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Thread: Strange mod to a Sega CD 2

  1. #1
    Bell (Level 8)
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    Default Strange mod to a Sega CD 2

    I've taken apart my fair share of Sega CD 2 and I happened to have one in pieces today to fix a sticky eject button when I noticed something I never saw in the last few Sega CD. Here's the picture I took:

    One chip is 7474 , and another is 7404 hex inverter. There are 5 wires total: red and black are obviously +5v and ground and the other 3 I haven't identified. Any idea what this board is for? A Mod chip? A bug fix? I could try and rip the board off and trace the circuit on the bottom (it's held by a double sided foam tape)
    Another day, another dollar... wake me when it's payday.
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  2. #2
    Bell (Level 8)
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    Looks like a fix of some kind. The diagram appears to be nothing more than to delay and invert the signal. here's a quick diagram I made:
    Another day, another dollar... wake me when it's payday.
    still playing games

  3. #3
    Pac-Man (Level 10) omnedon's Avatar
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    I have another that looks just like that one. Must be a factory fix.
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  4. #4
    Great Puma (Level 12) Custom rank graphic
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    Was it a working unit or did you just take it apart to have a peek. I wonder if it's worth looking at my busted ones to look for the mod. Maybe it's not there and that might help me out.
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  5. #5
    Bell (Level 8)
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    Mine was working when I took it apart, I had some trouble with the eject button. And I don't think this would help with your broken Sega CD, it appears to just shift the data half a clock and invert them. Possibly because of a chip revision required that at one point.
    Another day, another dollar... wake me when it's payday.
    still playing games

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