Time for another Aiwa Mega-CD experiment! The revision 2 02-01 mainboard is the only one of my two Aiwa mainboards passing power through to the Game Unit section at the moment, so I’m using it to test both Game Units. That’s right, including the one I borrowed the Mega-CD BIOS chip from and previously fitted with a socket.

The other mainboard may have a faulty switch somewhere in its power path, but I’m still investigating that. I’ve also noticed that neither board is giving me proper amplified sound with the revision 2 audio and microphone boards, so there’s still quite a bit to sort out. I’m wondering whether a transistor or something further along the audio path might be responsible.

First up is the Game Unit I’ve already been repairing. I’ve got it connected to the 02-01 mainboard, with Sonic ready to go. And there he is! The display is working, even if my camera doesn’t seem particularly interested in showing the correct shade of blue.

Next I swapped in the other Game Unit, the one that’s had the trace repairs and BIOS socket work. I was rather keen to see whether the BIOS chip was still doing its job, and thankfully I managed to get the Mega-CD BIOS screen. That is good news!

There are still some patterns and interference running through the picture, though, and the audio problem hasn’t gone away. It might be the Game Units needing more capacitor work, interference from having the Aiwa scattered across the bench, a supply problem or something else entirely. I haven’t worked that out yet.

Still, both Game Units have now given me something useful to look at on the same mainboard. Not a bad result for a collection of parts that’s been fighting me for so long!