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  1. #1
    Timid Neo Newbie
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    MV-1AX COLOR RAM BANK0 ERROR

    Hey ya'll. Was reflowing some chips on my neo geo mv-1ax and I accidentally wrecked a connection somewhere. I now get this Error "colour ram bank0 error: Address 00400000 write AAAA read AA2A" I've been checking around with my multi meter and I can't seem to find anything. Anyone have any clue how to go about this? Thanks!
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    drunk downunder!
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    If you can pay for my neck surgery to read it I might be able to assist.



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  4. #4
    Angel's Love Slave
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    Converting the hex values for the 2nd byte to binary you can see its testing with the AA bit pattern, and you are missing the upper most data bit. Find the color RAM and follow its connection for the upper most data bit.
    AA = 10101010

    2A = 00101010
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    Timid Neo Newbie
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    Quote Originally Posted by GadgetUK View Post
    Converting the hex values for the 2nd byte to binary you can see its testing with the AA bit pattern, and you are missing the upper most data bit. Find the color RAM and follow its connection for the upper most data bit.
    AA = 10101010

    2A = 00101010

    Thanks! I found the palette chips. they're RAM7 and 8 on my board. I was checking around them with the multi meter and I found that the 8 bottom pins on both connect together and go to the gpu, which i think is the 8bit bus. looks like the other connection is to V9 and V8. not sure about those. Sorry, i'm pretty new to this. I made a drawing for what I've figured out so far. I've found a few pinouts sheets, like the cpu but I can't seem to find one for the palette ram. Also I'm running the default bios right now.
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  6. #6
    Angel's Love Slave
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    Could be RAM 5 or RAM 6 as those are connected to the GPU there too. I think the ram that sits at 00400000h is palette RAM - I am just not sure where the palette RAM is on that model. I would just check which of those RAM chips have a missing upper bit connection.

    Pin 19 on the 62256 type chips is the upper data bit. What specifically did you reflow btw, because that's going to provide a clue probably.
    Last edited by GadgetUK; 09-30-2017 at 01:18 PM.
    My YouTube channel contains some MVS repairs and stuff:-
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