Sega Master System II PAL to NTSC mod issues

Discussion in 'Modding and Hacking - Consoles and Electronics' started by Yoshiknuckles, Nov 5, 2016.

  1. Yoshiknuckles

    Yoshiknuckles Member

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    Hello,

    Recently I've modded a Sega Master System 2, converting it from PAL to NTSC.

    The motherboard is a IC BD M4Jr. PAL 2M.

    I've managed to convert it to 60 hz and NTSC, and I've managed to get color video, but the colors are a bit off for some reason.

    What I've done so far:

    -Lift pin 57 of the ASIC and tie it to ground.
    -Broke pin 7 off the original video encoder, so I lifted it off, cut the trace to pin 7, put a new MB3514 in the console which I stole out of a Genesis 2. I've tied it to +5V.
    -Replaced the PAL osc. crystal with an NTSC one.
    -Installed my composite and s-video amp board I use for CXA1145/MB3514 consoles. It's the 2SC945 circuit you can find on Console5

    At that point I had black and white video and no color.

    So,
    -I removed c26 and put a 100 ohm resistor in the positive hole, running a wire to pin 6 of the z80.

    I currently have color, but the red and green are a bit off. Any other suggestions for other things I can try? Maybe something with the external Y and C filters? I'm able to tune the composite to look acceptable color-wise, but the s-video just seems to have more green than it should.

    I'll include some pictures of my work.[​IMG] [​IMG]
     
  2. Yoshiknuckles

    Yoshiknuckles Member

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    Update: The culprit is likely the clock signal I was feeding into it.

    The MB3514 is expecting an AC coupled waveform between .3-.7Vp-p. I was feeding in 4.72V based on bad information I found online and in youtube videos. -.- That's what I get for listening to the internet without doing my own engineering research!

    Possible solution: Replacing c26, lift the leg of R10 closer to the cart slot, and feed the clock from the z80 into there. Then it can go through the voltage divider and decoupling capacitor, hopefully restoring proper color!
     
sonicdude10
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