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Thread: Help with a Video Ram Error on Mvs MV-1FZS

  1. #1
    Timid Neo Newbie

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    Help with a Video Ram Error on Mvs MV-1FZS

    Hello!
    I hope that someone in this forum could help me With a Video Ram Error on a mvs mv1fzs board.
    I replaced the bios With de diag bios, fixed a broken trace but now I have another video ram error.
    The diag bios identified the error as:

    VRAM DATA (0000)

    Adress: 000000
    Actual: 4000
    Expected: 0000

    I have checked again all traces and seems to be ok, could it be that one or both surface mounted slow vram chips are bad? Or a broken trace that I am unable to find?
    Do anyone have the ram5 and ram6 (slow vrams) pinouts to check it again in a better way?

    Thank you in advance.

  2. #2
    Paris-Dakar Rally Driver
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    pnauts's Avatar
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    if it's CXA43256
    adresses are:
    10
    9
    8
    7
    6
    5
    4
    3
    25
    24
    21
    23
    2
    26
    1

    datas
    11
    12
    13
    15
    16
    17
    18
    19

    all shall goes to a LSPC

  3. #3
    Timid Neo Newbie

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    Thank you pnauts, but I do not understand the pinouts you posted.
    I Know that all the legs of the ram5 and ram6 goes to some lspc2 legs, but do you Know the exact pinout leg by leg?
    Example:

    RAM5 LEG: 1 LSPC2 LEG: 5

    1-5

    ETC..

    VRAM chips in this board are a couple of lh52b256n-70 chips.
    Last edited by SELUXL; 11-25-2017 at 03:35 PM.

  4. #4
    Paris-Dakar Rally Driver
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    check VRAM pinout of this link

  5. #5
    Timid Neo Newbie

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    I have replaced the four Vrams, both slow a fast, checked all the traces and seems to be ok
    But The error persists.
    Time to think about a bad LSPC2? I do not Know what to do now..

  6. #6
    Astra Superstar
    dragonpt's Avatar
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    Had all sorts of this errors in one.

    After replaced all the rams, same thing...

    So ye, what really fixed it, was the ic
    Hyper Neo Geo 64 / Neo Geo CD - Top Loader / Neo Geo Poket Color/ Neo MVS - MV1FZ / 1B / 4F

  7. #7
    Enemy Chaser
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    Quote Originally Posted by SELUXL View Post
    Hello!
    I hope that someone in this forum could help me With a Video Ram Error on a mvs mv1fzs board.
    I replaced the bios With de diag bios, fixed a broken trace but now I have another video ram error.
    The diag bios identified the error as:

    VRAM DATA (0000)

    Adress: 000000
    Actual: 4000
    Expected: 0000

    I have checked again all traces and seems to be ok, could it be that one or both surface mounted slow vram chips are bad? Or a broken trace that I am unable to find?
    Do anyone have the ram5 and ram6 (slow vrams) pinouts to check it again in a better way?

    Thank you in advance.
    Take a look at the AES schematics (because they are clearer), and check your CS, OE, WE pins. Connected to the LSPC2 as pnauts mentioned. Could just be bad RAM.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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