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Thread: AES 3-6 with video issue

  1. #1
    . cvenditti's Avatar
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    AES 3-6 with video issue

    I recently bought an AES 3-6 with video garbled. The board is clean and came with socketed bios and 2 470uf caps replaced near the din8 connector.
    It ran the NeoDiag without issue.

    When stating the Unibios splash screen image is flawless but when the Neo-Geo logo and game video are displayed the video is really distorted.

    I think it might be a sync issue.

    Did someone had the same issue, which part should I start replacing? - Thank you
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  2. #2
    Geese's Thug
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    Definitely looks like a sync issue. what output are you using? Composite, svideo, rgb? I believe there are some other threads that said adding a resistor and a 220uf cap to the sync line has helped. I cannot remember what the resistor value was. I'd message Jamma nation x on messenger and he should be able to sort you out quickly.

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    Thank you for the quick reply. I'm using RGBs. A/V cable, TV and power supply work fine with my other AES. Looking again at the A/V schematic the cxa1145p could also be the issue since it look like the sync is going through it. I will look more in detail to the others threads for the 220uf cap and resistor.

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    Angel's Love Slave
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    Does your SCART cable have a sync stripper? If you’re using RGB, I would do an RGB bypass and a direct C-Sync restore. Details on how to do it can be found on the jammanationx website.


    http://www.neo-archive.com

  5. #5
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    So my RGBs/SCART cable that works on my 3-4 will not work on a 3.6 (because of the composite being on the pin3 too) - correct?

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    Could be, I'd say it's worth a shot

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    I just did the RGB bypass. It it better the the images have the colors flickering and too dark I measured the voltage peak to peak of the sync it is not stable (between 380mv to 712mv).IMG_20200912_155418961[1].jpgIMG_20200912_155535780[1].jpg

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    Check the frequency coming off the crystal oscillators. If they aren't stable then I'd check to see if the power going into them is stable. That might help you narrow it down.

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    The crystal measure between 23.98-24.20Mhz. I also check on of my MVS (24Mhz not the AES 24.167829MHz) it also fluctuate at tiny bit like that. After the regulator I have a solid 5Volt.

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    Interesting. A DFO would likely fix this for you or an external sync cleaner.

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    Quote Originally Posted by DasiyAge View Post
    Interesting. A DFO would likely fix this for you or an external sync cleaner.
    I just tried, I had a DFO 5Volt in one off my MVS. Well it is the same. I can say with confidence that is not the crystal nor the a voltage issue. I'm running out off idea. what else could do that.

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    Try reaching out to Xian Xi or jammanationx on messenger. He might know what's going on but I'm at a loss. Last thing you could try is a potentiometer on the sync line and try adjusting it until the sync is regulated but the dfo should have fixed that. Are you grabbing sync before or after the CXA1145P? If you're getting it after check pin 10, the voltage should be a low of 0.8v and a high of 2.0v. Does the cable you're using or the AES circuitry attenuate the sync? Should be pulled down with a 75ohm resistor.

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    Quote Originally Posted by DasiyAge View Post
    Try reaching out to Xian Xi or jammanationx on messenger. He might know what's going on but I'm at a loss. Last thing you could try is a potentiometer on the sync line and try adjusting it until the sync is regulated but the dfo should have fixed that. Are you grabbing sync before or after the CXA1145P? If you're getting it after check pin 10, the voltage should be a low of 0.8v and a high of 2.0v. Does the cable you're using or the AES circuitry attenuate the sync? Should be pulled down with a 75ohm resistor.
    I try both pins. the potentiometer is a good idea, I will give it a shot - thank you for all the help

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    Quote Originally Posted by cvenditti View Post
    I try both pins. the potentiometer is a good idea, I will give it a shot - thank you for all the help
    I try the potentiometer it is the same. Here is some pictures of the issue. I'm wondering if that could be the LSPC2-A2 for the sync or one of the 74LS for the colors? I' will try to contact Xian Xi. Thanks
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  15. #15
    JammaNationX
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    It looks like whatever you are using to display RGB doesn't like composite video as sync. Use a sync cleaner if need be.

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    Quote Originally Posted by Xian Xi View Post
    It looks like whatever you are using to display RGB doesn't like composite video as sync. Use a sync cleaner if need be.
    But I did the RGB mod. I get the SYNC (attenuated) before the CXA1145P. Do I still need a sync cleaner (I have couple LM1881)?

  17. #17
    JammaNationX
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    So you attenuated a possible "dirty" signal. The waveform looks staticky asf, I'd put the sync cleaner in and then attenuate the output. Check the waveform after that to see if it makes it better.

  18. #18
    JammaNationX
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    Also make sure the output cap is changed out, I've seen some go bad.

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    Quote Originally Posted by Xian Xi View Post
    Also make sure the output cap is changed out, I've seen some go bad.
    I did change the caps.
    Is this will work to clean the Sync?
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  20. #20
    JammaNationX
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    I’ve never used a 75ohm pull down on the input before.

  21. #21
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    Unfortunately the LM1881 did not fix the issue.
    I follow the instruction on retro RGB (https://www.retrorgb.com/syncstripperchiponly.html).
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  22. #22
    JammaNationX
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    Who made the cable?

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    Quote Originally Posted by Xian Xi View Post
    Who made the cable?
    I have 3 SCART cables from different source which all are working fine with my MVSs and my other AES (3.4). All are producing the same image with the 3.6. I also try with my PVM (I made the cable which works fine with AES and MVS) I have a rolling image.

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    Should I try to take the the sync directly form the LSPC2-A2 (pin 150)?

  25. #25
    JammaNationX
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    If you tap it on pin 10 of the CXA, it’s the same.

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