Genesis 3 - Pulling stereo from "mono" model

Started by AG-Wolf, July 31, 2009, 02:00:26 PM

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AG-Wolf

July 31, 2009, 02:00:26 PM Last Edit: February 14, 2010, 04:39:36 AM by 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
"123 years ago, when I was born, this world was a very different place. In those days, we obeyed gravity. Now we defy it."
Pierre Belmondo, CEO of the AG Race Commission. June 8th, 2127

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.
Mida sa loed ? Nagunii aru ei saa ;)

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
"123 years ago, when I was born, this world was a very different place. In those days, we obeyed gravity. Now we defy it."
Pierre Belmondo, CEO of the AG Race Commission. June 8th, 2127

Ace

Quote from: Tiido Priimägi on July 31, 2009, 07:48:52 PM
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 :)
Mida sa loed ? Nagunii aru ei saa ;)

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.
"123 years ago, when I was born, this world was a very different place. In those days, we obeyed gravity. Now we defy it."
Pierre Belmondo, CEO of the AG Race Commission. June 8th, 2127