SNES RGB Buzzing + No Auto Switching

Discussion in 'Modding and Hacking - Consoles and Electronics' started by steocullen91, Feb 1, 2018.

  1. steocullen91

    steocullen91 Rising Member

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    So I bought a cheap snes RGB cable a while back and the picture had clipping on bright scenes with way too much contrast and when I tried it on an LCD it actually looked like a checkered image.

    So anyway I modified the cable myself and followed this http://members.optusnet.com.au/eviltim/gamescart/snespal.png

    I had to use 100ohm resistors instead of 75ohm and a 200ohm instead of a 180ohm. I also used pin 7 instead of pin 9 because I heared sync on luma gives a better image.

    Anyway I have audio buzzing at bright scenes even though I chained ground to every ground section on the scart and also it won't switch to AV automatically like they're supposed to. I checked all the wires and everything seems to look ok. Just no auto switch and buzzing in the audio. Any suggestions on what could be wrong?

    Literally followed that exactly except for pin 7 (luma) and the slightly different resistors I listed.

    Thanks.

    Ok so I found out my cable hadn't actually got 12v but actually had 2 GND cables. I changed it so the cable was 12v and just chained pin 5 and 6 together as they're both ground. Auto switch is switching as soon as I plug the SNES in now though even if it's powered off but it's setting the screen to 4:3 which is what I want. I don't mind too much about that switching thing when it's plugged in but I am still getting audio buzz.
     
    Last edited: Feb 1, 2018
  2. Pikmin

    Pikmin Resolute Member

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    From what I've found is that these cheap cables are not grounded, you will find that audio L and R just have a wire and no shield(which should be connected to ground) I've asked the same question, Ultron answered it.

    On my crappy scart cable I (only) have 8 wires.
    So 3 are used for RGB, 2 for L and R, 1 for +5V, 1 for Sync (on luma) and last one for GND

    Was the buzzing present when you had two separate GND?

    Pin 16 on the scart controls the mode - Composite in or RGB in
    Pin 8 controls the screen ratio - off, 16:9 or 4:3

    (Thanks to jaskamakkara)
     
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  3. steocullen91

    steocullen91 Rising Member

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    I have 9 cables in mine and I changed it back so there's no 12v but 2 GND again instead and it just had 5v for 16:9 for now. The buzzing is still there on brighter scenes but it's not as loud now with the 2 cables going to ground. I was actually told elsewhere to use a VGA cable to make the RGB since it has shielded cables. Only thing is I'd have to start over and make it again from scratch and the cable might be a bit wide near the consoles av port.
     

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