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Thread: Echo / repeating sounds with Metal Slug 4?

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    Echo / repeating sounds with Metal Slug 4?

    Hey folks,

    I recently got an MS4 cart that was sold as working 100%. I am having an unusual sound issue: the sample sounds will often repeat, e.g. "Thank You!" repeated several times when rescuing a prisoner. Also, it seems like the music track will sometimes change abruptly. Finally, the audio will usually cut out completely after a few minutes not in the same place every time. I have two other MS carts that run fine.

    I suspect dirty contacts or slot, but alcohol + q-tips on the cart don't seem to change it. The next step is to spray some contact cleaner into the slot as I have seen graphics issues with other carts that seemed to go away after cleaning the cart contacts, but maybe that is not enough here. Still need to buy the spray, though.

    Does this seem like a dirty contacts / slot issue, or something else?

    Note that this is with an MV-1 (original BIOS), which I know has compatibility issues with multicarts, but AFAIK should be OK with legit carts.

    Vaguely similar to this (e.g. sound cutting out), may be related: http://www.neo-geo.com/forums/showth...-sound-problem

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    I did some more contact cleaning, and applied the contact spray to the slot as well. No change in the sound issue. See the link below for a sample:

    https://www.dropbox.com/s/6sn24lfkynre9y8/ms4.mov?dl=0

    It seems to play "Rocket Launcher" at the same time as the "Go" sound. Unfortunately I don't have another MVS board to test with.

    Any thoughts?

  3. #3
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    Another strange one. I can't see how sound effects could be mixed together, except if both are triggered to play at the same time.
    If the sound program had an issue, since it's "encrypted" I think there wouldn't be sound at all.
    If the sound data had an issue, the sounds and music would be screeching.

    I'd place my bet on the slot. Trying to guess what's happening, I can't see much of a relation between the "Go" and the "Rocket laucher" sound codes.
    Not sure why your other carts work, maybe they're not using some of the bits for their sound codes.

    Do you have a multimeter to check continuity ?

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    Thanks for the reply. After listening / playing several times, it seems like the music track also restarts when this happens. It can happen with really any sound effect: insert coin, "Heavy Machine Gun", "Rocket Launcher", "Thank You", etc. and it is fairly random. Maybe the sound program is restarting from some point? (or the Z80 resetting?)

    I agree that this really feels like a contact / slot issue. I had seen graphics glitches and sound screeching with this cart, but cleaning has fixed those. At this point I have used q-tips, alcohol, toothbrush, WD-40 contact cleaner (the specialist one), and a pink eraser. I have not bought / tried Deoxit. Would that be worth trying?

    The alternative is some compatibility issue between this newer cart (MS4) and older board (MV1). I have tested with MS1, MS2, and MSX carts and they work fine, though they are older games.

    ... or bad ROMs, but as you say it seems like the problem would be more serious if that were the case.

    I do have a multimeter to check connectivity. Any particular traces I should look at? Thanks!
    Last edited by Mauricio; 03-10-2018 at 04:32 PM.

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    I didn't repair many carts, but I never had to use more than alcohol, erasers and microfiber cloth to wipe off residue. Some contacts were black (not even dark grey) and that was enough to see the gold plating again. In my opinion your cart's contacts are clean.

    (No offense and maybe stupid question: it's an original one, right ?)

    MS4 does use a more "recent" chip for audio but if something was wrong with it you'd get chopped samples or screeches.
    I can imagine the Z80 having more chances of freezing than resetting, also if music and sound effects continue to play then it's still running fine.

    The only difference MS4 has with the previous titles is the use of the "encryption" chip which deals with graphics and the sound program. If anything goes wrong with it, sprites graphics go nuts and the Z80 crashes. That's visibly not the case so I guess the decryption is working correctly.

    Also in MAME I'm seeing that MS4 uses mostly 2-byte commands for audio, MS1/2/X seems to use mostly 1-byte values.

    You can try checking pins 41, 50, 51 and 52 on the PRO-B0 chip (https://wiki.neogeodev.org/index.php?title=PRO-B0).
    PRO-B0 41 -> Z80 21
    PRO-B0 50 -> Z80 22
    PRO-B0 51 -> Maybe PRO-C0, not sure which pin
    PRO-B0 52 -> PRO-C0 17
    I'd be suspicious of pin 52 (SDW).

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    You verify that it's not teh boot?

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    I have a shock troopers 2 cart that does that. Itís original Roms but has lots of solder spots that look like it was done by hand and not a wave machine. I think they could have been transplants from an AES cart. Did you look at the boards to see if anything look peculiar?

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    Thanks for the replies! The cart is almost certainly original, but I have attached photos here just in case. I don't see anything suspicious and the solder points look good, but you might see something I don't. Most of the board surface feels tacky though... is that expected? I did ask the seller, and he confirmed it was working fine before it shipped.

    furrtek: I checked continuity on those pins, and everything seems fine. However, the pin IDs seem different than what you suggested: pins 42 (not 41) and 49 (not 50) go to the Z80, though the Z80 is a 40-pin DIP in my case. The other pins go to the NEO-D0. In any case, none of those traces appear to be broken.
    Attached Images Attached Images

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    Blame madman
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    Yeah, you're good on that, it's legit.

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    Not seeing anything special either.
    Are JV5 and JV6 (under the V1 ROM) soldered correctly ? JV6 is quite off its pads.

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    Quote Originally Posted by furrtek View Post
    Not seeing anything special either.
    Are JV5 and JV6 (under the V1 ROM) soldered correctly ? JV6 is quite off its pads.
    Did you ever make sure that people that ordered you converter got taken care of?
    Quote Originally Posted by Skillzguy View Post
    I sometimes wish I didn't have Aspergers as I feel game related collecting would be a mild hobby rather than an obsession.

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    Since a while now, yes. Still making some from time to time based on a waiting list, works better for everyone.
    DM or other thread if we need to talk about that ?

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    Quote Originally Posted by furrtek View Post
    Are JV5 and JV6 (under the V1 ROM) soldered correctly ? JV6 is quite off its pads.
    I noticed that too, but it doesn't seem broken. To be sure, I just checked continuity and it is good.

    One odd (but perhaps correct) thing is that one of the traces from the JVs apparently goes toward the NEO-PCM2 IC but stops short... look right under the "2" in the printed "NEO-PCM2." According to the schematic, that pin isn't supposed to be connected to anything, but it is strange that a trace is run to that spot.

    At this point I am tempted to get another MS4 or even another NG board (like an MV-1A) to compare, but this has already turned into quite the time sink.

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    I have a Ms4 cart with the exact same problem must be some bad components on those boards , what region is your cart?

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    Quote Originally Posted by xardion View Post
    I have a Ms4 cart with the exact same problem must be some bad components on those boards , what region is your cart?
    Good to know that I am not alone! I thought the carts were universal, i.e. no region? The MV1 board has an (original) US BIOS.

    Now that I think of it... do you think getting a Uni BIOS would make a difference?

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    The trace stopping right before the chip is part of the ground plane, it's just there to fill in the gap with copper, no real use.
    I don't think getting an Unibios would change anything. You could use the Jukebox function to test music though.

    Don't have many more ideas :/

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    Quote Originally Posted by furrtek View Post
    Don't have many more ideas :/
    No worries! Thanks for putting some thought into it. The seller has offered to exchange it, but now I am wondering if even that will do it based on xardion's comment.

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    Another thought: voltage? I am getting 4.92V at the NEO-PCM2 chip on the cartridge. Could being a bit under 5.0V lead to such glitches? Again, other carts are fine.

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    That's fine, below 4.75V would be alarming.

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    Another update... I got a Universe BIOS to see if that would help me diagnose this. The CRC checks are all OK, and the Jukebox plays about 10 different tracks. Should the Jukebox be able to play more than that? The music in the Jukebox doesn't have the sound issue, though I guess that is not surprising. I tried all three regions as well as arcade and AES modes... all of them still have the sound problem.

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    My MS4 cart had issues with the music and sounds randomly stopping playing, however they were not duped. Burned and replaced teh M1 chip, cart works perfectly now. Worth a try, I guess, unless you prefer to keep your cart pristine but in non-working condition.

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    Quote Originally Posted by aha2940 View Post
    My MS4 cart had issues with the music and sounds randomly stopping playing, however they were not duped. Burned and replaced teh M1 chip, cart works perfectly now. Worth a try, I guess, unless you prefer to keep your cart pristine but in non-working condition.
    Good to know! That at least sounds somewhat similar, in that this one will also have sound cutting in and out. I am in the process of exchanging it with the seller, and will let you know if the replacement has the same problem.

    Thinking aloud: The ROM CRC check passed with the Universe BIOS, but I think it only checks the program ROMs, not the M1 / sound ROM, so that won't help me find a problem there.

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    Quote Originally Posted by Mauricio View Post
    The ROM CRC check passed with the Universe BIOS, but I think it only checks the program ROMs, not the M1 / sound ROM, so that won't help me find a problem there.
    That is correct.

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    I got the replacement cartridge from the very patient seller... and still the same problem! At this point it really has to be a problem or incompatibility with my MV-1. I am going to look into getting a cheap alternate one-slot board, maybe a MV-1B or MV-1C. Any quick recommendations for which one, or where to buy? (I will also search / ask around.)

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    Quote Originally Posted by Mauricio View Post
    I got the replacement cartridge from the very patient seller... and still the same problem! At this point it really has to be a problem or incompatibility with my MV-1. I am going to look into getting a cheap alternate one-slot board, maybe a MV-1B or MV-1C. Any quick recommendations for which one, or where to buy? (I will also search / ask around.)
    You can get them on ebay. The MV-1C and MV-1B are both nice and reliable. The design is different, the 1C the cart is inserted vertical, in the 1B is inserted horizontal. Preferences, I guess.

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