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Donkey Kong PCB Video/Audio Mod

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  • Donkey Kong PCB Video/Audio Mod

    There's very little mention of this conversion online, the DK PCB has provisions to swap between negative/positive video and onboard/external sound amplification.
    The DK PCB was normally paired up with a Sanyo EZ20 monitor which uses negative video and has an onboard sound amp.
    If you want to plug a DK PCB into a Jamma cab you need a special Jamma adapter that inverts the video and amplifies the audio.
    I'm repairing some boards that need to be able to be plugged into both an original Nintendo cab as well as a Jamma cab.
    Fortunately the PCB is designed to be able to do this and you just need to populate it with the missing components.

    Below is what you need to do to mod a board.

    There's two sections on the CPU board where there are a number of unpopulated component locations.
    One is video and the other is sound.

    Video section...



    Sound section...



    The yellow jumpers are where a 10 way DIP switch needs to be fitted to swap between outputs.

    This is what it looks like when modded.





    The video transistors should be 2SC1815's but they're not commonly available here so they have been substituted for 2N3904's, they have a different pinout so the centre and right legs (Collector-Base) need to be swapped around.
    It uses an MB3712 amp which can be substituted with an MB3713 flipped around (reverse pinout).
    The correct sized 10K volume pot is also not commonly available here so I made a small riser/adapter board to in a standard trimmer pot (a 24mm pot could be remotely mounted somewhere off the board if desired), VR3/VR3/VR5 adjust the video bias.
    All the component values are marked on the board for convenience.
    The DIP switch in the last image shows the correct settings for a Jamma cab (onboard sound amplification and positive video signal).
    I did this conversion today and it's tested and working fine.
    Last edited by Kaizen; 23rd July 2018, 08:11 PM.
    Namco Starblade - Taito Cocktail 14" x 3, 20" x 2 - NZ SI PtII Upright - Chase HQ DX, Taito Top Speed - Taito Grand Champion - Taito Safari - LAI SI Head to Head Cocktail - SI Cocktail Clone x 2, Pong Clone x 3

  • #2
    Seriously your knowledge and skill is just crazy, love your work mate.
    Donkey Kong build - https://www.aussiearcade.com/showthr...-replica-build

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    • #3
      Amazing work!
      SEGA love: | Nintendo love:
      PC Engine love: | Latest retro finds:

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      • #4
        You can do the same on a DK Jr board as well. There's an old repair log from several years ago documenting it.

        Good work and thanks for sharing

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        • #5
          Yeah I found two very old posts which lead me to look into doing it.
          Nothing recent which is why I thought I'd should do a thread about it.
          Namco Starblade - Taito Cocktail 14" x 3, 20" x 2 - NZ SI PtII Upright - Chase HQ DX, Taito Top Speed - Taito Grand Champion - Taito Safari - LAI SI Head to Head Cocktail - SI Cocktail Clone x 2, Pong Clone x 3

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          • #6
            Originally posted by Kaizen View Post
            Yeah I found two very old posts which lead me to look into doing it.
            Nothing recent which is why I thought I'd should do a thread about it.
            Good on you mate. I love reading these threads and your enthusiasm. Wish I still had that spark.

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