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Museum of the Game® & International Arcade Museum® Forums
Hoping to get some guidance with this Taito Bubble Bobble board set I'm working on. First Taito board set I've worked on. My favorite all time arcade game and I'm trying to get it added to my collection. Pictures below of the graphics issue. Heres some things to note:
-board boots up and will play blind. Test mode shows same unreadable display.
-No sounds whatsover (The active low "Sound" output from IC 39 pin 12 is always high) Have replaced IC39 but no change. GAL problem?
-have tried two different K4900 monitors with same result (Both using negative composite sync H and V tied together on negative input)
-Have verified the ROMS on both CPU and video board to be good.
-Had some bad 2018 RAMS on video board that I replaced with MB8416 (all check good on my inquisitor) I read something about possible timing issues so need to confirm these are OK in BB?
-work ram checks good on inquisitor
-2016 RAM1 checks good on inquisitor
I have done a lot of probing with my oscope and all of the bus lines and logic lines seem to be functioning normal. nothing jumps out I'm waiting on some GAL16V8's to try fresh GAL's. I'm hoping it is not the custom PS4 chip. All lines on that chip are outputting ok.
So what is clobbering the display and the sounds? I'm guessing they are both related to each other. I've been known to overlook some of the stupid simple things on other projects so that can't be ruled out either.
Thank you so much for any help that can be provided.