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Thread: MV1C w/ Unibios 3.0 - Illegal Instruction

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    MV1C w/ Unibios 3.0 - Illegal Instruction

    Hey folks,

    I've been slowly gathering pieces to build a Jamma / Neo Geo cabinet and finally got enough together to test my MV1C board. I bought it used recently, it was pre-modded with Unibios 3. The seller said he got it long ago, was going to consolize it but never got around to it.

    Anyhow, I did some testing and got it working fine on a test work area, so then moved it into its cabinet that has a proper CRT last night. I did some basic video tests as the CRT was new to me as well, it seemed to work fine last night.

    This morning I wired up the controls, powered it up, and just get an Illegal instruction error from Unibios:

    I undid my controller wiring in case something was grounded strangely or something, it did not fix it. I also have another JAMMA board which I inserted and seems to work fine.

    Gallery with a few photos of the error, as well as an MVS cart running fine on it last night:

    https://imgur.com/a/smEfn

    Note that initial testing I did get a scrambled screen (last image in gallery). I had to clean the JAMMA edge several times and then it worked. I tried that again here but am not having any luck.

    You can also see that the wiring for the BIOS looks a bit messy, I most certainly have not attempted to dig under the hot glue in to any of that.

    Any thoughts or ideas?

  2. #2
    We have purposely
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    ChuChu Flamingo's Avatar
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    First course of action should be to make sure your cart contacts and mvs motherboard cartridge contacts are clean.

    I would recommend taking apart your mvs cartridge (opening it no more than a 45 degree angle) and using a white art eraser/Electrical Contact Cleaner+q tips on the connector.

    also clean your mvs cartridge slot as well. Most people fold a thin tshirt over a used credit card and spray it with rubbing alcohol/contact cleaner and insert/take out until the cloth comes clean. Just make sure you do it straight and not side to side to reduce the chance of a fiber grabbing a pin and bending it. Another way I like to do it is use a clean mvs cartridge and spray it with contact cleaner on the contacts and give it a few insertions and wipe it off until it comes clean.


    he spends hundreds on scarves, of course he's a fag and then ChuChu Flamingo preserved the aftermath in a plastic case making sure it wasn't exposed to unstable air
    You're just upset that you're too goddam stupid to understand the games and whiff infinites.

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    Thanks for the tips. It also happens with no cartridge inserted. I'm honestly not sure what is supposed to happen if nothing inserted, but I thought there may be just a Neo Geo logo perhaps.

    I tried 3 different carts, two legit and one multicart. I'll try to clean them and the cartridge slot, maybe something got in the slot itsself when I was wiring.

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    ChuChu Flamingo's Avatar
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    When nothing is inserted you should get a cross hatch pattern.



    he spends hundreds on scarves, of course he's a fag and then ChuChu Flamingo preserved the aftermath in a plastic case making sure it wasn't exposed to unstable air
    You're just upset that you're too goddam stupid to understand the games and whiff infinites.

  5. #5
    Divine Hand of the UniBIOS
    Razoola's Avatar
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    The problem given the error messages are in the bios area. Either the wiring of the mod is not good enough or the chip used is bad. Thats not an official unibios btw.
    THE UNIVERSE BIOS ( MVS / AES, and now also for CD )
    www.universebios.com. Also on facebook, please like http://www.facebook.com/UniverseBios.

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    Quote Originally Posted by Razoola View Post
    The problem given the error messages are in the bios area. Either the wiring of the mod is not good enough or the chip used is bad. Thats not an official unibios btw.
    Thanks for confirmation, I wasn't sure if it was legit or not.

    I'll poke at the wiring a bit (if I can somehow get the hot glue removed) with a fallback plan of getting a different board w/ a proper Unibios from you.

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    DANCE DANCE KARNOV!
    NeoTurfMasta's Avatar
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    Rip up the wiring and get one of these

    https://www.neogeofanclub.com/projects/neobiosmasta-og

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    Good idea. What's a hot glue removal technique - hair dryer + upside down motherboard and hope it drips off?

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    DANCE DANCE KARNOV!
    NeoTurfMasta's Avatar
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    Quote Originally Posted by falz View Post
    Good idea. What's a hot glue removal technique - hair dryer + upside down motherboard and hope it drips off?
    Not sure actually, just be careful when removing the wires. You'll need to keep a couple of those pads in good shape to solder to.

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