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Voultar Mega Drive RGB Mod, made no difference.

Home Forums Repairs and Mods Voultar Mega Drive RGB Mod, made no difference.

This topic contains 3 replies, has 3 voices, and was last updated by  SRRAE 6 days, 12 hours ago.

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  • #28611

    SRRAE
    Participant

    I’ve installed the RGB mod but the result is no better than when I just removed the composite signal by isolating pin 6 on the CXA114.

    Just a couple of questions.

    On the photos on the writeup, when saying to cut 4 tracks, C103 doesn’t have a capacitor on. Is that standard for this board as mine has a capacitor there. Do I need to remove it?

    Also when it says cut the tracks for RGB, I removed the resistors at R17 R19 and R21 instead as that will also break the circuit, is that a viable way of doing it?

    Either way after doing this there is zero improvement over what it was before. Any help welcome.

    #29787

    BlueStinger
    Participant

    Avoid the motherboard as much as possible, stay away from the RAM, lift pins from the vdp directly, use shielded wires and ground them. Avoid the crystal oscillator as well and try to physically separate Sync and RGB lines as much as possible. Get your GND and +5V for the bypass at the voltage regulator and lastly, add some caps between +5V and GND near the vdp like shown here : https://www.retrorgb.com/genesis1rgbbypass.html
    I hope this helps !

    #29788

    TheCorfiot
    Participant

    Hi There

    The Resistors are not inine with the RGB lines they are Pullups between the RGB lines and the 5V rail.
    So basically the RGB signals in your case are still making their journey to the CXA chip

    You MUST Cut the Signals as advised, Carefull placement of the RGB Hookup wires to the Amp Board input is also crucial to reduce the Jailbars.

    #29829

    SRRAE
    Participant

    Hi TheCorfiot,
    This is the section in question. The R G B comes through the vias in the middle and the instructions suggest to cut the traces in the circled location. Instead I removed R17, R19, R21.
    From my basic knowledge (and I do admit it is basic) Wouldn’t that have just the same effect as either method results in the RGB signal being severed going right on the board in this picture?

    RGB Mod Cut trace

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