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Thread: mvs 4 slot mv-4F is acting really weird, running everything slow.

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    mvs 4 slot mv-4F is acting really weird, running everything slow.

    I've been searching around and can't seem to find any solution to my neo boards. For some reason every game I plug into my 4 slot runs really slow. I'm not talking about slowdown during gameplay. I mean it's almost like the CPU is underclocked. Example: Samuri showdown shows intro, the audio is already at the end of the intro and the video is still catching up. in League bowling, the Video is slow, audio plays at normal speed and finishes the intro. video is still trying to catch up. I have no idea where to start looking. Anyone seen something like this before?

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    Kuroko's Training Dummy
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    How does the oscillator crystal look? Try clearing the back up ram as well.
    Last edited by DasiyAge; 05-13-2019 at 11:12 PM.

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    So I replaced the crystal already originally. I replaced it a second time just for good measure the backup ram has been cleared I have a unibios and it hides a calendar error but ive already replaced the calendar chip as well and that did nothing. After all this stuff was replaced the neo Geo was working fine this just started happening recently. it looks like I get screen tearing and then eventually it just started running slow
    Last edited by marcux; 05-14-2019 at 06:43 AM.

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    Kuroko's Training Dummy
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    Have you checked the 68K? Grab a datasheet and test all the point to see if power and continuity are all in the proper places

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    Krauser's Shoe Shiner
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    You will also want to check on the NEO-D0 right next to the crystal. Part of its responsibility is to be the clock divider for the 24Mhz crystal.

    https://wiki.neogeodev.org/index.php?title=NEO-D0

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    Ok, So. Now that i think of it. I replaced the 32mhz crystal near the rtc battery. You are all talking about the 24mhz crystal near NEO-D0. I hadnt replaced that. It seems likly that could be the problem. Im going to order up that crystal before messing with neo d0. Is there anything Specific about the component, or can i just order any 24mhz crystal like this?

    https://www.ebay.com/itm/HQ-24Mhz-Cr...US%213&LH_GD=3
    Last edited by marcux; 05-15-2019 at 12:37 PM.

  7. #7
    Krauser's Shoe Shiner
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    Any should do far as I know

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    I replaced the 24 MHz crystal oscillator, with no change.. It's still running super slow.. odd.

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    Robert Garcia's Butler
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    Assuming that's the later 4 slot with a D0 - as ack suggested - D0! That's where the clocks come from - sounds like something internally is not clocking as it should in relation to one of more of the clock signals. Kinda divided by 2 or something as a result.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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    yeah, i'll give it a shot and take it from my donor board tonight

  11. #11
    Robert Garcia's Butler
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    Quote Originally Posted by marcux View Post
    yeah, i'll give it a shot and take it from my donor board tonight
    Let us know how you get on! One final thing I've just thought of - I had a slow down issue with an MV1FZ at one point years ago. It was like in slow-mo, but music sounded normal etc. Strangely I found that putting a finger near (not touching) a certain area on the PCB that the game started running at normal speed. A few people suggested it could have been a missing ground. I never understood what caused it for me, but I fixed it by reflowing the LSPC and B1 (strangely enough...). To this day I don't know how, but it must have had a bad connection on either the LSPC or B1. I've used that board for the last 6 years or so without issue since.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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