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Interference on arcade monitor and JPAC - very puzzling!

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    Interference on arcade monitor and JPAC - very puzzling!

    So might not be the place to post but seem to have stumped most of the arcade places...

    I recently picked up an Astro City cab with a Nanao MS9 monitor and matching chassis. This worked fine with an MVS one slot with the original owner, but using a MAME PC I put together I appeared to be having the same issue with JPACS and GroovyMAME as I had on my Dino King conversion.

    I've two GroovyMAME PCs - one smaller Linux build and one larger Optiplex, the latter I put together myself and runs great on my PVM. I also have a homemade Pi2Jamma thingy and experience the same issues with this. When using any of my setups on a JPAC with my Astro 'm getting minor interference on the monitor and slight screen wobble, along with a wobbly 'pulse' when I first boot into a game. The interference is like a slight 'fuzz' effect, which is more visible due to the large screen on the Astro. I've tried the two JPACs I own and the issue persists - and I can't imagine being unlucky enough to have two bad JPACs! Oddly it seems to clear up the longer you play. After about 40 minutes it vanishes and the picture is stable with no issue. Bearing in mind that the PC setups all seem fine going VGA to BNC or VGA to SCART to BNC, all issues point to the JPAC portion of the setup. I had the same issues using a JPAC on my Dino King monitor where it would distort the image - although admittedly is markedly less on the Astro monitor. I've tried a triple shielded VGA cable from the Radeon GPU on the PC and the JPAC and still no joy.

    I've not rewired the Astro and it's running the original PSU. The marquee bulb is not present and everything else is original. I have disconnected the lamp ballast in case that was an issue.

    I shipped the chassis off to Grant (Gunblade) who has worked on these for years and years and repairs about 8 of these chassis' a day he told me! He confirmed there was no issue with the chassis, but got him to recap all the same. He thought the issue was peculiar and also couldn't figure out why it did that on my setup but suggested it was highly likely the tube was not at fault.

    Zaki has kindly shipped me a board to test, and I suspect this will work fine as John confirmed it worked fine with a board and can't see this being a tube issue.

    Has anyone got a MAME/JPAC setup working without interference? Just to recap: I tried 3 different setups: 1 Pi to Jamma (homemade), 2 x PC setups with different PSUs and still get the same issue. The weirdest thing is the issue settles down after 40 minutes.

    Could it be the 12 and 5V lines on the JAMMA adapter end? Since the JPAC is powered by USB, would the lines from the JAMMA end interfere with this?

    Anyone have any issues or no issues when running a similar setup?

    Cheers
    3DS FC (updated 2015): 0447-8108-3129

    #2
    I would also get the PSU recapped. Even ones which work and look ok need a recap (happened with one of my Cute PSUs - looked mint, but made my monitor act up).

    I sent my PSU off to Grant for a recap and it fixed my monitor issue.

    Comment


      #3
      Yeah could be a dry solder joint I reckon.
      3DS FC (updated 2015): 0447-8108-3129

      Comment


        #4
        Originally posted by Escape-To-88 View Post
        So might not be the place to post but seem to have stumped most of the arcade places...

        I recently picked up an Astro City cab with a Nanao MS9 monitor and matching chassis. This worked fine with an MVS one slot with the original owner, but using a MAME PC I put together I appeared to be having the same issue with JPACS and GroovyMAME as I had on my Dino King conversion.

        I've two GroovyMAME PCs - one smaller Linux build and one larger Optiplex, the latter I put together myself and runs great on my PVM. I also have a homemade Pi2Jamma thingy and experience the same issues with this. When using any of my setups on a JPAC with my Astro 'm getting minor interference on the monitor and slight screen wobble, along with a wobbly 'pulse' when I first boot into a game. The interference is like a slight 'fuzz' effect, which is more visible due to the large screen on the Astro. I've tried the two JPACs I own and the issue persists - and I can't imagine being unlucky enough to have two bad JPACs! Oddly it seems to clear up the longer you play. After about 40 minutes it vanishes and the picture is stable with no issue. Bearing in mind that the PC setups all seem fine going VGA to BNC or VGA to SCART to BNC, all issues point to the JPAC portion of the setup. I had the same issues using a JPAC on my Dino King monitor where it would distort the image - although admittedly is markedly less on the Astro monitor. I've tried a triple shielded VGA cable from the Radeon GPU on the PC and the JPAC and still no joy.

        I've not rewired the Astro and it's running the original PSU. The marquee bulb is not present and everything else is original. I have disconnected the lamp ballast in case that was an issue.

        I shipped the chassis off to Grant (Gunblade) who has worked on these for years and years and repairs about 8 of these chassis' a day he told me! He confirmed there was no issue with the chassis, but got him to recap all the same. He thought the issue was peculiar and also couldn't figure out why it did that on my setup but suggested it was highly likely the tube was not at fault.

        Zaki has kindly shipped me a board to test, and I suspect this will work fine as John confirmed it worked fine with a board and can't see this being a tube issue.

        Has anyone got a MAME/JPAC setup working without interference? Just to recap: I tried 3 different setups: 1 Pi to Jamma (homemade), 2 x PC setups with different PSUs and still get the same issue. The weirdest thing is the issue settles down after 40 minutes.

        Could it be the 12 and 5V lines on the JAMMA adapter end? Since the JPAC is powered by USB, would the lines from the JAMMA end interfere with this?

        Anyone have any issues or no issues when running a similar setup?

        Cheers
        My 20L4 exhibits similar behaviour when connected to the RGB-pi with 60hz games. 50hz is rock solid as is pure 60hz outputs from a jpn Saturn and ps1. Has to be a sync issue.

        Comment


          #5
          Yeah,all fixed now mate. Got Grant to recap the MS9 chassis and got a fab picture
          3DS FC (updated 2015): 0447-8108-3129

          Comment

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