repairs in case you would like to see the stuff he has done for other members.

http://www.neo-geo.com/forums/showthread.php?t=162467

Thanks RJ!

-Test

MV-1C sound issues - garbled sound effects - fixed by channelmaniac

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