If I use the normal BIOS it goes into watchdog and a yellowish-black moving streak up and down the screen (with game in) or blue but clicking (Without a game) @ BB
The board is definitely pressure sensitive @ GadgetUK
To fix this pressure sensitivity, I took my hot air de-soldering gun to the EO and LO last night as those 2 ICs were reacting to the slightest touch while powered on. (I know, super scary as I could have messed it up worse lol)
Mission accomplished with the pressure sensitivity for the most part, LO isn't impacted by pressure nor the E0 anymore.
Surprisingly the only thing impacted by pressure now is the BIOS chip. (Even after re-flowing all the solder on the socket)
The BIOS will work but only if its positioned a certain way.
Still getting the same error with the diag. BIOS so yay I didn't break anything further lol.
I am going to check the connections between EO and the 68k like GadgetUK is proposing, maybe the signal is dropping somewhere to the BIOS.
Noob alert:
I am looking through the schematics here
https://wiki.neogeodev.org/index.php?title=Schematics and looking for one that shows both the 68k and EO in the same pic but I am not seeing one? Am I missing something?
Sorry in advance, I am really trying to learn this stuf but I can catch on quick if nudged in the right direction lol. (I.e Super happy with how I fixed my WRAM issue by converting Hex to Binary to see which dataline was giving me issues)
Million dollar question here, when the Diag. BIOS calls out A13 to A15, how do I know which A13, A14 and A15 its referring to lol?
I look at these schematic pages: (I.e 68k 68k user RAM NEO-C1 PDF and System latch NEO-E0 Power supply) and I see differing A13's (I don't expect them to keep A13 the same throughout the board) - you know what I mean? lol
I guess I need to learn how to read these things, I got this far because Xian Xi's Partial connections (Based on AES 3-4).
Would you let me know if I am close in my thinking below? *attached image
View attachment 54183
You all rock! Thanks for your help