Audio Issue With MVS MV4 Sound Crackle In 4 Slot

Hansuke

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May 8, 2019
Posts
27
I seem to have an audio issue with sound crackling from my MV4. It happens only on certain louder sounds/music. For example, the neo geo startup jingle sounds flawless, but for louder sounds like explosions in metal slug or the intro voice over in SamSho1, there's a crackle in the audio.

The audio is completely audible, it's not like it's garbled or anything. It sounds like the audio is coming from a really tiny phone speaker that crackles when it gets too loud. Like if you were to turn the treble up to 500% or to visualize it; over sharpening an image.

It sounds very similar to this.

I've tried listening to the audio from the mono part of the JAMMA edge and it has the same audio crackle, but for some reason, some sounds don't play, like the neo geo jingle sounds like it's missing a note or two when it plays. Game audio sounded similar to stereo, with crackle.

I've tried moving the volume slider up and down and the crackle is still present no matter when position it's in. I don't have a 4-pin adapter to test the headphone out.

I don't think it's a cartridge slot issue, as the issue is present in all 4 slots and I gave the carts and slots a cleaning.

Could this indicate a cap issue? There don't seem to be any bulging or leaking caps.
Or could this be an IC problem and would require replacing the YM2610?
 
Last edited:

maki

Edo Express Delivery Guy
Joined
Jan 1, 2022
Posts
332
the Mylar caps are most likely not the problem, which version of the MV4 do you have?

The old version with the first gen chipset and all discrete logic ICs, or the later version (second gen chipset) with their ASIC?

first version:
https://www.mvs-scans.com/index.php/MV4

later version:

IMO your problem sounds like the bus arbiter responsibly for the PCM sound died, on the first version thats a lot of discrete logic ICs, on the newer models they are ASIC and can be much harder to find, Furrtek sells custom replacements on Tindie for some of those.
 

Hansuke

n00b
Joined
May 8, 2019
Posts
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the Mylar caps are most likely not the problem, which version of the MV4 do you have?

The old version with the first gen chipset and all discrete logic ICs, or the later version (second gen chipset) with their ASIC?

first version:
https://www.mvs-scans.com/index.php/MV4

later version:

IMO your problem sounds like the bus arbiter responsibly for the PCM sound died, on the first version thats a lot of discrete logic ICs, on the newer models they are ASIC and can be much harder to find, Furrtek sells custom replacements on Tindie for some of those.
I most definitely have the older MV4. It says only "NEO-MVH MV4" on the PCB exactly where the scan shows.

Also, the board layout of my MV4 matches the MV4 on mvs-scans.

So what exactly would I need to replace? Unsure of what the bus arbiter is on the MV4
 

maki

Edo Express Delivery Guy
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Jan 1, 2022
Posts
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So what exactly would I need to replace? Unsure of what the bus arbiter is on the MV4
its tricky on your board revision, later revisions will have special ICs for that purpose, in your revision it was build using "discrete" logic ICs, lots of them, one failing will often kill the ones close to it

I'm not aware of schematics for your board, you'd need to trace out the PCM audio signals from the slot (assuming its the PCM samples that don't work in this slot) to see to which ICs they are connected.
btw. you can select & play the PCM samples from the Unibios directly, no need to start the actual game, just go into the menu when it boots

all in this can be quit tricky to solve and take a long time for a novice, if you're not up for that you could live with one slot not properly working

IMO removing the old original battery should always be done because they leak, and that will cause major problems, if you wait for that, it might be too late
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
These are my notes for slot4 on MV4 boards. This gets you info from the slot to the first logic chip.

Code:
PROG (CTRG8)
 01A <=> GND
 02A <=> GND
 03A <=> GND
 04A <=> GND
 05A <=> PIN 09 on LS245 @ R4
 06A <=> PIN 08 on LS245 @ R4
 07A <=> PIN 07 on LS245 @ R4
 08A <=> PIN 06 on LS245 @ R4
 09A <=> PIN 05 on LS245 @ R4
 10A <=> PIN 04 on LS245 @ R4
 11A <=> PIN 03 on LS245 @ R4
 12A <=> PIN 02 on LS245 @ R4
 13A <=> PIN 09 on LS245 @ R3
 14A <=> PIN 08 on LS245 @ R3
 15A <=> PIN 07 on LS245 @ R3
 16A <=> PIN 06 on LS245 @ R3
 17A <=> PIN 05 on LS245 @ R3
 18A <=> PIN 04 on LS245 @ R3
 19A <=> PIN 03 on LS245 @ R3
 20A <=> PIN 02 on LS245 @ R3
 21A <=> PIN 01 on LS245 @ R4 and PIN 01 on LS245 @ R3 and PIN 01 on LS245 @ R4 and PIN 09 on F244 @ R2
 22A <=> PIN 07 on  F244 @ R2
 23A <=> PIN 05 on  F244 @ R2
 24A <=> PIN 03 on  F244 @ R2
 25A <=> PIN 12 on  F244 @ R2
 26A <=> PIN 14 on  F244 @ R2
 27A <=> PIN 16 on  F244 @ R2
 28A <=> PIN 18 on  F244 @ R2
 29A <=> VCC
 30A <=> VCC
 31A <=> VCC
 32A <=> VCC
 33A <=> PIN 18 on LS244 @ R6
 34A <=> NC
 35A <=> NC
 36A <=> NC
 37A <=> NC
 38A <=> NC
 39A <=> NC
 40A <=> NC
 41A <=> NC
 42A <=> PIN 19 on LS245 @ S3/S4/S5/S6/P5 (also connects to 42A on CHA slot4)
 43A <=> PIN 16 on LS244 @ R6
 44A <=> PIN 14 on LS244 @ R6
 45A <=> PIN 12 on LS244 @ R6
 46A <=> PIN 07 on LS244 @ R6
 47A <=> PIN 05 on LS244 @ R6
 48A <=> PIN 03 on LS244 @ R6
 49A <=> PIN 18 on LS244 @ R5
 50A <=> PIN 16 on LS244 @ R5
 51A <=> PIN 14 on LS244 @ R5
 52A <=> PIN 12 on LS244 @ R5
 53A <=> PIN 09 on LS244 @ R5
 54A <=> PIN 07 on LS244 @ R5
 55A <=> PIN 05 on LS244 @ R5
 56A <=> PIN 03 on LS244 @ R5
 57A <=> GND
 58A <=> GND
 59A <=> GND
 60A <=> GND

 01B <=> GND
 02B <=> GND
 03B <=> GND
 04B <=> GND
 05B <=> PIN 09 on LS244 @ S4
 06B <=> PIN 07 on LS244 @ S4
 07B <=> PIN 05 on LS244 @ S4
 08B <=> PIN 03 on LS244 @ S4
 09B <=> PIN 18 on LS244 @ S4
 10B <=> PIN 16 on LS244 @ S4
 11B <=> PIN 14 on LS244 @ S4
 12B <=> PIN 12 on LS244 @ S4
 13B <=> PIN 09 on LS244 @ S3
 14B <=> PIN 07 on LS244 @ S3
 15B <=> PIN 05 on LS244 @ S3
 16B <=> PIN 03 on LS244 @ S3
 17B <=> PIN 18 on LS244 @ S3
 18B <=> PIN 16 on LS244 @ S3
 19B <=> PIN 14 on LS244 @ S3
 20B <=> PIN 12 on LS244 @ S3
 21B <=> PIN 18 on  F244 @ S2
 22B <=> PIN 16 on  F244 @ S2
 23B <=> PIN 14 on  F244 @ S2
 24B <=> PIN 12 on  F244 @ S2
 25B <=> PIN 03 on  F153 @ R7
 26B <=> PIN 13 on  F153 @ R7
 27B <=> PIN 03 on  F153 @ S7
 28B <=> PIN 13 on  F153 @ S7
 29B <=> VCC
 30B <=> VCC
 31B <=> VCC
 32B <=> VCC
 33B <=> PIN 09 on  F244 @ S2
 34B <=> PIN 07 on  F244 @ S2
 35B <=> PIN 18B on CHA SLOT4
 36B <=> NC
 37B <=> NC
 38B <=> NC
 39B <=> NC
 40B <=> NC
 41B <=> PIN 18 on LS245 @ S6
 42B <=> PIN 17 on LS245 @ S6
 43B <=> PIN 16 on LS245 @ S6
 44B <=> PIN 15 on LS245 @ S6
 45B <=> PIN 14 on LS245 @ S6
 46B <=> PIN 13 on LS245 @ S6
 47B <=> PIN 12 on LS245 @ S6
 48B <=> PIN 11 on LS245 @ S6
 49B <=> PIN 18 on LS245 @ S5
 50B <=> PIN 17 on LS245 @ S5
 51B <=> PIN 16 on LS245 @ S5
 52B <=> PIN 15 on LS245 @ S5
 53B <=> PIN 14 on LS245 @ S5
 54B <=> PIN 13 on LS245 @ S5
 55B <=> PIN 12 on LS245 @ S5
 56B <=> PIN 11 on LS245 @ S5
 57B <=> GND
 58B <=> GND
 59B <=> GND
 60B <=> GND

CHA (CTRG7)
 01A <=> GND
 02A <=> GND
 03A <=> PIN 12 on LS244 @ N4
 04A <=> PIN 14 on LS244 @ N4
 05A <=> PIN 16 on LS244 @ N4
 06A <=> PIN 18 on LS244 @ N4
 07A <=> PIN 09 on LS244 @ N4
 08A <=> PIN 07 on LS244 @ N4
 09A <=> PIN 05 on LS244 @ N4
 10A <=> PIN 03 on LS244 @ N4
 11A <=> PIN 12 on LS244 @ N3
 12A <=> PIN 14 on LS244 @ N3
 13A <=> PIN 16 on LS244 @ N3
 14A <=> PIN 18 on LS244 @ N3
 15A <=> PIN 09 on LS244 @ N3
 16A <=> PIN 07 on LS244 @ N3
 17A <=> PIN 05 on LS244 @ N3
 18A <=> PIN 03 on LS244 @ N3
 19A <=> PIN 03 on  F253 @ B1
 20A <=> PIN 03 on  F253 @ C1
 21A <=> PIN 03 on  F253 @ D1
 22A <=> PIN 03 on  F253 @ E1
 23A <=> PIN 03 on  F253 @ F1
 24A <=> PIN 03 on  F253 @ G1
 25A <=> PIN 03 on  F253 @ N1
 26A <=> PIN 03 on  F253 @ P1
 27A <=> PIN 03 on  F253 @ R1
 28A <=> PIN 03 on  F253 @ S1
 29A <=> VCC
 30A <=> VCC
 31A <=> VCC
 32A <=> VCC
 33A <=> PIN 03 on  F253 @ A7
 34A <=> PIN 03 on  F253 @ B7
 35A <=> PIN 03 on  F253 @ C7
 36A <=> PIN 03 on  F253 @ H7
 37A <=> PIN 03 on  F253 @ J7
 38A <=> PIN 03 on  F253 @ K7
 39A <=> NC
 40A <=> NC
 41A <=> NC
 42A <=> PIN 19 on LS245 @ R3/R4/S5/S6/P5 (also connects to 42A on PROG slot4)
 43A <=> PIN 12 on LS244 @ N6
 44A <=> PIN 14 on LS244 @ N6
 45A <=> PIN 16 on LS244 @ N6
 46A <=> PIN 18 on LS244 @ N6
 47A <=> PIN 09 on LS244 @ N6
 48A <=> PIN 07 on LS244 @ N6
 49A <=> PIN 05 on LS244 @ N6
 50A <=> PIN 03 on LS244 @ N6
 51A <=> PIN 12 on LS244 @ N5
 52A <=> PIN 14 on LS244 @ N5
 53A <=> PIN 16 on LS244 @ N5
 54A <=> PIN 18 on LS244 @ N5
 55A <=> PIN 09 on LS244 @ N5
 56A <=> PIN 07 on LS244 @ N5
 57A <=> PIN 05 on LS244 @ N5
 58A <=> PIN 03 on LS244 @ N5
 59A <=> GND
 60A <=> GND
 
 01B <=> GND
 02B <=> GND
 03B <=> PIN 12 on LS244 @ P4
 04B <=> PIN 14 on LS244 @ P4
 05B <=> PIN 16 on LS244 @ P4
 06B <=> PIN 18 on LS244 @ P4
 07B <=> PIN 03 on LS244 @ P4
 08B <=> PIN 05 on LS244 @ P4
 09B <=> PIN 07 on LS244 @ P4
 10B <=> PIN 09 on LS244 @ P4
 11B <=> PIN 12 on LS244 @ P2
 12B <=> PIN 14 on LS244 @ P2
 13B <=> PIN 16 on LS244 @ P2
 14B <=> PIN 18 on LS244 @ P2
 15B <=> PIN 03 on LS244 @ P2
 16B <=> PIN 05 on LS244 @ P2
 17B <=> PIN 07 on LS244 @ P2
 18B <=> PIN 09 on LS244 @ P2
 19B <=> PIN 13 on  F253 @ B1
 20B <=> PIN 13 on  F253 @ C1
 21B <=> PIN 13 on  F253 @ D1
 22B <=> PIN 13 on  F253 @ E1
 23B <=> PIN 13 on  F253 @ F1
 24B <=> PIN 13 on  F253 @ G1
 25B <=> PIN 13 on  F253 @ N1
 26B <=> PIN 13 on  F253 @ P1
 27B <=> PIN 13 on  F253 @ R1
 28B <=> PIN 13 on  F253 @ S1
 29B <=> VCC
 30B <=> VCC
 31B <=> VCC
 32B <=> VCC
 33B <=> PIN 13 on  F253 @ A7
 34B <=> PIN 13 on  F253 @ B7
 35B <=> PIN 13 on  F253 @ C7
 36B <=> PIN 13 on  F253 @ H7
 37B <=> PIN 13 on  F253 @ J7
 38B <=> PIN 13 on  F253 @ K7
 39B <=> PIN 03 on  F253 @ L7
 40B <=> PIN 13 on  F253 @ L7
 41B <=> PIN 03 on  F253 @ M7
 42B <=> PIN 13 on  F253 @ M7
 43B <=> PIN 03 on  F253 @ N7
 44B <=> PIN 13 on  F253 @ N7
 45B <=> PIN 03 on  F253 @ P7
 46B <=> PIN 13 on  F253 @ P7
 47B <=> PIN 12 on  F244 @ P6
 48B <=> PIN 14 on  F244 @ P6
 49B <=> PIN 16 on  F244 @ P6
 50B <=> PIN 18 on  F244 @ P6
 51B <=> PIN 11 on LS245 @ P5
 52B <=> PIN 12 on LS245 @ P5
 53B <=> PIN 13 on LS245 @ P5
 54B <=> PIN 14 on LS245 @ P5
 55B <=> PIN 15 on LS245 @ P5
 56B <=> PIN 16 on LS245 @ P5
 57B <=> PIN 17 on LS245 @ P5
 58B <=> PIN 18 on LS245 @ P5
 59B <=> GND
 60B <=> GND
 

Hansuke

n00b
Joined
May 8, 2019
Posts
27
its tricky on your board revision, later revisions will have special ICs for that purpose, in your revision it was build using "discrete" logic ICs, lots of them, one failing will often kill the ones close to it

I'm not aware of schematics for your board, you'd need to trace out the PCM audio signals from the slot (assuming its the PCM samples that don't work in this slot) to see to which ICs they are connected.
btw. you can select & play the PCM samples from the Unibios directly, no need to start the actual game, just go into the menu when it boots

all in this can be quit tricky to solve and take a long time for a novice, if you're not up for that you could live with one slot not properly working

IMO removing the old original battery should always be done because they leak, and that will cause major problems, if you wait for that, it might be too late
Yea, at the moment, I definitely don't have to toolset or knowledge to solve this issue through tracing ICs. Still hoping recapping the audio section will clear it up.

It would be nice if it was only one slot that had this audio crackle problem, but like I said in the first post, it's there in all 4 slots.

Are batteries still prone to leaking if it's still working? It still holds charge to keep the calendar and settings saved.

Thanks @ack for posting those notes! Hopefully I'll get around to be able to use it.
 

ack

Ninja Combat Warrior
15 Year Member
Joined
Apr 9, 2009
Posts
538
I would definitely do the cap replacement first. I misread your title/first post thinking the issue was only on slot 4.
 

Hansuke

n00b
Joined
May 8, 2019
Posts
27
I would definitely do the cap replacement first. I misread your title/first post thinking the issue was only on slot 4.
After reading back the title of the thread, yea, it is kind of confusing. I wish we could edit thread titles...
 

BIG BEAR

SHOCKbox Developer,
20 Year Member
Joined
Dec 14, 2001
Posts
8,230
How high do you have the audio up with the slider? If it's up to maximum,turn it down to the middle point and see what happens.
BB
 

Hansuke

n00b
Joined
May 8, 2019
Posts
27
How high do you have the audio up with the slider? If it's up to maximum,turn it down to the middle point and see what happens.
BB
I've tried it at 25%, 50%, and 75%. The crackle is present at all volumes it seems, it sounds less loud as the volume decreases of course.

I've also now noticed that the audio in the right channel sounds louder than the left channel.

I really hope that this is just a cap issue and recapping fixes everything.
 

Hansuke

n00b
Joined
May 8, 2019
Posts
27
Update Post:

So I've recapped all the electrolytic caps in the MV4. It fixed the audio levels being unbalanced and the audio sounds louder at a lower setting on the volume slider.
However, the audio crackle remains...

I went ahead and replaced both the YM2610 and the YM3016 DAC.
No difference.

I'm kind of stumped now on what to do...

Also, I managed to get a headphone jack adapter for the 4 pin headphone out. Tested out the audio there, and for some reason only the left channel is working. In the Sound Test menu of the Hardware Test, both left, right, and center plays through the left channel through the headphone out.

Looked at the wiring of the adapter cable and it seems to check out. Stereo from the connector edge sounds fine and plays correctly through the correct channels.

The audio I've heard from the headphone out still has that same crackle as the audio from the edge connector.

Any suggestions on how to proceed to fix the crackle would be welcome.
 

maki

Edo Express Delivery Guy
Joined
Jan 1, 2022
Posts
332
Can you post a video that with the audio crackle?

You can upload it to imgur, it will compress, just don't make it too long.
 

Hansuke

n00b
Joined
May 8, 2019
Posts
27
Can you post a video that with the audio crackle?

You can upload it to imgur, it will compress, just don't make it too long.
There's a link in the opening post to an audio recording that has the same issue as me. You can hear the crackle in the highs of the sample playback during the Blazing Star opening theme. I also get distorted lower bass like the drums in Nakoruru's stage in Samurai Shodown 1 or Kage's stage. It sounds like a broken sound woofer.

I figure my next step would be to probe the DAC and output the audio from there to see if it sounds good coming out of the DAC, if so, that means the problem is in the analog amplification section of the audio circuit...
 

BIG BEAR

SHOCKbox Developer,
20 Year Member
Joined
Dec 14, 2001
Posts
8,230
Did you try using different speakers?
Did you check to make sure there were no broken traces /tracks at the 2610?
BB
 

Neo Alec

Ned's Ninja Academy Dropout
20 Year Member
Joined
Dec 7, 2000
Posts
11,923
I've tried listening to the audio from the mono part of the JAMMA edge and it has the same audio crackle, but for some reason, some sounds don't play, like the neo geo jingle sounds like it's missing a note or two when it plays. Game audio sounded similar to stereo, with crackle.
The MV4 outputs stereo on the jamma edge. You're not hearing some sounds from the Neo Geo jingle because you're only hearing one of the two stereo channels.
 

channelmaniac

Mr Neo Fix-it
15 Year Member
Joined
Nov 29, 2005
Posts
4,275
I saw your post over on another forum about this and asked over there for a video. The Neo Geo has 2 different sounds - the ones generated by the YM2610 and the ones played back from samples in ROMs. Your "static" could simply be a bad trace on the top board that is keeping all the sample data from being played back properly. This is why I asked for a video over there.
 
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