Put the original RAM chips back. That may solve the glitches. The issue was the TTL IC below and you already solved it. The "new" ram might be the glitches cause.
Poe a ram original de volta. O problema era o CI TTL em baixo e vc ja resolveu. A nova ram pode estar causando os glitches.
In fact it wouldn't because each card dump is encrypted with per card keys. It will be useful after encryption is defeated so keep it safe for now. It's exactly because the encryption key is unique per card we don't know how to decrypt it and copying data from one card to another does not work.
I suggest you check the voltage the programmer supplies the chip on the 5v rail during programming. That is exactly the kind of 27C4096/27C400/27C4000 my programmer would not do (older type with larger die, more segments). I made an extra adapter that boosts 5v to 6.5v on the eprom socket, that...
I just said the programmer does not supply what the EPROM requires to program properly.
Eproms that work with 5v rail:
NEC / Hitachi / newer ST chips with high density such as 27C800, 27C160 or 27C320/322
Eproms that won't work:
Almost everything else.
Why these programmers don't bump the 5v...
The problem is simple: Cheap Chinese chip programmers don't raise the 5V supply line to 6.5v and a lot of EPROM brands do require this to program. For example older ST Micro EPROMs need 6.5V at the VCC rail during programming.
Keep in mind that this issue of raising 5V rail (VCC) to 6.5V is a...
The rhythm of the music is defined by the timer on the sound chip which is part of the neo geo board. That is controlled by the Z80 which is also part of the neo geo board. The multi cart only provides the program for the z80 to run. I suggest you try the cartridge on at least one different MVS...
As I said privately to Darksoft on discord, this must have to do with the long traces that come from the CIF custom IC and go through the board up to the CN2 on the opposite side of the board.
The simms are flashable, they will hold whatever you install from the right CD. The two different ones that are close to the cart slot who keep program data. What is written to these two simms are what differ from one cart type to other.
Some games were rental or sample and therefore do not offer freeplay mode. Example, all Brazil games were (supposedly or so Japan Capcom wished them to be) rental and lack freeplay option and do display their digital coin counters when you press action buttons while on atract mode.
That is the point of the mentioned audio fix. The cps2multi introduced glitches on the PCM data being send to the A board. That's why it needed a modification.
You asked what/where the sound was generated and I answered. It is generated on the A board with data from the ROMs.
it is on the A board, the problem with the multi is that one of the graphics buffers drains some current that causes the audio buffers to malfunction, the A board get feed glitched PCM data which is reproduced at the speakers. The fix solves that issue