Genesis 3 - Pulling stereo from "mono" model

[AG-Wolf]

I am aware that there were two models of the Genesis 3's motherboard, one with stereo, and one with mono... Both Genesis 3 consoles I have are mono models... Does that mean the chips used on the board physically do not create a stereo signal what-so-ever, or are their stereo outputs not being utilized

[Tiido Priimägi]

there is stereo coming on all models, but in those mono systems stereo is mixed to mono... since I have no Genny3 I have no idea what one has to do to get stereo back.

[AG-Wolf]

well I made a little progress, but all I got were the unamplified signals off the Z80 and the L/R YM channels, and then two other traces which were even quieter but seemed like Left and Right separation of Z80 + YM.  They're coming off pins 56 through 60 on the main CPU...

56 - very quiet left or right z80+ym
57 - louder z80
58 - YM L
59 - YM R
60 - very quiet left or right z80+ym

as I said in an IM to Tiido, all of that is sent out to a maze of crap and a quad op-amp.  At the end of the whole shebang, you're left with a mono combination of both channels and z80 mixed with the proper volume levels :/  I did an audio recording as I moved from one pin off the main CPU to the next, but dont have anywhere simple to upload it atm

[Ace]

there is stereo coming on all models, but in those mono systems stereo is mixed to mono... since I have no Genny3 I have no idea what one has to do to get stereo back.

Can't one just use your CCAM circuit to get the Stereo back on a Genesis 3?  I mean, it uses a YM2612 in an ASIC, so I don't see why it wouldn't work.

Man, I'd need to get myself another Genesis 3.

[Tiido Priimägi]

mr. AG-Wolf is already having a CCAM circuit and its just a matter of time when he tries it out

[Ace]

AG-Wolf, what motherboard version is in your Genesis 3?  If it's a VA2, you can simply use this picture I found on SegaSonicFan's website that shows where the sound signals come from, as well as the PAL/NTSC, ENG/JAP region switch locations(not important in this case): http://i18.photobucket.com/albums/b134/Segasonicfan/Gen3Inst.jpg  Just remember that SFX is the PSG sound channel.

If you have a VA1 motherboard, I can't help you.

[AG-Wolf]

I guess I have a VA1 because that chip isnt diagonal on my board... but I thought the first model Gen 3 actually did stereo output without any mod...

I had seen that page before, too, and considered doing the same thing with mine; running one channel through an op amp circuit with the same component values as whatever is used on the motherboard to begin with.  But the SM resistors are so small I can't tell what their values are.