Dreamcast RGB video problem

Discussion in 'Sega Dreamcast Development and Research' started by jake74, May 13, 2013.

  1. jake74

    jake74 Rising Member

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    Hello all,

    I have a V0 Japanese DC that's chipped, and I've owned and played since release.

    Last week, I turned the DC on (it's been sat in the same place on the shelf for months, and been played) but was met with a black screen, with faint white ghosting around the Dreamcast text on boot, then menu items. Sound works fine

    Using a yellow/red/white AV cable produces full colour picture, but switch back to the official RGB SCART lead, back to black pic with white ghosting.

    Any ideas what's causing this? I need RGB SCART on my DC!

    Any help much appreciated.
     
  2. dc16

    dc16 Dauntless Member

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    Your video cable is broken.
     
  3. jake74

    jake74 Rising Member

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    I tried two different SCART RGB leads. Both with the same problem.
     
  4. darcagn

    darcagn Site Supporter 2013, Site Supporter 2014

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    Very unlikely. The video signals for a SCART cable are red, green, blue, and sync. There is no luminance (black/white) wire. If the red wire were broken, there would just be no red part of the picture. Same for green and blue. If all of them were broken, then there would be no picture at all since white is generated by R+G+B. If the sync wire were broken, no picture would appear either.




    jake74, unfortunately it sounds like something more serious is going on. :(
     
  5. Bad_Ad84

    Bad_Ad84 The Tick

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    Picture of what it looks like would help
     
  6. jake74

    jake74 Rising Member

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  7. synrgy87

    synrgy87 Well Known Member

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    edit: before you do that check your tv settings for the scart input and make sure its set to "RGB" and not "s-video" or "composite" or even "auto"

    if there's caps in the scart cable for RGB try removing them looks like its getting sync but not strong colour signals - i could however be wrong but thats just what it looks like to me. also check the grounds in the scart cable too.
     
    Last edited: May 15, 2013
  8. jake74

    jake74 Rising Member

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    Checked caps, replaced one, still the same.

    So I tried another SCART LEAD.

    The same black screen happened with an official DC SCART lead.
     
  9. synrgy87

    synrgy87 Well Known Member

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    is the AV port at the back of the DC dirty or damaged?

    have you tried another TV ?
     
  10. jake74

    jake74 Rising Member

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    Synrgy, the TV is not the problem. It's rocking my Wii, PS2, PC Engine, PCE Turbo Duo, Jap MD and Jap switched 'Cube all fine.

    Have tried cleaning the AV port, no joy.
     
  11. synrgy87

    synrgy87 Well Known Member

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    have you tried messing with the tv scart input settings(if it has any) ? it could be auto detecting the input wrong eg "thinking" that its s-video input via scart instead of RGB.

    only other thing i can think of is removing the capacitors from the cable on the rgb line as they may not be needed by your tv. one of my LCD tv's doesn't like RGB scart with the caps on a sega master system but is fine with other consoles.(just an example)

    other than that, try a VGA box or stick with composite. or buy another DC
     
  12. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    The last post of the thread you linked to:

    You should try a non-scart output just to see if it fixes it.
     
  13. jake74

    jake74 Rising Member

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    See my first post.

    "Using a yellow/red/white AV cable produces full colour picture, but switch back to the official RGB SCART lead, back to black pic with white ghosting."
     
  14. synrgy87

    synrgy87 Well Known Member

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    just another thought, is your DC scart cable a pal one? or is it a japanese rgb one?

    i dont know if the japanese DC has a differently wired AV port (dont think so) but japanese RGB cables are differently wired than pal Scart.
     
  15. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Then it's either the scart cable(s) or the related pins on the av port that are broken. You could try another scart cable if you ahve access to one, as it fixed the issue in the quoted similar case.
     
  16. jake74

    jake74 Rising Member

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    Will try with a different TV tonight. The current TV (Sony Trinitron) was playing the DC fine previously. It's auto detect, so I can't push any buttons.

    As I said, the DC used to work, so removing caps shouldn't make a difference. Also, not tempted to open a barely used official DC lead just yet.

    Not tried VGA yet, but it's not a solution, as the Sony Trinitron doesn't have VGA…
     
  17. jake74

    jake74 Rising Member

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    Tried both JAP and PAL scart leads, same effect.
     
  18. jake74

    jake74 Rising Member

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    As mentioned early on in the post, tried another SCART lead. So yes… I think something's up with the AV port…
     
  19. synrgy87

    synrgy87 Well Known Member

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    the reason i mentioned VGA is because it uses the same pins for RGB as scart does so you could rule out an issue with the console and av socket.

    have you opened the console to check inside? nothings shorting or damaged?

    just throwing out suggestions at this stage
     
  20. lord_raymon

    lord_raymon Active Member

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    Sorry if this thread is old but I've been researching this problem ...

    If you have black screen it is because your TV does not like 12V on pin 8 of SCART, using 5V will run smoothly :)

    [​IMG]
    I have opened my cable connector and swapped the cable connected at pin 4 to pin 5, now it works in all my TVs.
     
    Last edited: Aug 24, 2016

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