Tech: Ms. Pac-man garbled display

Archived from groups: rec.games.video.arcade.collecting (More info?)

Hi all,

I recently picked up a Ms. Pac-Man cabaret and need some help with a
problem. The game's display is corrupted, as if the video display logic was
wonked. You can sort-of see what's going on, enough to know that the game
plays more or less OK (although Ms. Pac seems to move really fast), and
sound works fine.

Here are some pics of what the display looks like:

http://www.zerodaysound.com/mspac1.JPG
http://www.zerodaysound.com/mspac2.JPG

I've looked at various sites that cover various technical issues with Ms.
Pac but didn't come across anything that seemed to match this problem. I
haven't yet got a logic probe but it's looking like I'll need one :). Any
help is appreciated!

Thanks,
-Rob
7 answers Last reply
More about tech garbled display
  1. Archived from groups: rec.games.video.arcade.collecting (More info?)

    Tito <n0one@nowhere.com> wrote:
    : Hi all,
    :
    : I recently picked up a Ms. Pac-Man cabaret and need some help with a
    : problem. The game's display is corrupted, as if the video display logic was
    : wonked. You can sort-of see what's going on, enough to know that the game
    : plays more or less OK (although Ms. Pac seems to move really fast), and
    : sound works fine.
    :
    : Here are some pics of what the display looks like:
    :
    : http://www.zerodaysound.com/mspac1.JPG
    : http://www.zerodaysound.com/mspac2.JPG
    :
    : I've looked at various sites that cover various technical issues with Ms.
    : Pac but didn't come across anything that seemed to match this problem. I
    : haven't yet got a logic probe but it's looking like I'll need one :). Any
    : help is appreciated!

    Adjust the HSync on your monitor.

    The board's working fine.

    --
    Mark Spaeth mspaeth@mtl.mit.edu
    50 Vassar St., #38.265 mspaeth@mit.edu
    Cambridge, MA 02139
    (617) 452-2354 http://rgvac.978.org/~mspaeth
  2. Archived from groups: rec.games.video.arcade.collecting (More info?)

    Thanks for the reply Mark! The monitor is a WG-K4700 and I can't seem to see
    any H-sync adjustment (H-hold doesn't have an effect), but I'll keep poking
    around. I should note that the lines making up the picture are actually
    still (as in, they don't fuzz like snow), and Ms. Pac seems to move awfully
    fast - that's what leads me to think it's game PCB-based.

    Thanks again,
    -Rob

    "Mark C. Spaeth" <mspaeth@plancherel.mit.edu> wrote in message
    news:426b26f8$0$557$b45e6eb0@senator-bedfellow.mit.edu...
    > Tito <n0one@nowhere.com> wrote:
    > : Hi all,
    > :
    > : I recently picked up a Ms. Pac-Man cabaret and need some help with a
    > : problem. The game's display is corrupted, as if the video display logic
    > was
    > : wonked. You can sort-of see what's going on, enough to know that the
    > game
    > : plays more or less OK (although Ms. Pac seems to move really fast), and
    > : sound works fine.
    > :
    > : Here are some pics of what the display looks like:
    > :
    > : http://www.zerodaysound.com/mspac1.JPG
    > : http://www.zerodaysound.com/mspac2.JPG
    > :
    > : I've looked at various sites that cover various technical issues with
    > Ms.
    > : Pac but didn't come across anything that seemed to match this problem. I
    > : haven't yet got a logic probe but it's looking like I'll need one :).
    > Any
    > : help is appreciated!
    >
    > Adjust the HSync on your monitor.
    >
    > The board's working fine.
    >
    > --
    > Mark Spaeth mspaeth@mtl.mit.edu
    > 50 Vassar St., #38.265 mspaeth@mit.edu
    > Cambridge, MA 02139
    > (617) 452-2354 http://rgvac.978.org/~mspaeth
    >
  3. Archived from groups: rec.games.video.arcade.collecting (More info?)

    If your Z80 Processor (at 6B) isn't working properly, you'll get a
    screen filled with colour garbage like that. It could also be your
    9332-B Prom at 6H, your 74LS139 at 7M or your 74LS161 Motion Location
    ROM at 9C.

    I'd first try a different Z80, and see if this corrects the problem.

    Some other things to check:

    Make sure your piggyback boards at 5S and 6D are securely seated.

    Measure +5VDC across capacitors C2 or C3 (they should not be only
    2-3VDC - If so, check the Zener Diode D9 - if its bad sometimes it
    shunts 5VDC to ground).

    Good luck!
    Blaine.

    - - -

    >Hi all,
    >
    >I recently picked up a Ms. Pac-Man cabaret and need some help with a
    >problem. The game's display is corrupted, as if the video display logic was
    >wonked. You can sort-of see what's going on, enough to know that the game
    >plays more or less OK (although Ms. Pac seems to move really fast), and
    >sound works fine.
    >
    >Here are some pics of what the display looks like:
    >
    >http://www.zerodaysound.com/mspac1.JPG
    >http://www.zerodaysound.com/mspac2.JPG
    >
    >I've looked at various sites that cover various technical issues with Ms.
    >Pac but didn't come across anything that seemed to match this problem. I
    >haven't yet got a logic probe but it's looking like I'll need one :). Any
    >help is appreciated!
    >
    >Thanks,
    >-Rob
    >
    >
  4. Archived from groups: rec.games.video.arcade.collecting (More info?)

    Tito <n0one@nowhere.com> wrote:
    : Thanks for the reply Mark! The monitor is a WG-K4700 and I can't seem to see
    : any H-sync adjustment (H-hold doesn't have an effect), but I'll keep poking
    : around. I should note that the lines making up the picture are actually
    : still (as in, they don't fuzz like snow), and Ms. Pac seems to move awfully
    : fast - that's what leads me to think it's game PCB-based.

    Capkit.

    --
    Mark Spaeth mspaeth@mtl.mit.edu
    50 Vassar St., #38.265 mspaeth@mit.edu
    Cambridge, MA 02139
    (617) 452-2354 http://rgvac.978.org/~mspaeth
  5. Archived from groups: rec.games.video.arcade.collecting (More info?)

    B. White <bish500@cogeco.ca> wrote:
    : If your Z80 Processor (at 6B) isn't working properly, you'll get a
    : screen filled with colour garbage like that. It could also be your
    : 9332-B Prom at 6H, your 74LS139 at 7M or your 74LS161 Motion Location
    : ROM at 9C.

    Try again when you have some semblance of a clue as to what you're
    talking about. That CLEARLY isn't random characters on screen; it's
    the attract mode, but the monitor isn't synching. You can see the
    bally/midway logo torn up across the screen

    --
    Mark Spaeth mspaeth@mtl.mit.edu
    50 Vassar St., #38.265 mspaeth@mit.edu
    Cambridge, MA 02139
    (617) 452-2354 http://rgvac.978.org/~mspaeth
  6. Archived from groups: rec.games.video.arcade.collecting (More info?)

    Mark:

    Speaking of being CLEAR...you CLEARLY thought I was speaking to you.
    I wasn't.

    I hope this CLEARS things up for you.

    Blaine.

    - - -

    >B. White <bish500@cogeco.ca> wrote:
    >: If your Z80 Processor (at 6B) isn't working properly, you'll get a
    >: screen filled with colour garbage like that. It could also be your
    >: 9332-B Prom at 6H, your 74LS139 at 7M or your 74LS161 Motion Location
    >: ROM at 9C.
    >
    >Try again when you have some semblance of a clue as to what you're
    >talking about. That CLEARLY isn't random characters on screen; it's
    >the attract mode, but the monitor isn't synching. You can see the
    >bally/midway logo torn up across the screen
    >
  7. Archived from groups: rec.games.video.arcade.collecting (More info?)

    check the sync and the montior ground. that could cause it not to have
    the correct hold.
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