Well, the me of the past didn’t do such a good job of removing that BIOS chip… but the good news is, we can rebuild him! We have the technology! If only I had my Hakko 808 back then! :)

The MPR-15768-T ROM had been removed for the earlier BIOS dump. Unfortunately, my original removal attempt had damaged some of the connections around the chip. Now that I’ve got the game unit apart again, it’s time to find out just how much repair work I’ve created for myself.

Looking at the underside of the board, things aren’t quite as terrible as I first thought. Most of the pads are still there, although there has been some unfortunate work with a heat gun. The top side is another matter, with several damaged connections that will need a closer look. Wonderful. At least I’ve got a better idea of what went wrong.

The plan is to install a socket where the original BIOS chip used to live. That should make it considerably easier to swap ROMs without repeating this little adventure. I’ve already dumped the original BIOS, so there is also the possibility of trying a modified region-free version later on.

I spent a fair bit of time following the connections around the board with the multimeter. Some traces head underneath neighbouring chips, while others disappear off towards different parts of the game unit. I’ll need to work out exactly where the damaged connections should go before attempting any repairs. A few little wires and some patience should do the trick. Hopefully!

There are plenty of electrolytic capacitors in this unit too. Most appear to be 10 uF, with some larger values scattered around the board. The backup battery was only showing around 0.4 V, so that will need attention eventually as well. One job at a time, though, because this BIOS socket is already looking like enough entertainment for one afternoon.

I also wondered whether the game unit could be powered independently from the rest of the Aiwa system. It has its controller ports, AV output and the connections that normally run up to the CD section. Finding the appropriate power connections might make testing a little easier, but that’s something to investigate rather than assume will work.

For now, I’ve established that the damage isn’t quite as hopeless as it first appeared. The socket and trace repairs are the next part of the job, and with a bit of luck we can get this poor Mega-CD game unit back into action.

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