neogeo

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  • May 23, 2018 at 6:45 PM #21827
    BuckoA51
    Keymaster

    would the 5v be dangerous should I add a resistor?

    May 24, 2018 at 9:56 AM #21832
    BuckoA51
    Keymaster

    Yes, using the resistor is highly recommended. Unlikely that you’d fry your unit feeding it TTL but it’s somewhat out of spec and could cause damage over time.

    May 24, 2018 at 10:32 PM #21857
    Anonymous
    Inactive

    I’m curious – it looks like the audio is routed via RCA cables, and not going through the SCART connector? How will you handle the audio transmission?

    May 24, 2018 at 10:39 PM #21859
    nmalinoski
    Participant

    You should be able to get sync normally from composite or luma, right?

    Audio can be added into SCART with an injector/breakout shim, assuming it’s fully wired, or can be routed around the OSSC (which would be necessary for <=1.5 OSSCs anyway.

    May 25, 2018 at 1:09 AM #21866
    BuckoA51
    Keymaster

    Okay I will try that

    June 1, 2018 at 4:25 AM #21937
    BuckoA51
    Keymaster

    Just says no sync

    June 1, 2018 at 5:29 PM #21950
    Anonymous
    Inactive

    Looking at the mod instructions, my mind immediately goes to the part about cutting traces. You probably already have, but the first place I would look is making sure only the traces that are supposed to be cut have been cut, and that the cut traces are completely severed. Mutlimeter continuity check on the cut lines to make sure there is no continuity, and multimeter check on any nearby lines to make sure they still have continuity.

    June 1, 2018 at 5:42 PM #21951
    BuckoA51
    Keymaster

    Not sure why its off

    June 1, 2018 at 9:53 PM #21955
    Anonymous
    Inactive

    Check for continuity between the pin with white wire/black tape to each of the pins with the yellow wire bridge? (Probably implied that you already did, but just double checking) Also, check for continuity from each of the 3 pins to ground?

    Csync should go to SCART pin 20. But, you won’t get continuity from end to end if there are resistors, caps, etc along the path. You may have to open visually trace it out.

    June 2, 2018 at 6:50 PM #21964
    BuckoA51
    Keymaster

    ill recheck

    June 2, 2018 at 11:37 PM #21970
    BuckoA51
    Keymaster

    AV/ Yellow RCA at the same time

    June 3, 2018 at 10:25 AM #21974
    paulb_nl
    Participant

    However, only the CSYNC/Resistor/White wire will have continuity with the ground.

    CSYNC should not have continuity to ground (when the RGB cable not connected). Redo the mod until its not shorted to ground.

    June 3, 2018 at 5:58 PM #21977
    BuckoA51
    Keymaster

    Maybe i’m testing this wrong? Bad chip?

    June 3, 2018 at 7:26 PM #21984
    paulb_nl
    Participant

    So with CSYNC continuity to ground you mean 0 Ohm resistance right?

    To make sure the CSYNC RGB cable actually works, try bridging the CSYNC pin you cut back to the composite video pin to see if you get sync with the OSSC.

    June 3, 2018 at 7:45 PM #21985
    BuckoA51
    Keymaster

    thank you

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