Video artifactys: can i use Lumafix in C64R?

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Don't Panic. Please wash hands.
  • Hi,


    my VIC 6569R3 cause some artifact on screen


    -Chekerboard pattern

    -irregualar switching from color screen to black and white screen.


    I'm using an SVideo cable in a modern LCD monitor.

    I know that this is caused by a mismatch between 40years old technology with modern technology and i just guess this is tipical for the 6569R3 because i have this issue with 2 different 6569R3 in 2 different boards (an original 250407 and the C64R).

    Can i use lumafix to correct this? Or i risk damaging the motherboard?


    Many thanks for any answer you can give me.


    PS: Can i suggest, in future relases to implement something like lumafix directly on the C64R?

  • -irregualar switching from color screen to black and white screen.

    That indicates that the colour carrier is off, which can almost not happen, as it's generated by a crystal. Only if the PSU you're using has extremely high ripple, it might have an impact on the oscillator or the PLL circuit that generates the other clock(s). Did you order the PSU with the board? If so, we can exclude that, and may need to look at other parts that are powered from the C64RMK2.

  • no, i bought the PSU from amazon, but not a cheaper one...

    ok, i undertand.


    I will just try by using another VIC in worst case, i will order a psu from you.


    Edit: i've applied the lumafix to the VIC. The video signal is perfect.

  • I also have a problem with the lack of colors on S-Video, but I noticed that when I put the plug into the monitor output, the color appears on s-video, after removing the plug it disappears again. I do not know what's going on.

  • 1. After connecting only the cable to the AV (DIN) output, the picture is colored.

    2. After connecting only the S-video cable, I have a black and white image on the screen.

    3. If I connect the S-Video cable to the TV and additionally connect the other DIN cable only to the computer, then the color appears on the S-Video output.


    C64R MK2 purchased last week.


    I can't explain it better, if it's still not clear then I will be home on Saturday to record a video.

    I do not officially report this as a bug, you can live with it. It may be the fault of the S-Video cable.

  • What you're showing is expected behaviour: S-Video contains two signals, a black-and-white Luma signal, and a separate colour channel. Your cable only has a single signal, and that's obviously only the Luma info.


    Sometimes there is enough colour information remaining in the Luma signal for a monitor to display colours, but the signal is really b/w only. By connecting an otherwise-unconnected long cable to the AV port, there is crosstalk between Luma and Chroma, which is obviously enough to catch the colour signal from the otherwise-black-and-white Luma signal. It does look like "magic", but has a simple explanation from the electrical engineering dept :-)


    Get a proper S-Video cable that will transfer both components of the picture, that will solve your problem.