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Thread: Signal interference in CMVS with RGB and Component out.

  1. #1
    Edo Express Delivery Guy
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    Signal interference in CMVS with RGB and Component out.

    Repairing my CMVS and I've run into an annoying bug. It's not a big deal, but I'd like to fix it if possible.

    My Video out consists of:
    RGB through a AES style Din-8
    Component & S-video from a Neobitz encoder.

    RGB signals to the Din-8 go through a little trimmer pot and a 220uf cap as recommended by some members here, it looks excellent on my PVM and should work great on an OSSC when I get one.

    RGB lines have a separate set of trimmer pots added before they go into the NeoBitz encoder as I wanted to be able to adjust the component signal since straight from the Neobitz was a bit bright for my TV.

    To make this more clear, raw RGB lines from the motherboard are split, each going through a set of pots, one for RGB out, another for the Neobitz. It works well and I can adjust them independently.

    Problem I've noticed is when using RGB, the video gets much brighter when I unplug the Neobitz encoder. There is one plug going into the encoder that carries RGB+S 5v and G, and when I yank that plug out and don't send anything to the Neobitz the RGB feed gets much brighter.

    Is there a way I can somehow isolate the signals so the Neobitz isn't essentially sucking some signal strength when I'm not actually using it. I know I could add switches to the lines, but that's really annoying and I don't have any place to install them that doesn't require opening the CMVS to change them. I could probably ad a switch to just the 5V line going to the Neobitz, but I'm not actually sure if that would help, as I think it's more that the RGB lines are always connected, and I really don't want 3 different switches I have to flip just to use component vs RGB.

    I'm not too great with electronics, is there some better and more passive way I can do this?

    In the end it doesn't really matter that much, I'm already turning the RGB lines down a bit to go into my PVM or future OSSC anyways so the reduction in signal strength might not matter, but it bothers me and seems like there should be a better solution.
    -Finch

  2. #2

    Neo Alec's Avatar
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    The smarter members here probably know a workaround, but this is the main reason why I decided to go RGB-only for my latest CMVS

  3. #3
    Edo Express Delivery Guy
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    Well I guess in a way that's hopeful, because it means I'm not just missing some stupid detail because I'm an electronics noob.

    Id probably go full RGB if I had an OSSC, but this enclosure is already drilled for component and I already had the Neobitz and my home TV has component so it was a good option. Right now RGB is only for my PVM and a future upscaler. Seeing how many TVs no longer even have component I realize I should probably explore other options in the future.

    If I can ever get my hands on a NeoVGA (fingers crossed they make more of them) I would probably build a new CMVS with HDMI only. I like the idea of using an upscaler, but in the end, I REALLY like the idea of making a totally self contained system that doesn't require any external adapters or converters to plug into a modern TV.
    -Finch

  4. #4
    JammaNationX
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    One way to check if it's the power supply is to get power from a properly earthed(Bridged earth and logic ground) arcade power supply. If you get no interference there then it's definitely the power supply.

  5. #5
    Edo Express Delivery Guy
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    Quote Originally Posted by Xian Xi View Post
    One way to check if it's the power supply is to get power from a properly earthed(Bridged earth and logic ground) arcade power supply. If you get no interference there then it's definitely the power supply.
    What about the power supply would cause this? not strong enough? I've got a decently beefy one, 5v 3a Meanwell brick. I have a 5v 7a Apple TV powersupply I could probably wire up to test with too. unfortunately, I don't have a proper arcade PSU around.
    -Finch

  6. #6
    JammaNationX
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    Quote Originally Posted by Finch View Post
    What about the power supply would cause this? not strong enough? I've got a decently beefy one, 5v 3a Meanwell brick. I have a 5v 7a Apple TV powersupply I could probably wire up to test with too. unfortunately, I don't have a proper arcade PSU around.
    Lack of ground for the interference to disperse. You have to either find a better two prong supply that has better filtering or use a 3 prong one.

  7. #7
    Edo Express Delivery Guy
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    Mine is a 3 prong. It's this one here https://www.jameco.com/z/GS18A05-P1J...g_1940387.html
    -Finch

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