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Taito L-Shaped PCB Repair Log (Sound PCB) Graphics Glitch


Share any logs or helpful information you may have to repairs of arcade PCBs, Monitors etc

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    Taito L-Shaped PCB Repair Log (Sound PCB) Graphics Glitch

    I had a faulty sound PCB which after socketing and replacing the LM3900's and the 7417's, I got all the sounds working but the sound PCB also had a graphics glitch.

    There were lines through the invaders, their shape was wrong and they would charge straight to the bottom of the screen after a couple of changes of direction and the game would reset.

    After probing the outputs of the 74151s I found IC [3] had it's output stuck low on pin 5.

    After changing it the was some improvement, the invaders were no longer blocky/wrong shape.

    Looking at the inputs of this bank of chips I found DS8 was stuck low, the input was coming from the 74175 at IC [12], pin 2.

    After replacing it the graphics glitch is now gone and the game plays normally.

    Last edited by Kaizen; 23 May 2019, 11:09 PM.
    Namco Starblade - Taito Cocktail 14" x 3, 20" x 2 - NZ SI PtII Upright - Chase HQ DX, Taito Top Speed - Taito Grand Champion - Taito Safari - LAI SI Head to Head Cocktail - SI Cocktail Clone x 2, Pong Clone x 3
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