Snes jr. with a cxa2075

Discussion in 'Finished Projects' started by Drakon, Jan 27, 2012.

  1. Drakon

    Drakon Active Member

    Since I was so impressed wtih the cxa2075 in my sega genesis making the picture quality much sharper than the cxa1645 I decided to try wiring the 2075 into my snes jr. Sure enough....the s-video picture quality is an improvement over the encoder built into the snes jr. So I tapped the rgb, sync, and colour subcarrier inputs of the encoder built into the snes. Don't worry the original encoder is still in the snes jr. and it still works great. I have s-video wired into the s-video output from my cxa2075 circuit:

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    Here's a screenshot

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    The screenshot looks a little messy but believe me the picture is definitely sharper than it was before. My capture card just picks up strange things that don't show up at all on my crt tv.
     
  2. ShockSlayer

    ShockSlayer Probably SS

  3. Drakon

    Drakon Active Member

    Thanks! It means a lot to get such nice comments from such a great modder like yourself.

    Screenshots comparing the s-video from an un-modded snes model 1 vs. the s-video from my snes jr. with a cxa2075 installed.

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  4. ShockSlayer

    ShockSlayer Probably SS

    Definitely looks crisper to me.
     
  5. Drakon

    Drakon Active Member

    The video encoder that's built into the snes jr. is also crisper looking than the model 1, it's about the same as a cxa1645. But the cxa2075 is definitely crisper than the cxa1645.
     
  6. Seren

    Seren Formerly known as thelukestir

    win, want to get a couple of these for myself 8)
     
  7. Drakon

    Drakon Active Member

    PM me for a commission. Or if you're good at modding yourself it isn't too difficult really. All you need to do is pick up a cxa2075 chip. Then you need to buy a sop to dip adapter for it. Then solder it into the adapter and solder the adapter into a precision socket or a breadboard. Then solder up the ntsc internal trap application circuit from the cxa2075 datasheet. I used this pinout sheet to find out where to tap r, g, b, sync, and colour subcarrier from the encoder that's built into the snes jr.

    [​IMG]

    Then you just wire everything up and assuming you wired and built things right you're good to go. Another note...using a 75 ohm resistors on the luma output was a little dark so I used a little less resistance than that. Also the snes jr has an issue with the chroma line I use a 470 ohm resistor on the chroma line before passing it through the 220 uf cap otherwise you get diagonal bars on chroma. Don't worry using 470 ohms doesn't weaken the chroma line.
     
  8. XCVG

    XCVG ModRetro Legend

    Where did you find the CXA2075? I can't even find a datasheet :confused:
     
  9. Drakon

    Drakon Active Member

  10. Hydrobradman

    Hydrobradman Member

    Wow, it looks a lot sharper and the contrast is vastly improved. It almost seems a bit too sharp?
     
  11. Drakon

    Drakon Active Member

    Looks perfect on my tv. One thing I noticed with most encoders is that you get this white border around graphics when there's contrasting colours. I've noticed that the cxa2075 has the white border greatly reduced. And the sharpness is nothing but perfection.

    In fact I'm so impressed with the cxa2075s image quality that I ordered a bunch more and I'm installing these encoders into all of my favourite consoles (and my supergun if all my pcbs work well with it).
     
  12. nterror

    nterror Well-Known Member

    This is beautiful.

    You are beautiful.

    I love seeing mods like this that aren't all about portables.
     
  13. Drakon

    Drakon Active Member

    Thankyou that's the nicest compliment I've had in a long time! I guess this's why I proudly display:

    "The non portablizer! Specializing in.....NES." in my signature :awesome:

    Engineering audio and video circuits isn't really a lot of fun and there's a reason why so very few modders out there do it. But the payoff is completely worth it in my opinion. Heck I think barely anyone has even built tiidos insanely awesome crystal clear audio mod (32 resistors + 4 transistors + a bunch of other crap = not so fun when hand soldering). I really need to find someone who can etch me some proper crystal clear audio mod pcbs and then I can build them and distribute them to the masses (I can install them too if people want).

    Luckily this snes circuit is simple enough to do by hand.

    And don't completely write off portables most of the portables I see on this forum aren't just a pcb wired into a screen and controller (cough cough mesojdm cough). A lot of the portables on this forum have sd card addons and cool things that would even be an improvement in the home console.
     

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