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Thread: Pics: Sigma Raijin video board rework

  1. #1
    Watches My Little Pony
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    Pics: Sigma Raijin video board rework

    I bought RAZO's broken Sigma Raijin, hoping that the video board was repairable. It is, in the barest sense. A few traces were vaporized, the circuit board was cooked clean through in one place, and every IC was dead. Luckily, it's a pretty simple board, with all standard parts, and essentially all of them are labeled in silkscreen. With a knockoff Hakko and 1997's most affordable oscilloscope, I got to work.


    This is what the video board looked like to begin with:
    video_before.jpg

    I clipped off the obviously fried parts and took the pins out with solder wick.
    video_cleanup.jpg

    I desoldered all the ICs too. I replaced the ICs with sockets, and replaced any questionable passives too.
    video_repaired.jpg

    I don't have an LM1881N or a CXA1645 on hand, but I replaced the standard logic parts, and saw that the subcarrier oscillator (CXA1645 pin 6) and asynchronous autofire (connector pin 4) both worked.

    subcarrier.jpgautofire.jpg

    When I get the video parts in, I'll post pictures of it (hopefully) working.
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  2. #2
    Neo*Geomancer
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    Good luck, hope you get it working!

  3. #3
    Withered Penis!
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    Wow, this is an interesting breakdown Spam, thanks, and I hope you get positive results here.

    Quote Originally Posted by Walter Benjamin
    As for the collector, his collection is never complete; even if he is missing but a single object, all that he has collected nevertheless remains fragmentary...

  4. #4
    Guerilla Warrior
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    Nice work man hope you get it up and running again.
    "NG.com breaking balls & crushing dreams since '99".

  5. #5
    Another Striker
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    Holy crap! Was this thing struck by lightning? Those cooked resistors really left a mark. Great job on restoring it, though.

  6. #6
    Formerly Raz_Hoe.
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    Quote Originally Posted by Morden View Post
    Holy crap! Was this thing struck by lightning? Those cooked resistors really left a mark. Great job on restoring it, though.

    Yea, Something like that.


    @Spam

    Can't wait to see it up and Running. I got faith in you bro.

    By the way, the harness and av cable was shipped out on Wednesday, so you should be getting it soon.
    Last edited by RAZO; 11-12-2017 at 09:35 AM.

  7. #7
    B. Jenet's Firstmate

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    Your repair is looking great.
    Goodluck and a nice score if you get it repaired.

  8. #8
    ネオジオ
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    Great report, good luck and please keep us posted!!
    凄いゲームを連れて。。。売った。

  9. #9
    Super Spy Agent
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    Loving those photo progress and detailed write up - hoping to see this beast back in business

  10. #10
    Krauser's Shoe Shiner
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    Really nice work and great to see the breakdown of the process.

  11. #11
    Kula's Can
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    Looking good. It’s always nice to see things get fixed rather then thrown in the scrap bin.

  12. #12
    Kyo's Flame
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    Is the PCB only superficially scorched? I thought scorch marks on a PCB can be conductive.

  13. #13
    Another Striker
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    Quote Originally Posted by DanAdamKOF View Post
    Is the PCB only superficially scorched? I thought scorch marks on a PCB can be conductive.
    At high voltages, and with the soot from charring still covering the PCB ... maybe. This board, even though it still has a mark, has been cleaned, and even if it wasn't, the voltage is nowhere near enough to cause problems.

  14. #14
    Watches My Little Pony
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    I checked for shorts between the components I replaced, and everything looked reasonable. I checked the resistance of the board around the soot and it appears to be nonconductive (>2Mohm). Thanks for the heads-up.

    I've got the LM1881 incoming from Digi-Key and some CXA2075 (Sony's replacement for the CXA1645, and apparently pin-compatible) coming from China.

    The power supply appears to be fine - output seems stable, and the manufacturer's web site indicates that it's protected against 1.5kV faults between inputs/outputs (so, anything that was caused by an AC line short shouldn't kill it, right?).
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