3DO 240p output - VP536A encoder

Discussion in 'Modding and Hacking - Consoles and Electronics' started by airs, Feb 6, 2015.

  1. airs

    airs Spirited Member

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    3DO 240p/480p output - VP536A encoder

    I'm looking for a way to force 240p or 480p output for the 3DO. I have a Goldstar console with a VP536A. I've gone over the only technical document I could find for the chip (here) and I'm wondering if setting CTRLB1 high (pin 52) would have the desired effect. I don't have a ton of experience with circuits - it looks like pin 52 is pulled low so would I need to lift it off the board and connect it to a voltage source to set it high?

    Table from the pdf linked above:

    [​IMG]
     
    Last edited: Feb 6, 2015
  2. breech

    breech Member

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    I have no experience with that console but from the data posted CTRLB1 is internally low so you would need to apply the high level to the pin and probably lift it from the pcb too. If the B varient (which does both pal and ntsc) is pcb compatible you could also get the extra two pal modes by swapping the chip and using the other pin also.
     
  3. airs

    airs Spirited Member

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    I connected pin 55 (VAA) to pin 52 (CRTLB1) - success, 240p output. Motion is a lot clearer. S-video to XRGB Mini to 720p Plasma display (picture taken with iPhone):

    [​IMG]

    [​IMG]
     
    Last edited: Feb 8, 2015
  4. retrorgb

    retrorgb Spirited Member

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    What an awesome discovery! Unfortunately, my 3DO has the BT9101 chip, not the VP536A. It's RGB-modded, but since it outputs 480i, it doesn't look very good.

    I can't find a datasheet on the BT9101 anywhere, but do you think it's possible to force 240p on that chip as well?
     
  5. airs

    airs Spirited Member

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    Hey retrorgb. I was actually going to tweet this to you since I've used your site so much in the past year or so - thanks! I have an RGB modded (Otaku's kit) FZ-1 with the BT9101 as well and couldn't find a datasheet for the life of me. I couldn't stand the 480i output, especially knowing that internally everything is rendered at 240p! So, I bought a Goldstar last week and now here we are. I'd still like to get it working on my FZ-1 so I'm planning to do some poking around this week with it. Hopefully I don't fry anything :)
     
    Last edited: Feb 9, 2015
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  6. retrorgb

    retrorgb Spirited Member

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    Good luck and definitely keep us posted! I contacted a few other people that might be able to help and sent them a link to this forum...hopefully we can figure it out.

    BTW, do you (or anyone else) have a datasheet on the BT9101?
     
  7. airs

    airs Spirited Member

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    Nope, I've spent a good bit of time looking and haven't had any luck tracking one down.
     
  8. Bad_Ad84

    Bad_Ad84 Keyboard Error: Press F1 to Continue

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    Good mod.

    Id suggest using a resistor between the points, rather than directly connecting though.
     
    Last edited: Feb 9, 2015
  9. airs

    airs Spirited Member

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    What does adding a resistor accomplish? What resistance amount? 10 ohms? 100?
     
    Last edited: Feb 9, 2015
  10. crans

    crans Rising Member

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    Great find I'll have to test this once I get a free moment
     
  11. airs

    airs Spirited Member

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    Anyone know about the resistor?
     
  12. superg

    superg Site Supporter 2013,2014,2015. Tape Drive Donor.

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    Nice find airs!
     
  13. Bearking

    Bearking Konsolkongen

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    This is one of the best mods I've seen in a while :)

    I have no experience with the 3DO and I have no plans of getting a system. And I had no idea that it outputs 480i only (which is retarded). Being quite obsessed with picture quality on my systems, I go to great lenghts to play in the correct refresh-rate (60Hz), at least RGB and I try to avoid interlaced signals whenever possible.
    Knowing how troublesome it is to force other systems in progressive scan and 240p, it's just so cool that it can be done so easily on the 3DO :D ...I wonder why the engineers didn't add this feature when they made the system :/
     
  14. airs

    airs Spirited Member

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    Hi superg, thanks! Btw, my two gscartsw are still holding up perfectly :)

    According to patent documentation, there is also a way to control interpolation via software. I'm interested to see what effect, if any, this would have on output resolution. I'd like to code a hello world sample for 3DO and play with the calls, just need to find some time to do so.

     
    Last edited: Feb 12, 2015
  15. superg

    superg Site Supporter 2013,2014,2015. Tape Drive Donor.

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    Good to hear! I'm finishing 3rd and final version (EL1883, powered, VGA + SCART and 3.5 audio jack).
    As of 3DO, for me it would be more interesting what we can do with BT9xxx encoders. I know that it accepts RGB matrix and it can output S-Video in addition to composite. That encoder is used in both Panasonic 3DO's and Philips CDi.
     
  16. airs

    airs Spirited Member

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    Yeah, I wish I could get my hands on a BT9xxx datasheet..going to have to wing it instead though.

    I installed a switch to swap resolution output and found that it does work while the console is running, which is nice for comparison purposes! Here is 480i (first) compared to 240p (second), taken with my Fuji X-T1 and 18-55mm lens. S-video -> XRGB Mini -> 720p Panasonic plasma display. For 480i I used Natural/Video. For 240p I used Picture/Game.

    [​IMG]

    [​IMG]
     
    Last edited: Feb 13, 2015
  17. abdominalpillaging

    abdominalpillaging Active Member

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    I just tried this on my NTSC fz-10 with an rgb mod. Unfortunately I only get a grey screen after connecting pins 52 and 55. That's through both svideo and the rgb jack I installed. It is, however, a 240p gray screen. Don't know if there's anything else to try to get it working, but if it means going out and getting a goldstar model that will have to happen.
     
  18. airs

    airs Spirited Member

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    Are you certain you were connecting the correct pins? The orientation of my VP536A was different from what the datasheet pictured - I used the PCB markings as a guide:

    [​IMG]
     
  19. abdominalpillaging

    abdominalpillaging Active Member

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    Yup, definitely the correct pins. I decided to try with a switch, and it seems that the fz-10 won't boot in 240p mode. You can boot in 480i and switch to 240p right away though. So its working just fine now. And damn, it just looks so, so much better.

    Awesome mod, very glad you discovered this. Also very glad you sent the YouTube message to me!
     
  20. airs

    airs Spirited Member

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    Excellent, so happy its working for someone else! I actually stumbled across your channel tonight while looking for MK Trilogy videos. Started with the N64 MKT video and then saw the SSF2T 3DO capture and figured you'd like to know about the 240p mod.

    Your 60fps videos look great btw - I can't wait to do some captures of my own (X-Capture Mini is on the way from Solaris Japan). I'd love to see some footage of the 3DO in RGB 240p/480i if you get the time - my Goldstar isn't RGB modded yet :(
     
    Last edited: Feb 16, 2015

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