N64 RGB Mod - Poor quality image

Discussion in 'Modding and Hacking - Consoles and Electronics' started by fathertime, Jul 16, 2011.

  1. fathertime

    fathertime Rapidly Rising Member

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    maybe someone can help..

    I have a first edition USA N64 modded for RGB and used on a PAL TV that supports 60hz NTSC RGB.


    The problem is
    -horrible horizontal lines on the top 1/3 of the screen that "flicker"
    -a X pattern through all the graphics.
    Have a look at the attached image.


    I modded this almost 15 years ago - It's modded with the same method as per mmmonkeys RGB "Method 2" on this page http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb.htm

    For the RGB cable, I've tried both my custom PAL SNES RGB cable and PAL Gamecube cable.

    So... do I just need a different N64 specific RGB cable? Is the console just too old? Is my mod too old skool and I should do a different RGB mod?

    I used to have a custom N64 RGB cable and as far as I recall it looked ok on my CRT, but that was 10 years ago and I don't have the cable anymore.. That's why I'm thinking I need to get an N64 RGB cable compatible with mmmonkeyes Method 2 - but where to buy?

    -----
    Update: Added more photos.
    -SNES RGB PAL Cable with 75ohm resistors to ground on R, G, B and Composite Video
    -GameCube RGB PAL Cable with 220uF Capacitors in series on R, G & B (and 75ohm resistor to ground and 220uF capacitor in series on Composite Video)

    According to http://gamesx.com/wiki/doku.php?id=av:nintendomultiav those cables are perfect for SNES/Cube however for the N64 there is no info.. "N64 RGB Cable components will depend on the mod performed".

    Hmm, are either of those SNES or Cube cables I have compatible with mmmonkeys Method 2 mod?
     

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    Last edited: Jul 16, 2011
  2. bobzee

    bobzee [undefined]

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    Have you tried it on another TV and does it look the same?
    Some LCD's are really picky about sync errors.

    Check that the N64's RF shield still in place, and check the RGB wiring in the console to make sure it's still good.
     
  3. fathertime

    fathertime Rapidly Rising Member

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    Hi bobzee - RF Sheild is in place and RGB mod wiring is still good according to the multimeter.

    It may well be the TV.. TV is a 50" Plasma model PS50C680 - I actually don't have any other TV to test on though.

    The first post is updated with the RGB cables I have available to me. I guess the question is to ask does anyone know if either of these cable should be giving a good image considering the mod performed? (right now the image is poor with either cable).
     
    Last edited: Jul 16, 2011
  4. retro

    retro Resigned from mod duty 15 March 2018

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    Have you checked the RGB outputs, sync output, switching output etc. to ensure they're all in range?
     
  5. Oldgamingfart

    Oldgamingfart Enthusiastic Member

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    Yes I think it might be worth trying to disconnect (and separate) the resistors on the RGB and Composite lines (SNES cable), so there is a direct connection from the N64 to the SCART pins.

    Also check the grounding for the RGB lines (pins 5, 9, 13, and 17 on the diagram >>here<<). Maybe 'tie up' all the ground points to the SCART outer shield (aka Pin 21), back to the N64 ground.
     
    Last edited: Jul 17, 2011
  6. fathertime

    fathertime Rapidly Rising Member

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    Cheers folks for the replies. I'll re-mod and get a new cable.

    It seems the whole N64 RGB mod topic is a bit of a mess to be honest... several different mod methods for both the N64 board and the cable itself. Then most of the board mods out there don't even say what is the correct cable to use after the mod.

    I wish there was a just one guide for "the Ultimate n64 RGB mod with cable". Maybe I'll try this one first http://www.mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb_new.htm and use the cube cable.

    Will let you know how it goes!
     
  7. Bad_Ad84

    Bad_Ad84 The Tick

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    Just got my french N64 through the post and ended up with exactly the same problem you have.

    The X pattern through all the graphics really kills the picture.
     
  8. sanni

    sanni Intrepid Member

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    Try using the composite sync instead of composite video as sync signal. Maybe that will help.
     
  9. mdmx

    mdmx Familiar Face

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    I had the X pattern problem with my N64 and Super NES RGB cable aswell . I solved it as follows:

    open the Multi AV connector at your RGB cable, remove the wire from pin 9 (Composite Video) and solder it to pin 7 (S-Video Y). This mod might not work with a flat screen TV.
     
    Last edited: Jul 18, 2011
  10. Lum

    Lum Officer at Arms

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    Yup I really need to find someone in the states who mods RGB cables. Perhaps a trick like that might get this here Japanese Saturn to correctly trigger RGB mode, and remove my Genesis 2 cable's jailbars.
     
  11. Mamejay

    Mamejay Robust Member

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    I agree with Sanni. I had the same problems with a PCEngine RGB mod I did when using Composite out for my CSYNC. Onces I changes it over to CSync the x pattern disappeared.
     
  12. Bad_Ad84

    Bad_Ad84 The Tick

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    Update:

    I also switched to C-Sync and it resolved all of my N64 quality issues.

    My scart lead didnt have a wire connected to Pin 3 (n64 side). So I decided to cut the trace going to pin 9 (composite video) and connect pin 7 (C-Sync) of the S-RGB A chip to the now disconnected pin 9.

    This allows me to use my unmodified RGB scart cable with the N64, with C-Sync on pin 20 (scart side).

    I obviously wont get composite out of it anymore - But if I wanted composite I wouldnt have gone to all the trouble of getting a RGB moddable console in the first place.
     
    Last edited: Jul 24, 2011
  13. fathertime

    fathertime Rapidly Rising Member

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    Guys, thanks for all the advice.

    A couple of things -

    First of all, I picked up a retro 29" Sony Trinitron CRT. This thing is HUGE and weights a ton so I can't get it into the house just yet. It's out in the shed for now but I hope to test it soon and I'll let you know if it looks good on a CRT.

    The second thing purchased is the 'Sync Strike', 'cga2vga Scaler' and 'SLG3000' - I'm sure a lot of you guys know about this set of products but apparently it is supposed to take in a Scart RBG cable, clean up the composite sync to a clean c-sync, output to VGA and then the SLG3000 adds nice scanlines on a 50" plasma! Can't wait for this package to arrive.

    Thirdly - also still waiting on the THS7314 for the RGB amp mod but have all the other bits ready to go.

    If after all of this, the image still looks poor, then I'll consider your advice on the PCB c-sync to composite mod. From past experience though, when I cut a trace it will be destroyed forever ;)
     
    Last edited: Jul 24, 2011
  14. Bad_Ad84

    Bad_Ad84 The Tick

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    Last edited: Jul 24, 2011
  15. link83

    link83 Enthusiastic Member

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    Was there a 75ohm resistor to ground on Composite video inside the SCART cable? If not thats likely the reason for the poor sync signal since all PAL N64's need this.

    Also its worth knowing that C-Sync is only present on specific N64 motherboard revisions, so its not a solution that can be used on all N64's.
     
  16. Bad_Ad84

    Bad_Ad84 The Tick

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    There wasn't originally a 75ohm resistor in the cable, I did add one. But, it made no difference either way.

    And which RGB moddable N64's dont have C-Sync available? the NTSC ones? I was under the impression all RGB moddable N64's have C-Sync. The french one certainly does as I am using it.

    I thought pin 14 on the VDC-NUS was C-Sync?? which is on the NTSC console.
     
    Last edited: Jul 24, 2011
  17. link83

    link83 Enthusiastic Member

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    Hmm, a 75ohm resistor to ground (Not in series) should have fixed it, glad you got it sorted anyway :nod:

    NUS-CPU-04 is an RGB moddable NTSC N64 that has C-Sync output removed, but its also absent from all subsequent NTSC motherboard revisions as well (Although they are not easily RGB moddable either) Also, no PAL N64s (French or European) have C-Sync output available as standard either.

    For anyone interested in more info please see my thread about N64 motherboard revisions here:-
    http://forums.benheck.com/viewtopic.php?f=5&t=27684

    <EDIT>The VDC-NUS chip is only present on the first four NTSC motherboard revisions and the French specific N64 motherboard. Pin 14 is C-Sync, but you should not use it directly as it needs to be buffered - its these buffering components which are removed on the NUS-CPU-04 motherboard revision.
     
    Last edited: Jul 24, 2011
  18. Bad_Ad84

    Bad_Ad84 The Tick

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    Your post on that link about the NUS-CPU-04 says "The traces for C-Sync output still remain on this revision but the SMD components have been left off the board as a cost cutting measure"


    This is the same as what was on my french N64 - all the components connecting it to Pin 3 were missing. I just took it directly from the VDC-NUS or S-RGB A. Which is the same method I have read for the Snes jr RGB mod.
     
    Last edited: Jul 24, 2011
  19. link83

    link83 Enthusiastic Member

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    On the French N64 these missing components were not for C-Sync - some are for RGB, and the ones connecting to Pin 3 were for +12V for SCART switching, but since Nintendo left off the components for RGB they removed +12V as well.

    As for connecting directly to the VDC-NUS chip, please see above post edit.

    <EDIT>On the French N64 you want to take C-Sync from the 'S-RGB A' chips C-Sync output, which is on Pin 18 as shown by DarthCloud here:-
    http://www.assemblergames.com/forums/showthread.php?t=33136
    This C-Sync is buffered by the S-RGB A chip and is usable, the C-Sync input on the other hand should not really be used directly. I am in the process of writing a new GameSX SNES Jr RGB mod guide which will also mention how to get S-Video and C-Sync as well.
     
    Last edited: Jul 24, 2011
    Bad_Ad84 likes this.
  20. Bad_Ad84

    Bad_Ad84 The Tick

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    I just saw missing components, so didnt even bother tracing it as I wasnt going to use that pin anyway (not connected in my cable) :)

    What components are required for the buffering? and is this only when tapping from the VDC-NUS or does it also apply when coming off the S-RGB A chip?

    I took it from S-RGB A (as its there, why add another amp for RGB), which is exactly the same as the snes jr RGB mod. However, we all know guides can get it wrong.

    But even if you have to buffer from VDC-NUS - that still means C-Sync is available on all RGB n64's, doesnt it

    Edit:

    You answered most of this post in your above edit. I will change my C-Sync over to pin 18 and will keep that in mind when my Snes JR arrives.

    Thanks for you input, as always :)
     
    Last edited: Jul 24, 2011

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