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Archived from groups: rec.games.video.arcade.collecting (More info?)
First things first - this is a Nichibutsu Moon Base 3-layer boardset.
The problem *definitely* lies with the ROM board. a Taito ROM board
works fine if swapped out with this dodgy Moon Base ROM board.
Problem as follows - in cocktail mode for player one the the
grraphics, letters and numbers are flipped vertically so appear upside
down. When switching to player 2 the screen flips correctly and text,
graphics and numbers are the correct way around.
I have spent hours searching through the relevant parts of the video
invert circuitry on the ROM board - checked out all relevant signals
(even compared against a working Taito ROM board and cannot see any
obvious differences on the 'scope). Replaced the LS83's at locations
3D and 3E( locations 26 and 27 on a Taito S.I. ROM board) and the LS86
responsible for the video inversion. Have checked for shorts on both
inputs and outputs, broken tracks, weak signals - tried pulling up
certain signals, etc, etc, etc but all to no avail.
I'm hopelessly stumped.
Can anyone give me any ideas please on anything else that I might try?
Thanks
First things first - this is a Nichibutsu Moon Base 3-layer boardset.
The problem *definitely* lies with the ROM board. a Taito ROM board
works fine if swapped out with this dodgy Moon Base ROM board.
Problem as follows - in cocktail mode for player one the the
grraphics, letters and numbers are flipped vertically so appear upside
down. When switching to player 2 the screen flips correctly and text,
graphics and numbers are the correct way around.
I have spent hours searching through the relevant parts of the video
invert circuitry on the ROM board - checked out all relevant signals
(even compared against a working Taito ROM board and cannot see any
obvious differences on the 'scope). Replaced the LS83's at locations
3D and 3E( locations 26 and 27 on a Taito S.I. ROM board) and the LS86
responsible for the video inversion. Have checked for shorts on both
inputs and outputs, broken tracks, weak signals - tried pulling up
certain signals, etc, etc, etc but all to no avail.
I'm hopelessly stumped.
Can anyone give me any ideas please on anything else that I might try?
Thanks