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Thread: Mr do's wild ride video problem

  1. #1
    kynrek Guest

    Default Mr do's wild ride video problem

    Does anyone know these vertical lines are normal? Why are the numbers for the scores so hard to read?
    here's a video
    http://www.youtube.com/watch?v=Row-Q...1&feature=plcp

    Here is a better picture to show the problem. bottoms of the the letter t gets cut off in the diagnostic screen.



    By the way, the diagnostic said cpu1 & 2 OK and all roms OK

    The game is in an old Joust cabinet (don't know if that helps with possible monitor compatability issues)
    Last edited by kynrek; 07-02-12 at 02:49.

  2. #2
    kynrek Guest

    Default

    I tried using a rgb->VGA converter and hooking up a different monitor but the lines are still there and are more prominent.



    I also took out the pcb. No signs of bad capacitors.

    I believe this is what it is supposed to look like

  3. #3
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    The VGA converters I have seen didn't produce that effect. I would try a different board and see if the same problem occurs, a VGA converter could be bad out of the box.
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  4. #4
    kynrek Guest

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    I know the VGA converter is ok because I get the vertical white lines when I hook the board up to the original arcade monitor too. I only hooked up the VGA converter because I thought the original arcade monitor was bad but i guess thats not the case. Now I guess it must be a PCB problem but the self test said all the CPUs and roms were ok. I took out the board and didn't see anything obvious like a bad cap. Could there be any faulty wiring that could cause this?

  5. #5
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    Not likely, video ram is more suspect in my book.
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  6. #6
    kynrek Guest

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    I'm trying to find somewhere that sells the ram ic's but I've had no luck

  7. #7
    kynrek Guest

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    Here is what I'm looking for:

    Five of these:
    MB8128-150 NMOS 16k bit static RAM access 150 nsec





    One of these:
    Mb8128-100 NMOS 16k bit static RAM access 100 nsec


  8. #8
    kynrek Guest

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    I reflowed all the ram connections for connectivity and they all tested ok. I powered up the board and still have the same problem. I removed and reseated all the ROM chips I Also cleaned the entire board and still no luck. I think the diagnostic mode tests 3 of the 5 ram chips (according to the manual) with 12 test tones at 3 different pitches all 12 tones for each pitch beeped.

    That makes me think it must be one of the 3 ram chips that are not specified as part if the RAM test. One has a lower access time 100ns instead of 150 so I would assume that chip is the video ram. Should I try replacing that one first? Any other tips?

  9. #9
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    have you thought it might be the rom chip with the actual game in? Ive had similar issues on a NES where the carts have got damaged and display dodgy and no it was never due to the 72 pin connector. Im no expert but it just seems similar to what ive experienced.

  10. #10
    kynrek Guest

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    I don't know but the diagnostic said all ROMs were ok.

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