SEGACD MultiBIOS (FABombjoy's method) sound issue

[omnedon]

I've just done the MultiBIOS mod to a spare SEGACD1 here. I'm using a burned eeprom, byteswapped as per Luke's suggestion, with 4 images on it, 2 of the NA SEGACD BIOS, 1 Japanese MEGACD BIOS, and 1 European MEGA CD BIOS. All files pulled from an emulator on my computer.


I've got it socket installed no problem. I can get it to boot in all three regions, using a genesis modded for 50/60Hz, and JP/USA. Except only USA CD has audio. Any audio. Weeerd. No audio in gameplay either. I get the correct MEGACD screens, but no audio, unless I'm in US CD mode.

I'm gonna take a break and look at this with fresh eyes tomorrow. This is the second one I did today. The first one was with the special BIOS eeprom that Arakon sells for $40USD plus. Same install method, and it worked perfectly, and it did not require a modded Genesis. It also had Columns on the eeprom. I guess that's why it's $40+ .

I deviated a bit here with mine, and sourced ground and +5V from somewhere closer to the switches, instead of the eeproms own ground and +5V. That isn't the problem, as I moved them with troubleshooting with no change.

Any ideas? maybe an eeprom problem? Why would I have audio in one mode, and nothing in the others? I still get audio from carts in JP mode on the Genesis ( I even tried it with a JP import game).


This will be a killer upgrade, if I can work the bugs out.

Help!

[FABombjoy]

Man, that is weird. No audio at all, huh... Are you able to swap EPROMs with yours and Arakon's to test? Neither of the 2 units I modded had anything like that happen.