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  1. Replies
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    Right. Lifting the pin is ideal, and you *must...

    Right. Lifting the pin is ideal, and you *must not* ground it.
    The pin is driven by a strong buffer that would simply be destroyed by grounding the pin.
    Leaving an unused output like that floating...
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    ? You can see them going from VDP to the memory...

    ?
    You can see them going from VDP to the memory modules, but yeah, they're right around the analog video outputs.
    Genius engineering ><
  3. I have an MD similar to this. Mine will not play...

    I have an MD similar to this.
    Mine will not play Mega Drive games but work fine in Master System mode.
    The LED is fine on mine though.
    I worked out that the problem on mine is the 68000: It's...
  4. Yep, those are normal.

    Yep, those are normal.
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    Yeah, a video amplifier low pass filter will not...

    Yeah, a video amplifier low pass filter will not shift pixels visibly, but using delayed sync with direct RGB (or the other way around) will.

    If you want all options, the THS 7374 has 4 channels...
  6. Great development here! I wish I had more time...

    Great development here!
    I wish I had more time to spend on this. It'll be a great learning experience on opamps in practice.

    Thanks for the schematics and for linking the perfect sound generator...
  7. Could you clarify this a bit? Power rails means...

    Could you clarify this a bit? Power rails means the supply to me, so 5V and ground.
    I imagine you mean something with R72 and R73 though?
    There are several games that easily max out the working...
  8. Have you tried increasing the coupling capacitor...

    Have you tried increasing the coupling capacitor size? :)
  9. Hi, why do you say an increased DC offset is...

    Hi,
    why do you say an increased DC offset is undesirable?
    The coupling capacitors will remove it for us. Is the required offset too large, does something saturate?

    Using different opamps is a...
  10. Bit hard to measure sporadic oscillation, as the...

    Bit hard to measure sporadic oscillation, as the scope probe itself has a big effect on this.
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    You probably know this but Sony's PSX uses this...

    You probably know this but Sony's PSX uses this encoder and there's a service manual available for it (PU-18 board).
    On that machine, the encoder works very well. You don't find any jailbars or...
  12. That's a nice find! Could you find out what...

    That's a nice find!
    Could you find out what circuit this capacitor tunes?
    It's probably connected to the CXA1145 directly, or maybe via a resistor or inductor.
    From your description, it sounds...
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    You will hit your "bandwith limit" once the image...

    You will hit your "bandwith limit" once the image is being projected onto something ;)
    But regardless, the VDP doesn't even output pixels sharp enough to justify a CXA2075.
    The extra bandwith is...
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    The newer encoders have faster slopes in RGB,...

    The newer encoders have faster slopes in RGB, theoretically resulting in a sharper image. You won't see a difference in practice though, unless you have a perfect upscaler and use an LCD.
    Everything...
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    Update: The CXA2075 needs careful denoising and...

    Update:
    The CXA2075 needs careful denoising and ringing prevention. Then its Y-Trap filter will work very well and fix most of the rainbowing.
    Imgur Album with the results:...
  16. The signal you feed into the RGB encoder needs to...

    The signal you feed into the RGB encoder needs to be conditioned well. Amplitude, signal shape and absence of all noise and oscillation are important.
    I don't think any of us hobbyists can do a...
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    I've tried using a 4.43Mhz crystal before,...

    I've tried using a 4.43Mhz crystal before, creating a PAL60 output. The image had color but lots of dot crawl and general ugliness.
    It could've been a poor quality signal though, as I didn't have an...
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    This is a reasonable source for the problem....

    This is a reasonable source for the problem. Posted on the nesdev.com forums.


    In 320px mode, the Genesis VDP's dot clock is ~6.712 MHz, and an alternating dark and light pattern would oscillate...
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    Jailbars are a common issue on retro consoles and...

    Jailbars are a common issue on retro consoles and they're a relatively simple fix. You just need to employ some denoise methods like shielding and additional capacitors.
    The rainbow banding on...
  20. Did you think of reducing PCB size by...

    Did you think of reducing PCB size by re-purposing existing components on the mainboard?
    Also there's a lot of wasted space. Traces could be cut and new components be places there.
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    I believe I will find the problem by continued...

    I believe I will find the problem by continued elimination of factors.
    - The encoder itself is now out of the picture.
    - The 32X demonstrates that re-encoding the amplified Genesis RGB also fixes...
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    Genesis jailbars are high speed signals creeping...

    Genesis jailbars are high speed signals creeping into the RGB signal and analog 5V lines.
    This can be fixed by adding lots of capacity to the 5V line, also placing small capacitors close to the VDP...
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    Hoping to revive this thread with some additional...

    Hoping to revive this thread with some additional information.
    I'm trying to get a rainbow banding free composite picture as well. To that end I've now tried replacing the CXA1145 with a modern...
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    I would've guessed it would be 10V 100u as well,...

    I would've guessed it would be 10V 100u as well, lol.
    So is this a bucket converter with *huge* voltage spikes or what?
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    People have found a way to run software from a...

    People have found a way to run software from a Memory Card via the built in manager.
    There's also a known bit of code that unlocks the cd controller so that it runs CD-R.
    All it takes now is to...
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