[Nrg]

Sure. It was 75 ohm resistor, but that was chosen totally randomly, meaning it was the smallest one I had available. I’m going to try different values in the coming weeks when I get my order from the electronics shop delivered, so I have different resistors to try.

So 75 ohms was enough to fix the problem. I think smaller is probably enough.. I’ll find out.

[Nrg]

Ok, mystery solved. Problem definitely was/is the Sony S-RGB transcoder. Basicly the svideo signal had too big voltage level for the Sony to handle, so it got all confused and lost the sync on all-white scenes.

I fixed it by adding some extra resistor on the luminance (Y) signal of the svideo cable to drop the voltage level. After that all-white scenes started working perfectly fine and the Sony transcoder doesn’t mess up the signal anymore!

[Nrg]

I just tested that (plugged composite video from C64 to Y-input of OSSC), and that works fine. The all-white scenes don’t cause any kind of trouble.. so that means it’s the Sony transcoder that gets messed up ?

If someone else wants to test aswell: I used a demo called Comaland (by Censor Design and Oxyron) for C64 (http://csdb.dk/release/?id=133940). You can see the issue after around 2 mins when running the first floppy of that demo (image1.d64).. there’s the scroller with all-white background, which totally messes up the sync/signal when using the Sony Transcoder with OSSC (OSSC display shows all kinds of weird signal infos during that time period and you lose the video).

[Nrg]

I wonder if those “white-issues” are related to the fact that C64 is known to have “too high” analog levels in the svideo output? That’s why one needs to have extra resistor in the circuit.. so even more attenuation is needed perhaps?

[Nrg]

Yeah, it seems I have the same problem. After all-white screen on the C64 signal OSSC display shows really weird values for a while until it stabilizes again.. I assume the Sony transcoder gets confused for some reason..

[Nrg]

That got me thinking.. and that was spot on. I have multiple SCART cables, and I was accidentally using the one which doesn’t have RGB pins wired up.. so the TV was displaying composite video, and OSSC was only getting the sync signal, no RGB video.. aargh, I feel so stupid right now 😀

So mystery solved.. after changing to proper RGB SCART cable and I can now see the actual video thru OSSC, in both X2 and X3 modes!

Thanks a lot and sorry for being stupid. Sometimes the solution is too obvious..

[Nrg]

Thinking more about it.. actually I do have an Amiga here. So I connected Amiga composite video output to the Sony S-RGB transcoder, and the Sony RGB SCART output to OSSC. Same problem, OSSC detects the signal correctly (49.92Hz refresh rate etc), but the video output is all black/empty..

And if I connect the Sony transcoder directly to TV using RGB SCART, the TV displays the video just fine, no problems there..

So it seems OSSC is somehow incompatible with the Sony S-RGB transcoder.. because it fails with both the C64 and Amiga signals. Any idea what might cause that?

[Nrg]

I don’t unfortunately have other “consoles” atm here. But like said, if I connect the transcoder directly to TV using RGB SCART, it all works fine!

[Nrg]

Yes, after changing the H-PLL values the led changes to green.

I’ve tried both X2 and X3 line modes, but the end result is the same with both; output is all black/empty.

[Author]

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