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Thread: mv1fs stuck watchdog,with click from speaker

  1. #1
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    icon18.gif mv1fs stuck watchdog,with click from speaker


    hello everybody
    about my motherboard like this:https://www.mvs-scans.com/index.php/MV1FS
    today i try to repair a slot mv1fs who have problem of stuck watchdog cpu 68k,with garbage screen with click click coming from speaker,so i look th cpu with oscilloscop ,i have clock but no data /address lines from cpu ,sp1 and rams.i change with new pieces work ram and backup ram,no change.new cpu 68k,new sm1,sp1,6116,74hc32,74hc04,74hc259 ,d4990 but always problem.The sp1 /OE look high and CE low.
    the rams have 27 pins high.please help
    thanks you and sorry for my poor english.
    Last edited by babeloued; 12-19-2020 at 03:36 PM.

  2. #2
    JammaNationX
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    Trace the SP1 /OE, it needs to be low for anything to work.

  3. #3
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    thanks xian xi
    i check the trace of sp1 on pin 20 ,the signal coming by neo-eo but still high,i change it but the same problem.
    i check some 4 ttl in the top of motherboard,like 74ls245,74ls32 all ok
    For checking ,can you give me the traces connections about all rams,sp1,cpu ,z80 and more about this motherboard mv1fs,please?
    Last edited by babeloued; 12-20-2020 at 04:37 AM.

  4. #4
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    icon18.gif

    after check all cpu to rams,sp1,neo c1,neo eo and neo fo,no b1 and neo lspc ,i change all ttl , 2x 5864 ,z80 ,6116 ,neo d0 ,neo f0 ,but still watchdog.
    some times it want to start a few seconds and no clicking ,a garbage screen coming with some symbol of alphabet but no moving,and re clicking again a long time but no data or addresses lines are active on sp1,cpu,work rams.
    is it possible the neo-b1 is bad and causing the click of death?
    please help,i spend time with this problem,and i coming mad

  5. #5
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    great
    today i try another neo-c1 ,and bingo ,my board boot now.
    but i have another problems now.
    first when the slot boot the first time,i have cross hatch half correct and half bad with corrupt caracter,i try diagnostic smkdan ,result( palette error )and some time when i swapped another 5864 i have video error with corrupt caracter write.but my 2 video ram are new(5814) and all 62256 are new.
    but now i m not happy because i have backup ram error and the 2 rams are new too.
    can you explain this problem or it is a mistake of diagnostic.
    now i buy 2 cxk5864 and i will see when i receive parts from china.
    thanks for help me ,and tell me how is not correct.
    Last edited by babeloued; 12-28-2020 at 10:12 AM.

  6. #6
    Edo Express Delivery Guy
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    Have you tried clearing the back up ram in the hardware test? Might need to do it a few times since you got new ram

  7. #7
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    hello
    yes i do it a longtime ago.
    this night,i loose message about backup ram error and now i have again video ram error with original bios and with smkdan diagnostic there is vram data (0000 with corrupt alphabet,and i confirm the 2 cxk5814 are new.
    IMG_20201228_220656-min.jpg
    Last edited by babeloued; 12-28-2020 at 04:20 PM.

  8. #8
    Morden's Lackey
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    The cxk5814 are the 2k fast vram chips. The address in the error is in the range for the 32k vram chips.

    https://github.com/jwestfall69/neoge...am-vs-32k-vram
    https://github.com/jwestfall69/neoge...ations/mv1f.md

    Prior to replacing them I would try placing downward pressure on the LSPC2-A2 chip and see if it has any effect. If it does you might just need to re-flow it.

  9. #9
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    thanks for your reply
    32k vram chips are replaced by new 62256 but in 70ns and the LSPC2-A2 reflow too a few days ago.
    i just reflow neo-b1 and the graphic is now correct ,but some time when i boot the slot with unibios 4.0 ,the cross hacth and the mire bars colors looks correct and when i play a game some corrupt graphic arrive and the sound play slowly.
    with the smkdan 0.19a00 ,the graphic are all ok but only the test crash with vram 32k loop.
    this is my last tests
    Last edited by babeloued; 12-29-2020 at 03:49 AM.

  10. #10
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    hi
    now i change the LSPC2-A2 and have some good news but not perfectly.
    when i have the original bios ,it say video ram error,
    when i have the unibios 4.0 ,i have cross hatch screen without the red color around the screen,and i can play game without some graphic.
    when i have the diagnostic smkdan 1.9a00 ,i have this pictures
    IMG_20210103_142532-min.jpg
    IMG_20210103_142823-min.jpg
    IMG_20210103_142713-min.jpg
    IMG_20210103_142751-min.jpg
    the 2 colors bars are icomplete,it look that
    IMG_20210103_142834-min.jpg
    IMG_20210103_142842-min.jpg

    i change another time the 32k video ram and 2k video ram
    all ttl are test good,i think a trace is cut ,but i don t have the connections traces with different ICs to test with multimeter
    i m waiting yours help
    thanks
    Last edited by babeloued; 01-05-2021 at 12:17 PM.

  11. #11
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    hello
    anybody want to help me????

  12. #12
    JammaNationX
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    So you still have these graphics problem after you swapped the video ram?

  13. #13
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    hi
    yes it is the same graphics problem when i swap the video ram
    so this afternoon i try to repair a mv1fz board and i swap the neo -c1 of mv1fs board ,and i have the same graphics problem on mv1fz so the problem is the neo-c1
    but why vram error?
    when i put unibios 4.0 some times it is look correct but the graphics when i play game is not correct,and some times cross hatch is bad,when i push B botton many times the graphic begin correct
    can you explain me,thanks xian xi
    Last edited by babeloued; 01-16-2021 at 01:32 PM.

  14. #14
    JammaNationX
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    A bad Neo-C1 would make all those things happen as it handles controller inputs, decodes signals for 68k and LSPC2 and can affect palette ram and video ram that way. Swap it out.

  15. #15
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    ok i will try another one if i have it.
    anybody can buy me a good neo-c1?
    thanks for your help
    Last edited by babeloued; 01-17-2021 at 12:52 AM.

  16. #16
    Edo Express Delivery Guy
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    Got a parts MV1FZ, international shipping might be a bitch but I'll sell it at cost of shipping and a beer

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