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Thread: MV1FS Video Ram error.

  1. #1
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    MV1FS Video Ram error.

    Hello so Im finally going back to another busted board i have on my bench here and im getting a video ram error. Using a UniBios I get no sounds and missing video/sprites. Traces from the 4 rams around the LSPC2 look and test ok with continuity to the LSPC2

    Ill deal with the sound issues later.

    I was really just trying to remember which chips on these boards are the video rams. As you can see I have a photo of the rams around the LSPC2







    The Video Ram Error does not change its read or writes across power cycles and the address changed once on the last bit from 0 to a 3, but its not reproducible

    The astute among you may have noticed the two SMD rams on the left side were replaced with samsung rams of equivalency. Im just worried that i goofed and those are actually color rams and not video ram LOL

    Thanks Guys
    Last edited by Geekman1222; 09-29-2017 at 10:43 PM.

  2. #2
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    That error is associated with the two 24 pin dips (8914) in front of the sound amp. remove both and replace with sockets. I thought is 8000... check the traces around the dips.
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    Last edited by BIG BEAR; 09-30-2017 at 10:28 AM.
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    With the error right at the 0000 boundry and an output of FFFF it could be a missing enable signal.
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    Ok hate to bring this back up here guys. But I am still at a loss

    BigBear: I finally replaced and socketed the two 24pin dip rams but that only yeilded the exact same results.

    bustedstr: Would I just use a logic probe or analyzer to check and see if the enable signal is making it to the rams? (I realize I could just google how to do this, is there any special notes on checking for the enable signal as I have never done it)

    Does anyone have any other suggestions.

    Thanks again,
    Geekman
    Last edited by Geekman1222; 01-07-2018 at 10:29 PM.

  5. #5
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    The three SRAM enable lines should give you some sort of reading with a logic probe. Nothing at all means you need to ensure the traces aren't broken. A missing enable line can cause very strange problems with SRAM.

    Don't quite remember, but usually /CE is just tied to 5V with /WE and /OE being controlled by some other chip.

  6. #6
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    Quote Originally Posted by HeavyMachineGun View Post
    The three SRAM enable lines should give you some sort of reading with a logic probe. Nothing at all means you need to ensure the traces aren't broken. A missing enable line can cause very strange problems with SRAM.

    Don't quite remember, but usually /CE is just tied to 5V with /WE and /OE being controlled by some other chip.
    Thanks I'll look into doing this next.

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