Help! Sega Master System 2 RGB mod - no Sony chip?

Discussion in 'Modding and Hacking - Consoles and Electronics' started by cookie, Mar 30, 2013.

  1. RetroSwim

    RetroSwim <B>Site Supporter 2013</B><BR><B>Site Supporter 20

    Joined:
    Dec 10, 2012
    Messages:
    605
    Likes Received:
    26
    The SCART connector should open up pretty easily, the components might be living in there...

    Just unscrew the collar around where the cables come out, and the casing should open up like a pizza box.

    Edit: I should refresh before I post. omp is on the money here. :)

    There's no reason the Master System should look bad, it's going to be down to the cable.
     
    Last edited: Apr 1, 2013
  2. APE

    APE Site Supporter 2015

    Joined:
    Dec 5, 2005
    Messages:
    6,417
    Likes Received:
    141
    The only thing that makes the cable "compatible" is that the RGB+SYNC lines are hooked up from the DIN connector to the SCART side of things. Caps, no caps; most TVs are pretty tolerant of bullshit you throw at them.

    Having the caps inside left alone was probably a good idea. I'm willing to bet there are extra resistors inside the SCART cable that aren't necessary.
     
  3. RetroSwim

    RetroSwim <B>Site Supporter 2013</B><BR><B>Site Supporter 20

    Joined:
    Dec 10, 2012
    Messages:
    605
    Likes Received:
    26
    That seems like a pretty big generalisation...?

    Having the correct combination of resistors and capacitors can be the difference between working and not working, or the difference between perfect and banding or loss of contrast.

    Some TVs might have in-built circuitry to deal with wrong DC bias or high/low attenuation, but I don't think you should bank on it.
     
  4. retro

    retro Resigned from mod duty 15 March 2018

    Joined:
    Mar 13, 2004
    Messages:
    10,354
    Likes Received:
    823
    Resistors in SCART leads are generally to pull signal voltages down to the correct level for what they're intended, e.g. switching.
     
  5. omp

    omp Familiar Face

    Joined:
    May 22, 2011
    Messages:
    1,017
    Likes Received:
    9
    I was thinking when the OP was talking about blue being stronger, I wonder if the cable has had "odd" (to each other) resistors installed? IE 100ohm, 75ohm, 100ohm or the like?

    It is hard from my point of view as (mentioned previously) I use a RGB-component converter and I think they may hide a few sins. As mentioned I left the caps out of the console this time and I didn't notice any real difference.

    EDIT

    There is a possible error in MMMMonkeys guide. If you refer to the Sega manuals (schematics) they all have a 75ohm resistor out of pin 20. Apparently the official cable had the 75ohm resistor as well. Could this be a problem?

    But according to the CXA1145 datasheet there is just the 1 75ohm resistor so NFI.
     
    Last edited: Apr 2, 2013
  6. cookie

    cookie Active Member

    Joined:
    Jul 11, 2012
    Messages:
    42
    Likes Received:
    0
    Hi Guys,

    At work at the moment but just a quick update. Before tearing the cable apart I thought it'd be worth contacting the seller to see if they could provide any info. I presented the following question:

    Response was as follows:



    So it sounds like the lead does not contain the capacitors? And just the one resistor.

    Cheers
     
  7. retro

    retro Resigned from mod duty 15 March 2018

    Joined:
    Mar 13, 2004
    Messages:
    10,354
    Likes Received:
    823
    To be fair, it's really hard to do your fault finding for you without so much as a picture. You really need to get some photos of your mod and preferably the SCART plug, too.

    The first thing to check would be that the RGB levels are all to the correct SCART specification.
     
  8. omp

    omp Familiar Face

    Joined:
    May 22, 2011
    Messages:
    1,017
    Likes Received:
    9
    Le' fuck?

    Pin 16 is something to do with RGB switching (and should be around 180ohms according to Viletims site), if it has no other components in the cable, then I think the problem is solvered.
     
  9. MangledLeg

    MangledLeg Peppy Member

    Joined:
    Jul 11, 2010
    Messages:
    353
    Likes Received:
    4
    Having another stock console will also help - it'll help rule out if the issue is to do with your mod or the cable.

    But like the others have said, some shots of the mod, cable and signal output on your TV could help an awful lot.
     
  10. retrotech

    retrotech Member

    Joined:
    Mar 24, 2013
    Messages:
    14
    Likes Received:
    0
    MB3514 strange rgb problems

    hi guys
    I've been trying to (with varying success) add a female scart block to get rgb out of the MB3514 on a master system II.
    I've been doing all the soldering on the rear of the board using schematics and pics i've found or a multimeter to tap points for each leg that needs to be connected
    Composite is fine, audio is working and when connected properly (220uf caps and 75 ohm resistors) it does seem to pop into rgb (no pixelation) but the colours are out (the sega logo is yellow), and there is banding in the colours...
    Anyone got any ideas? i've packed away for tonight but will get some pictures over the weekend and maybes make a little guide if i get it working as it should.
    This is my first MB3514 mod but have done a fair few with the sony chip but this ones got me a little puzzled.
    Thanks in advance
     
    Last edited: Sep 11, 2013
  11. ApolloBoy

    ApolloBoy Gutsy Member

    Joined:
    Sep 22, 2011
    Messages:
    425
    Likes Received:
    0
    Maybe your TV isn't properly switching over to RGB?
     
  12. synrgy87

    synrgy87 Well Known Member

    Joined:
    Jul 12, 2012
    Messages:
    1,769
    Likes Received:
    20
    or you've wired the colours wrong?
     
  13. retrotech

    retrotech Member

    Joined:
    Mar 24, 2013
    Messages:
    14
    Likes Received:
    0
    TV is def switching to rgb and yeah i was thinking colours are wrong so double checked, will get it out tomorrow and get some pics
     
  14. synrgy87

    synrgy87 Well Known Member

    Joined:
    Jul 12, 2012
    Messages:
    1,769
    Likes Received:
    20
    i unwittingly done that with a retro duo i was RGB modding got the right at the chip but somehow managed to get it wrong at the SCART end was scratching my head for a few days till i decided to pull the scart connector apart and check it, felt a bit dumb lol
     
  15. retrotech

    retrotech Member

    Joined:
    Mar 24, 2013
    Messages:
    14
    Likes Received:
    0
    yeah im pretty sure once i look at it with fresh eyes ill spot something silly lol
     
  16. APE

    APE Site Supporter 2015

    Joined:
    Dec 5, 2005
    Messages:
    6,417
    Likes Received:
    141
    The N64 has some very interesting changes when you swap red and green. At least in Diddy Kong Racing.
     

Share This Page