stereo on a VA 1 gen. 3?

[zeromutt]

First I would like to thank Lawrence and the many others who have taken the time to posted their knowledge and show their creations on this board. I have been a long time lurker here and I've used the information available to do some basic projects and mods ( p.s.x. , saturn, dreamcast, ect. to a jamma harness, import mods, ect. ). I recently have done the s-vid mod on a genesis 3 ( va 1 ) and it turned out great, the only problem I have is the audio. It seems to have only one audio channel connected to the a/v out mini din. I have read that va 1's have stereo but I have been unable to find any mention of any mods that would need to be undertaken to let me hear both channels ( like segasonicfan's va2 mod. which was a very informative post ). Any help would be appreciated greatly.  


   Phil  

[Segasonicfan]

Hey Phil,
 It has been a long while since I looked inside a VA1 but from what I remember grabbing stereo was much easier.  I believe Sega was nice enough to put both in both op amps.  If you took a hi res pic of the board I could probably help you out

-Segasonicfan

[dynamitepop]

Thanks for taking a look, I have some pics. over at yahoo....I hope this helps.....                               http://qurls.com?i=689

Phil

[Segasonicfan]

Hey Phil,
 Unfortunately those pics aren't much help.  I need HI RES pics, about 1MB filesize of the top and bottom of the PCB to tell help you out.  Photobucket.com is the best site for free pic hosting, they let you have up to 1MB pics too  I can see that there is only 1 opamp though which means the theory will be the same as the VA2.  I've been looking at this old pic on the main GameSX pages for help as well:

http://www.gamesx.com/grafx/gen3over.jpg

I presume the audio signals can be pulled preamp from the row of passive components by the underneath the opamp and above the Oki chip.

If you want to get a head start on the mod look for 2 resistors markes "203" (20kohms) that have traces running from an area near the opamp to the main Sega chip.  The audio signals are usually fed through these values or a "183" (18kohm) resistor.  They are then combined preamp to make a mono signal.
 
-Segasonicfan

[zeromutt]

Thanks for the help, I found where the three audio channels ( L,R,SFX ?) are mixed. Now I just need to get a op amp together. I don't have any broken systems so I may have to buy a LM324 and make one. I haven't assembled any audio circuits, just the basic synch strippers (lm1881N) and the usual resister / caps. on video outputs, so this should be fun. Thanks for the help segasonicfan and if you could just show me a clearer pic. of the board you put into yours it would help me a ton.

Phil