MSX 2 (Sony) RGB to Extron Upscaler

[RetroFox]

I'm running into an odd problem that I hope someone else has seen before - I have a Sony HB-F1XDmk2 MSX2 that I'm trying to connect via RGB cable to an Extron DSC301 HD (via the 15pin D-sub input). I've done a bit of searching and believe I have the pinouts correct on both the MSX* and Extron ends. I've tested and re-tested continuity through the lines. All that said, I just can't seem to get a full picture going - I'm getting two of the three RGB colors and only the text mode (I think); the MSX boot logo screen doesn't appear, game screens don't appear. The picture is nice and crisp, there's no rolling/scrolling that I've seen mentioned from other forum posts. Also, the unit's A/V outputs work normally.

 

The odd thing on the 2 out of 3 colors - I can swap the color lines and I'll get the blend of whatever 2 colors I hook up on the first two lines for the text, so it seems the R,G, and B are outputting from the MSX but for some reason the extron is not using/seeing/processing all three colors. I've used this d-sub input on the extron with my Apple IIgs and color/sync works. 

 

*For the 8pin DIN, I'm using the Type A pin out so 6,7,8 pins are RGB and 4,5 are the two sync lines. I also have pin 1 ground hooked up.

 

I'm stumped - is it that I need to use a different combo of pin 3, 4, or 5 for Horizontal/Vertical Sync or is the Extron just not compatible with the MSX output? I know on paper the extron doesn't support 15kHz, but it does and works beautifully with my Apple IIgs. Most of the posts I find on this are talking about SCART connectors/wiring but I really want to make the 8 pin din to 15 pin D-Sub work if possible.

 

Any help appreciated!

[RetroFox]

As best as I can determine, the issue is either that the MSX2 doesn't split Hsync and Vsync, instead just having the Csync signal and/or that the voltage output is too low on one or any of the sync lines and would need at least a capacitor to boost the voltage into a range the Extron recognizes, if not also some kind of circuit to split the Csync into H/V signals.

 

I'm thinking this just not doable without more devices in between, which I'd assume would add greater delay/lag. My intent was to have as few things between the console and tv as possible.