Looks like I will need to use a fourth GBA/N64 switch, . The N64 is stereo, the GBA is mono. When you connect up the GBA it only plays on one speaker, to get sound from both speakers you have to connect the mono signal to both speakers. If you leave the wires as this, the N64 will get one of the channels with both left and right speaker signals; so this fourth switch is needed to enable mono on both speakers but cut this when in N64 mode so you get the proper N64 stereo signal, rather than one of the speakers being combined.
Not an issue.
The other thing is that I have a main on/off button so the power can be in the console but off; however if the GBA/N64 switch is left on GBA mode then even when the system is off, the GBA will get its 3v from the two batteries (in N64 mode, it won't). I therefore need to use an on/off switch which also connects to the GBA 3v supply; so:
1) main on/off switch is off, GBA gets no power.
2) main on/off switch is on, in N64 mode, GBA gets no power.
3) main on/off switch is on, in GBA mode, GBA gets power (both contacts connected).
This is easily done via my 2 switch system.
These are the switches I am using. The larger one is the main on/off one and the smaller ones (4 needed) all connected together as one switch - either in 2 x 2 setup or 1 x 4 block; not decided yet which.
As I said before, I won't start on the case construction until I have everything completely done and fully tested. It is a slow process, but I have to do small steps at a time so I can easily resolve any issues as they creep up.
Just had to buy another one, $82 (about £42). Will take about 2 weeks or so to arrive.
