How to wire a Saturn SCART cable to VGA

[eastbayarb]

I have a NEC XV29 A+ Presentation Monitor (27") which can handle 15khz and 31.5khz signals. It has S-Video, composite video, and VGA inputs.

I just got a Sega Saturn SCART cable. How would I go about modifying the SCART cable to connecto to the VGA input of my monitor?


did a search here and through google but no luck

[MonMotha]

My normal method is to hack off the SCART connector since (here in the USA), SCART sockets are almost impossible to get hold of in small quantity.

You'll have an orange, green, blue, yellow, and (usually, measure 5V with a multimeter to the black ground wire) brown wire:

Orange = Red
Blue = Blue
Green = Green
Yellow = CVBS (composite video with sync info)
Brown = 5VDC
Black = Ground (video and power)

There will also be some other wires that you don't need (white and red, for example, are audio).

I usually tie the shield to ground as well.  This is optional, but can improve noise immunity (or hurt it, if the rest of your ground sucks).

You can try just hooking up the RGB lines to an HD15 VGA connector (pins 1-3 = RGB in that order, pins 4, 6-8, and 10 are ground.  If the device outputs sync on green (some do, some don't), some monitors (especially high end ones) will happily sync up.  Heck, some will even manage to reconstruct resonable sync from nothing but the blanking pulses!

If that doesn't work (and it often doesn't), get an LM1881 and rip composite sync off the CVBS line:
LM1881 Pin 1 - VGA Pin 13 (horizontal/composite sync)
LM1881 Pin 2 - CVBS from SCART through a 0.1uF capacitor
LM1881 Pin 4 - Ground
LM1881 Pin 6 - 680k resistor in parallel with a 0.1uF cap to ground
LM1881 Pin 8 - 5V from SCART

The other LM1881 pins can be left unconnected.

It's also a good idea to put a 0.1-1uF cap from ground to 5V near the LM1881 chip to clean up the power.

This will give you a valid composite sync signal off the CVBS line.  Note that devices which run progressive scan (30kHz, such as a PS2 in that mode) usually turn that line off, so you'll get not sync info then.  If that's the case, you can try using the green line instead of CVBS in case sync on green is present.

I have this wired up on a donut board (along with another chip to give me separate sync, which my Kortek seems to really prefer on PS2 signals) zip-tied to the end of a (formerly, until I cut the end off) PS2 SCART cable.  Works great on any monitor that supports 15kHz horizontal.

[eastbayarb]

Interesting info but do you have any pictures of what you are talking about?

[MonMotha]

I don't have any handy...  Are you wanting schematics or actual pictures of the final result?

[eastbayarb]

both would be cool...or maybe if i sent you a scart saturn cable and vga connector, maybe for a little $$$ you can wire it up for me ?

[MonMotha]

I can draw up a schematic for you when I get the chance.  A picture of the finsihed piece will have to wait as my digital camera isn't handy.

If you'd like me to wire it up for you, I have no problem with that.  I can also buy the parts.  PM me if you're interested, but I'll be up front and say that this isn't too complicated (the soldering skills for the HD D-Sub connector are the hardest part, and even that isn't bad).

[Frosty]

Hey, I'd also be really interested in some pics, too.  I'm hoping to get both my Saturn at some point, but more importantly, my Genesis hooked up to my arcade monitor.  The Genny Model 2 AV pinout is much the same (R, G, B, G, and composite video w/ sync), but uses a 9-pin DIN connection.

Of course, the monitor monitor has separated wires for H/V sync.  I'm assuming that an LM1881 circuit is required to make this work, correct?  But, outside of that--the process can't be that much different for the Genesis as opposed to the Saturn...

Thanks!

[MonMotha]

From the looks of that connector, you've already got composite sync available (pin 5).  Just hook that up to either the horizontal or both the horizontal and vertical (depending on what your monitor desires) and it should work.  Very few monitors actually require separate sync.

[shess]

I found this site very useful when trying to put consoles in a cabinet.  http://www.mameworld.net/pc2jamma/  .  There is a link for saturn to jamma as well as other stuff to jamma.  If you don't use Jamma it's still good info because he has a diagram and info on building the circuit to get composite sync out of the composite video from the scart cable.