Wierd sound issues Neo Geo MVS 4 Slot. Wiring or board? FIXED!!!!

Hi,

I just came into my first NeoGeo cabinet- a MVS 4-slot. I have noticed that full sound comes out of the right channel, but some sound comes out of the left (this happens with both speaker and headphone connector output). The sound coming out of the left channel appears to be more higher-pitched sound. For example in Metal Gear the first time I hear sound from the left channel is when I pick up special items (when it dings). I also hear the chuga chuga of the helicopter when it comes in. It's not an intermittent sound issue as it does the same thing all the time. I never get full sound in the left speaker. It's just some of the sound effects. The problem follows the system, not the cart.

I am looking for some pointers here. The board is well used and was in an arcade for quite some time and had a ton of crap on the board (dust and sticky stuff). I greatly cleaned the board with a paintbrush to get all of the dust off. Not sure what to do about the sticky stuff. I have suspicions that it's probably some kind of beverage that was spilled on the cab. I also think that's where some of my problem lies. Unfortunately I don't have another test board to plug in and test. The wiring looks fairly clean (not a lot of splices, no breaks).

I have read a few posts on the board, but none quite like this.

Thanks in advance.

Don

Mine is just like that.. I swaped the wires around to see if it was the speaker but its not cause when i swap the cables around its the same but the left is louder then the right. Though i believe the headphones are fine.

The other thing mine does is that it seems to take away for it to warm up as it does not get to full volume at first.. Gets louder after time.

The only thing i can tell from the wiring that looks normal is that the ground wire is shared.

Thanks

Thanks for the reply.

Are you just living with it, or have you taken steps to fix it?

I will try to swap the speaker cables tonight. I have the MVS-4-25 (ver. 3) http://www.hardmvs.com/xml/usa/usCabs.htm.

I would like to fix the issue if I can, but I think it will have to replace the board or the chip. Anyone had any experience with replacing the YM2610 chip or having their board repaired? I know the chip is surface mounted and probably a pain in the neck to replace.

Don

heh i've got the same cab..Well i've only had the cab for a few weeks and i'm workin on other things right now that are more important like replacing the whole top guts.

So basicly living with it atm.. Not really that noticeable unless your thinking about it.

Oh yeah.. btw i've unsoldered a chip like that before with my old AES system when i had to unsolder the bios chip and install a socketed chip holder.. Not a prob here.. went smooth.. so if worse comes to worse its not that hard to do if it comes down to the sound chip.. I'm hoping the prob lies in the harness wiring.

Checked the Speakers

I reversed the speaker connectors (left to right, right to left) and it follows it just like yours does.

I also tried cleaning the connector (Jamma Finger type) on both the connector harness (PITA) and the board. It didn't seem to make a difference, but I am not sure if that's actually the right connector. Based on the pinouts I have seen on HardMVS it looks like that's where the audio comes out.

Are you redoing the lights like in

http://www.neo-geo.com/forums/showthread.php?t=99020

GL with that. I need to do that too. I just need some money

Don

Yup.. Whenever i get the money.. hopefully the guy still does it by the time i get to him.

I had to replace everything in the top since the former owner gutted it for a single game. Just put a large marquee at the top where the 4 is. And added a lame florescent light.

I already have the light panels here and the marquee clear holder. Waitin on a package if i ever get it from a guy on ebay with the marquee cover and the wood frame behind it. heh cant wait to put it all back to normal as the top looks like crap now.

Other then the sound issue, everything else on the cab works perfect.

you are sure that it is wired properly for stereo right?

Hi Norton,

Can you point me in the right direction on how to check. I see that there are 3 wires coming up from the wiring harness to the speakers. There is a shared ground and two positive wires.

I know that these are 2 discrete channels because when I play a game, some of the sound effects will come out of the left speaker independent from the right. For example on Metal Slug 1, when I pick up special items and you hear that little ding noise, that sound is only out of the left channel. All other sound is out of the right channel. Another example of this would be when you select the choice of the characters in Samurai Showdown IV, that dinging noise comes out only on the left side.

This happens on both the speakers and the headphone jacks. It's the same.

Don

Yeah i forgot that i checked out the sound with the hardware test mode long ago.. The right and left channels work properly so it must be wired up right from the harness.. Though i still have not checked the wires to see if theres any repairs to them.

I made some very old threads in tech about a similar problem...So long ago,I don't think they could be searched out.

My MVS 25 Candy Cab use to do the same thing you speak of...I thought it was the 4 slot mobo so I took it out and put it in my Big Red MVS 25 Cab and it was fine.
I took out the 4 slot in the Big Red, put it in the Candy cab and it did the same thing you speak of..So that tells me it's not the board it's the wiring in the cab..

What I did is kept chcking on the ground wiring since the cabs wiring had been messed with9though neat) for CPSII before I got it..
I don't remeber what I did but moving one of the grond wires around seemed to solve the problem..

hmm.. Well then i guess we should start going threw the wiring for a faulty ground. Could just be some wire crossing over the left speaker wire thats causing some interfearance since these wires are not shielded.

LMK how it goes..Hope it works out..

Let me say...It drove me nuts!!!!


I even changed the power supply and it wasn't the problem..I wound up putting the old ps back in the cab..

My cab's problem is simular. Difference is that I get no sound from the left channel. The right channel starts off with a low volume, and gradually gets louder. I expect with mine that is needs the caps replaced on the sound curcuit. I've just not had time to change them out. I think one of the caps for the left channel is just gone, and that's why I don't have any sound on that side.

Thanks, what are these green wires for?

Thanks to everyone.

I ran the sound test and I get sound from the left channel and center options, but no sound from the right channel.

I noticed today that the power cord has a missing ground wire. I will start by getting a new power cord and replace that first.

I also found two green (normally ground) wires that have round eyelets attached to them. I am unsure as to where they are supposed to be connected at this point. These wires come out of the sleeving on the board side of the 2 60 pin connector cables next to the Jamma-style connector. These are the connectors for the card reader and headphone jacks. I don't think it is entirely related to the sound problems I am experiencing, but I want to conver all the bases here. Are these ground wires attached to the board in some way- maybe attached to the shielding? Unfortunately, I don't see them listed in the schematic in the manual. It just breaks out the 2 60 pin connections and the 4 pin connection.

donholio said:

Thanks to everyone.

I ran the sound test and I get sound from the left channel and center options, but no sound from the right channel.

I noticed today that the power cord has a missing ground wire. I will start by getting a new power cord and replace that first.

I also found two green (normally ground) wires that have round eyelets attached to them. I am unsure as to where they are supposed to be connected at this point. These wires come out of the sleeving on the board side of the 2 60 pin connector cables next to the Jamma-style connector. These are the connectors for the card reader and headphone jacks. I don't think it is entirely related to the sound problems I am experiencing, but I want to conver all the bases here. Are these ground wires attached to the board in some way- maybe attached to the shielding? Unfortunately, I don't see them listed in the schematic in the manual. It just breaks out the 2 60 pin connections and the 4 pin connection.

Click to expand...

I had those same ground wires just dangling also. I just attached to the shield on the main board. Made no difference though.

Yeah those 2 ground wires are attached from the corner screw of the metal top of the 4 slot board and the other end to 1 of the 4 mounting bolts on the left controller. Looks pointless but i guess it wont hurt.

Progress so far

OK,

I wanted to update on where I am. I have replaced the power cord with one that has the ground intact. Then I wired up the 2 ground wires to the housing on the board.

No difference so far. I am going to investigate the MVS connector and make sure the wires are going to the correct locations. I have already checked the wiring up to the speakers in the top of the cabinet and I have a ground wire with Left and Right going up there. The more and more I look at this, the more and more I think it's the sound chip on the board. I know there has been some beverage spilled on the cabinet at some point, and I know liquid has gotten down to the general area of the shelf the board sits on. I have no specific knowledge the board was wet, but based upon these issues...

If there is anyone local to me (SF bay area) who would be williing to bring over their board, or let me bring over my board for a quick test. Please PM me. I just want to know where the problem is so I can fix it.

Thanks in advance

-Don

FIXED!!!

Well, the problem was that 2 of the pins of an AD converter chip were soldered together (WTF). I found it when I was replacing all of the caps around the amp. I replaced the caps, unsoldered the pins and BINGO Stereo sound!!!

Anyone need a HA13001? I have one coming to me and I don't need it anymore.

-Don

donholio said:

Well, the problem was that 2 of the pins of an AD converter chip were soldered together (WTF). I found it when I was replacing all of the caps around the amp. I replaced the caps, unsoldered the pins and BINGO Stereo sound!!!

Anyone need a HA13001? I have one coming to me and I don't need it anymore.

-Don

Click to expand...

Wow!!,well that's good news..

Do you happen to have a picture of the area=2 of the pins of an AD converter chip were soldered together ..

donholio said:

Well, the problem was that 2 of the pins of an AD converter chip were soldered together (WTF). I found it when I was replacing all of the caps around the amp. I replaced the caps, unsoldered the pins and BINGO Stereo sound!!!

Anyone need a HA13001? I have one coming to me and I don't need it anymore.

-Don

Click to expand...

Did you happen to try the sound prior to desoldering those 2 pins? It would be interesting to know if that was the problem, or if replacing the CAPS fixed the issue. Glad you got it working.

WOW.. Yeah a pic of that AD chip would be helpfull as i'm gona have a full day to check that out tomorrow if i get the info in time.

I replaced about 1/2 the caps then I tested the machine. No luck. I figured I would replace the rest since I had already bought the caps and as I was replacing the 3 22mf caps in a row on the board I saw the blob of solder on the pins of the chip. It's one of the smaller chips (it looked like it had 8 pins I think). You can see one in the pics in this thread: http://www.neo-geo.com/forums/showpost.php?p=1905056&postcount=10. My board is different than this one, but it's the chip surrounded by 3 caps on the bottom and 1 on the right about middle top of the bottom pic. I don't remember which 2 pins were bridged, but it was 2 of the outside pins not the inside pins (1 and 2, or 3 and 4, or 5 and 6, or 7 and 8).

Once I removed the excess solder and re-soldered the chip, I tested it and everything worked great. Between not working and working, I just replaced the 3 caps. It could be that, but based upon what I have read about recapping (usually issues with sound going loud to soft or soft to loud, or motorboating) I have a feeling this was it. I could be completely off base. Remember the issue I was having was that sound was perfect on the right speaker, but left only played the "special" sounds like when you select a character in SamSho. I had a hum coming from the speaker that I am not sure I mentioned. I originally thought it was the el lights up in the marquee, but I removed them and the sound remained.

I also found 2 reversed resistors on the board (100 ohm and 470 ohm) I fixed. That's why I tested things halfway through the replacement process. It looks like whomever worked on this board had even less knowledge than I got from my electronics class 15 years ago. It's amazing what you remember.

Sorry I don't have a camera right now to take a pic, but hopefully my directions can point you in the right direction. If you really want to know, I will update the thread when I can borrow a camera. I should be able to borrow one later weekend or next week.

Thanks again guys!

-Don

Here's another good pic of the chip:
http://www.neo-geo.com/forums/showpost.php?p=1770187&postcount=9
They talk about it being a BA4558 or BA10324. My board's a 4 slot and this one's a 1 slot.

In the thread they talk about it being an opamp. Don't know why I called it an A/D converter in the prior posts.
http://www.neo-geo.com/forums/showthread.php?t=134661

-Don

donholio said:

I also found 2 reversed resistors on the board (100 ohm and 470 ohm) I fixed. That's why I tested things halfway through the replacement process. It looks like whomever worked on this board had even less knowledge than I got from my electronics class 15 years ago. It's amazing what you remember.
Thanks again guys!

-Don

Click to expand...

Resistors can go either way, it makes no difference.