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Thread: MV-1AX COLOR RAM BANK0 ERROR

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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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    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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    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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    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 12:18 PM.
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    Actually another one of my boards on the bench, same model, has this exact issue other than the WRITE being different. I replaced rams 8 and 7 and traced every single one of those traces for continuity which tests fine. Im curious my self if rams 5 or 6 are actually color rams I have a few spare rams if i get around to it i might swap them LOL. I was told by someone I was working on that board with that 8 and 7 are pallets. Im gonna start subbing this thread :P

    *edit* ended up replacing 5 and 6 but i still get the same error (shurg)
    Last edited by Geekman1222; 10-01-2017 at 12:10 AM.

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    I re-flowed RAM7 and RAM8, as well as the PAL1 and PAL2. At first I thought it was the chips labeled PAL (for Palette RAM) but then I read that these are program chips. Of what I have no clue but I checked them and I can't find any shorts. While searching for more info I stumbled upon another Thread on a German forum with the same problem. On there I found this picture of the logic. http://www.imgbox.de/users/Merl/Colo...ult_CY6264.jpg. I think I get the gist of it and I followed all the lines, but none of them were shorted. I also checked the U8 and U9 connections according to this picture http://www.imgbox.de/users/Merl/P7280565.JPG everything checks out there too. I'm at my wits end on this one. I've ordered new chips as a last ditch effort. I was wondering though, Looking at the logic pic would you be able to determine which pin is the faulty one? Might try bridging it if I know which one to focus on. Thanks for the help so far btw.

  9. #9
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    Quote Originally Posted by Cyberosis View Post
    I re-flowed RAM7 and RAM8, as well as the PAL1 and PAL2. At first I thought it was the chips labeled PAL (for Palette RAM) but then I read that these are program chips. Of what I have no clue but I checked them and I can't find any shorts. While searching for more info I stumbled upon another Thread on a German forum with the same problem. On there I found this picture of the logic. http://www.imgbox.de/users/Merl/Colo...ult_CY6264.jpg. I think I get the gist of it and I followed all the lines, but none of them were shorted. I also checked the U8 and U9 connections according to this picture http://www.imgbox.de/users/Merl/P7280565.JPG everything checks out there too. I'm at my wits end on this one. I've ordered new chips as a last ditch effort. I was wondering though, Looking at the logic pic would you be able to determine which pin is the faulty one? Might try bridging it if I know which one to focus on. Thanks for the help so far btw.
    HAH i made the same mistake socketed them and put in actual rams in its place LOL found out that was wrong. I was just searching through the forums again for info on color ram errors since mine is still sitting on the bench no luck yet. Best of luck

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