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Thread: Neo Geo CD Top Loader RGB shaking vertically

  1. #1
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    Neo Geo CD Top Loader RGB shaking vertically

    So Iíve been enjoying my Front Loader CD which I got in yesterday, but Iíve noticed using RGB that the picture shakes vertically when the console has been off for a period of time. It will keep this up for 5 minutes or so, slow down, and eventually go away. The picture doesnít shake at all off the AV port using composite cables (OEM SNK) or using the composite video jack. My SCART cable has a sync stripper built in, and Iím wondering if that might be the issue. I noticed the CD just pulls composite video direct from the jack for the sync pin on the AV port. Another thought I had was the caps considering it goes away after being powered on.

    Any ideas guys? Thanks.


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  2. #2
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    Quote Originally Posted by Digmac View Post
    So I’ve been enjoying my Front Loader CD which I got in yesterday, but I’ve noticed using RGB that the picture shakes vertically when the console has been off for a period of time. It will keep this up for 5 minutes or so, slow down, and eventually go away. The picture doesn’t shake at all off the AV port using composite cables (OEM SNK) or using the composite video jack. My SCART cable has a sync stripper built in, and I’m wondering if that might be the issue. I noticed the CD just pulls composite video direct from the jack for the sync pin on the AV port. Another thought I had was the caps considering it goes away after being powered on.

    Any ideas guys? Thanks.
    I agree with your caps diagnosis. It could also be bad/cracked solder so I'd give those a looking at while you're under the hood. Obviously a recap is probably worth it since the NGCD is 20 some years old

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    Quote Originally Posted by DasiyAge View Post
    I agree with your caps diagnosis. It could also be bad/cracked solder so I'd give those a looking at while you're under the hood. Obviously a recap is probably worth it since the NGCD is 20 some years old
    The solder looks good to go, but what I find odd is how they left the ground unsoldered on every component on the top of the PCB. They're all soldered on the bottom, but nothing on the top. You can see the copper pads like they've never had solder. Very interesting, and I haven't seen that on any other SNK product.


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  4. #4
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    Is the picture kind of bouncing up and down by one layer of pixels? I've had the happen before with a NGCD. No clue why though.

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    Quote Originally Posted by wyo View Post
    Is the picture kind of bouncing up and down by one layer of pixels? I've had the happen before with a NGCD. No clue why though.
    Yeah, it looks to be only one, perhaps two rows of pixels when the picture shifts up and down. It's pretty random too. Sometimes it wont stop moving, and other times it's just a jolt in the picture here and there.

    edit: I take this back actually. Sometimes it's worse and it looks like it's shaking by six or seven rows of pixels. The whole thing is random, how often it shakes and how bad it is.
    Last edited by Digmac; 10-09-2020 at 04:34 AM.


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    The video issue really isn’t going away anymore. Even having left the console on for 30+ min, it still shakes. Here’s a video example of what it looks like.

    Edit: Just ordered a cap kit. We’ll see how that goes when it comes in.

    Last edited by Digmac; 10-16-2020 at 12:38 AM.


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  7. #7
    JammaNationX
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    Bad sync it looks like, try a sync cleaner.

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    Quote Originally Posted by Xian Xi View Post
    Bad sync it looks like, try a sync cleaner.
    My SCART cable has a sync stripper wired in line. Would that cause issues?


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    Update, tried a new SCART cable WITHOUT an in line sync stripper, still has the video issue. Fully recapped the video/audio/power board, still has the video issue.

    Any thoughts?


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  10. #10
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    Update. Cut the traces for composite as sync, jumped the sync in off the encoder and the issue is still there. I noticed if I use the SCART cable without the sync stripper, I get checkerboarding on every sprite. If I use the SCART cable without the sync stripper on my AES, I get the same jumping/shaking video as my Neo CD.

    I'm at a loss here. I don't know what else to try.

    edit: cable has a sync cleaner, I should say.
    Last edited by Digmac; 10-24-2020 at 08:49 AM.


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    Update: Sync from luma has the same issue as composite video as sync. Sync off the encoder was finicky and is displaying a very (unplayable) dark picture.

    Mobo has been recapped. AV/power board has been recapped. A sync cleaner doesn’t help. Doesn’t matter if it’s composite video as sync, sync on luma, or sync from the encoder, they all have issues.


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  12. #12
    JammaNationX
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    Trace it back to the bottom board to see if it passes through anything like a TTL chip that might be failing.

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    Quote Originally Posted by Xian Xi View Post
    Trace it back to the bottom board to see if it passes through anything like a TTL chip that might be failing.
    The pin for sync to CD-ANA-2 goes straight to the NEO-GRC, pin 68.


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  14. #14
    JammaNationX
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    If you have a scope DC the top board and see if the sync is funky from the source. If it’s clean then the problem is on the encoder board.

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    Quote Originally Posted by Xian Xi View Post
    If you have a scope DC the top board and see if the sync is funky from the source. If it’s clean then the problem is on the encoder board.
    I sadly don’t have a scope. The fact that TTL level sync from sync in jitters isn’t reassuring.


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  16. #16
    Haomaru's Blade Shiner
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    Had the same issue ( in an Philips CRT)
    Also using scart, shield self made, no sync stripper .

    What fixed it was the same solution I used for my mv1fz that is picky with some TVs

    1k pot on sync line
    Then I measured the right resistance, and just added an approximate resistor inside the scart, on sync pin

    Never had the issue again

    And yes recapping the full system was an good idea, that's the first thing I did as well

    Cheers
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

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