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Thread: Pinball Action - Tehkan: Graphics and sound problems! Help!

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    . ftadeufs's Avatar
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    Pinball Action - Tehkan: Graphics and sound problems! Help!

    Hello guys!

    I have a board i got from a friend that I would like to repair to good working condition again. Iīm trying to learn as much as I can about repairing boards and this is a good oportunity to practice more, and learn more, I hope...

    Itīs a Pinball Action from tehkan but itīs a bootleg. As far as Iīve seen by pictures over the internet is a 1:1 clone of the original board, but built cheaper.

    I havenīt found any schematics and AFAIK they dont exist. Does anyone have any experience with theese boards or knows any documentation or repair logs that might help? What kind of stuff is in which ROM? They are all masked roms or OTP PROMS, and I canīt dump them with my TL866II plus.

    The game runs, but the graphics are very weird. At first it was just alternate vertical lines (horizontal if the monitor is rotated 90š and the game is rotated), but now some graphics are gone. I have some spare RAM ICīs but I dont wat to start changing things like crazy. I want to learn how to do proper repair on arcade boards, regarding graphical issues with the sprites, etc. Where is the best place to start checking signals?

    I have checked with the logic probe some data lines and address lines on both Z80īs and RAM ICs, and iīm a bit confused. Some of the chip enable lines are Low active and working fine, but some others are pulsing. I also have observed different behaviour of data lines according to different stages of the game.

    I would appretiate some guidance over fixing this board if possible, please!
    Last edited by ftadeufs; 10-03-2019 at 03:19 PM.

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