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Thread: swap KA2195 from VA1 MD2 USA w/ CXA1645 from Gen3?

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    Qirex RD Sports Talker AG Wolf's Avatar
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    Default swap KA2195 from VA1 MD2 USA w/ CXA1645 from Gen3?

    I've de-soldered the samsung video encoder from my VA1 NTSC Genesis Model 2 and the CXA1645M from my mono Genesis 3... Before I make this any more complicated for myself, is it possible to do a straight swap of the chips? I see blank areas for resistors and caps around where the KA2195 sits, and if I follow the same traces on the Gen 3 board from where the CXA1645 sits, there are components visible...

    Since I'm in the US, I seriously doubt my chances of finding a non-Samsung encoder chip in any model 2 I find... anyone have any insight?

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    YM3438 Master! ESWAT Veteran evildragon's Avatar
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    I have a US model 2 with a Sony chip...
    Customized Sega Genesis Model 1 - VA3. Energy efficient with buck converters instead of LM7805's.


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    Qirex RD Sports Talker AG Wolf's Avatar
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    then I hate you out of jealousy lol :P

    j/k All the Model 2's I've had my hands on over the past couple years have all had the Samsung chip unfortunately :/ And with the internet searching I've been doing, it seems like a model 2 with a Sony chip is a bit of a rarity here in the states

    Whatever the case, I'd still like to know if it's possible... though at this rate I'll probably find out myself before I get an answer here lol :P Nearly done wiring the bare chip so I can put it on the board

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    Hero of Algol kool kitty89's Avatar
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    As has been seen in some past discussions, some VA3s with CXA1645s can have oddly nasty output, possibly due to external components, but I'm not sure. (it's definitely TV specific as well) S-video mods avoid that though.

    The CXA1145 is rather common on many model 2s though tends to be worse than the same chip on model 1s. (again, I assume due to external components on the board -resistors/capacitors; generally it's darker and more saturated with possibly a bit more artifacting)
    Still fine for modding though. (both improved composite and S-video possible)


    The KA2195D has a different pinout than the other encoders, so you won't be able to do a simple swap, but need a bit of rewiring. (I think the CXA1145 and 1645 have the same pinout and MB3514 may be similar as well)
    6 days older than SEGA Genesis
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    Quote Originally Posted by evilevoix View Post
    Dude it’s the bios that marries the 16 bit and the 8 bit that makes it 24 bit. If SNK released their double speed bios revision SNK would have had the world’s first 48 bit machine, IDK how you keep ignoring this.
    Quote Originally Posted by evilevoix View Post
    the PCE, that system has no extra silicone for music, how many resources are used to make music and it has less sprites than the MD on screen at once but a larger sprite area?

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    Qirex RD Sports Talker AG Wolf's Avatar
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    yeah ive been looking at the data sheets for each chip:

    KA:
    http://pdf1.alldatasheet.com/datashe...NG/KA2195.html

    CXA:
    http://pdf1.alldatasheet.com/datashe...Y/CXA1645.html

    The only pins that look like they might be problematic are 5, 6, 8, 9, 10, 17, and 18... but I dont know if one sheet uses different terminology than another (SIN-Pulse vs X-Tal Osc, for example)... any idea of what pins I'd have to rewire? Do I need to add a crystal? do I need to add the other components which were present on the Gen3 board?

    edit: Alright, well it definitely didn't work by swapping it pin-for-pin. So I guess now I'm on the hunt to figure out what I need to do to make it work.
    Last edited by AG Wolf; 06-24-2010 at 12:41 AM.

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    YM3438 Master! ESWAT Veteran evildragon's Avatar
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    Customized Sega Genesis Model 1 - VA3. Energy efficient with buck converters instead of LM7805's.


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    Qirex RD Sports Talker AG Wolf's Avatar
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    yeah, see, you have components on the board at all these locations:

    C28
    C29
    C30
    C32
    R47
    R55
    R56
    R57
    L2
    L3
    And you seem to have some kind of jumper just below the left corner of the cartridge slot that I see no marking for on my board at all...

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    Sensato Kuro's Avatar
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    I too have tried swapping the KA2195 with a CXA1645 before. Like it's been said, pin for pin swap didn't work for me neither. Too bad cause I have a bunch of CXA1645 I've extracted from PS1s laying around. I was hoping to give a sweet s-video boost to these Genesis 2.

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    Hero of Algol kool kitty89's Avatar
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    Remember, even with the proper pin conversions, without proper buffering (caps+resistors of correct values and possibly other factors) and the TV used, you could have crappy looking CXA1645 video too, with worse "edge pixelization" than the Samsung chip. (the KA2195 also seems immune to rainbow banding, while all others may have it under certain conditions)

    However, if you're planning S-video on top of a replacement, then there's less to go wrong as you won't have luma artifacts to worry about. (both CXA1145 and 1645 will have chroma artifacts though, as slightly off shades every other pixel, at least for 320 wide resolution -that is obscured by blur and luma artifacts in composite video)
    6 days older than SEGA Genesis
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    Quote Originally Posted by evilevoix View Post
    Dude it’s the bios that marries the 16 bit and the 8 bit that makes it 24 bit. If SNK released their double speed bios revision SNK would have had the world’s first 48 bit machine, IDK how you keep ignoring this.
    Quote Originally Posted by evilevoix View Post
    the PCE, that system has no extra silicone for music, how many resources are used to make music and it has less sprites than the MD on screen at once but a larger sprite area?

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    So's your old man! Raging in the Streets zetastrike's Avatar
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    I must be really lucky because the first model 2 I picked up to examine at my game shop was a VA4 with the Sony chip. I'm guessing those are from '96-'97?
    Quote Originally Posted by A Black Falcon
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    No, it's unbiased analysis. The only fanboyism is people who claim that Hyperstone Heist and Bloodlines are actually as good as their SNES counterparts.
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    Hero of Algol TrekkiesUnite118's Avatar
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    This thread at GameSX might shed some light:

    http://nfggames.com/forum2/index.php?topic=3962

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