Bust a Move/Puzzle Bobble: Pixel errors

[maki]

Hi all

Ich have an original MVS Bust a Move cart here that has "pixel" problems, the other og Bust a Move cart I have doesn't have that problem.

I hope you can see that on the video, a static image ain't good for capturing that.
You can see the problematic pixels on right side, next to the green star, above the two blue balls.

https://imgur.com/a/aV3R4HJ

I've reflown the NEO-273 and the LS74 in the CHA board, no change.
From what I think I understand, the problem will be on the CHA board, C-ROM?

It seems like the broken pixels will be next to normal pixel on the right, like a buggy shadow pixel?
A floating address or data lines maybe?

If you need other pictures/videos of the problem let me know

 

[maki]

quick update:
the problem is definitely on the CHA board

I've swapped the NEO-273, no change
swapped the LS139, no change
tested the LS74 with my TL866II Plus, tested fine

haven't swapped the NEO-ZMC, its responsible for the sound anyways, but I've reflown it anyways

I've reflown all the remaining ROMs/ICs/components, when I did that for the two ROMs marked as C6 and C5 (D96-03 and D96-02), that did make a difference, the graphic issue was nearly gone
after removing and "soldering through the vias just in case", the problem was back to the original state, not good

the only ROMs on this PCB relevant for Busting a Move are the two C-ROM C5 and C6, then the S1 and M1 ROM, that doesn't leave much possibilities

I suspect one of the two C-ROM ICs to be faulty, wouldn't the first time that heating up an IC changes the error slightly, at least temporary

Edit:
I've desoldered the D96-02 and replaced it with a 27C4100 which is 100% pin compatible with the original HN62444P, the problem is gone now
The old D96-02 did however readout the expected checksum, but it wouldn't really work in the real world.

 

[pierpa86]

C5 rom, the answer is always the most obvious one.
GG