Taito Bubble Bobble graphics issue

Snowman10

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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.
 

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Bubble Bobble is quite a hard game to repair as 'everything is a sprite' - there's no tilemap - the backgrounds are all built from sprite 'strips'.

Pages 7 & 8 of these schematics seem most relevant to your problem as it's where the sprite X & Y positions are computed (check all the LS283's and LS163's). Page 9 is about getting the graphics data from ROM which seems mostly ok in your pics, and page 10 is the line buffer and palette which again seems ok in your pictures.

 
Took a week off on this one and came back to it.

Managed to sort out the sounds not working on the board. That ended up being the signal coming out of pin 9 on IC26. This is the clock signal for the 74LS374 that controls access to to the sound CPU data bus from the main CPU data bus. Pretty critical chip. I noticed on the scope that it was high and I could see it trying to switch low but never drop below 4 volts. So the line was being held high. Ended up switching out IC26 (74LS155), IC24 (74LS374) and IC 10 (74LS74) just to make sure the issue was fixed. Fired it up and sound works perfectly. Interesting sound problem as most of the other sound issues relate to the amplifiers.

Still probing around for the graphics issue. I appreciated Tendril's guidance and am looking on pages 7 and 8 but no luck so far. Will follow up with a write up when I find it.
 
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