How Do The Older Home Systems Have Stereo Out?

Just curious here... I'm starting a project to make something like the X-Neo1 (using a JROK... making my own encoder is on the back burners for now). Looking at the pins on the DIN-8 connector, I see there are pins for RGB, Sync, Mono, Composite, +5V, and GND (which must be used as ground for all of the above)... all 8 pins are used. My question is this... I've read that the older home systems have stereo out. How does the right channel audio get out of the console? Did the earlier systems use a different connector, or was there a pin for the second audio channel before that is used for something else in the newer revisions?

And while I'm at it, what is the +5V intended for? Is that something an RGB monitor needs to see to work properly?

RiotoftheBlood:
Looking at the pins on the DIN-8 connector, I see there are pins for RGB, Sync, Mono, Composite, +5V, and GND (which must be used as ground for all of the above)... all 8 pins are used.

Click to expand...

All? I don't think so: composite serves as sync in RGB cables so that's not used (this was also the case with Genesis/SMS). Of course if you want to use the actual sync pin you can...

RiotoftheBlood:
My question is this... I've read that the older home systems have stereo out. How does the right channel audio get out of the console? Did the earlier systems use a different connector, or was there a pin for the second audio channel before that is used for something else in the newer revisions?

Click to expand...

What you've read is incorrect: No Neos output stereo through the A/V port. You can get stereo only from the headphone jack.

RiotoftheBlood:
what is the +5V intended for? Is that something an RGB monitor needs to see to work properly?

Click to expand...

Yes, that's needed by several (Euro) TV's in order to switch to RGB mode. The fact is that the voltage required by Scart TV's is between 1 and 3V, so you need a resistor in that line (a 100ohm one, usually used by supergun makers, lowers the voltage to about 2V), while the Neo outputs 5V from the A/V port, so the resistor must be put in the cable (I've just made myself a cable that way).

Ahh... thanks for clearing that up. I didn't know that composite could be used as sync either.