OSSC Pro Expansion out to Hydra Scart – No stable image

[J5]

Hi all, I have my OSSC Pro with the Expansion output connected to via a retrotink VGA to Scart cable connected to my Hydra 2.1 Scart switch and I cant get a usable image from the OSSC when connected to the Hydra. When I use the Retrotink cable direct to my Toshiba RGB modded CRT it works fine. But once I try to switch the OSSC as a source of the Hydra it wont give a good image. If i connect the OSSC to input 7 I believe, if i flip the Switch on the Hydra board I can get a rolling image when using RGBCS/RGBS output. If i switch the expansion output setting to RGsB I get a stable image but its black and white. I fire up CHAT and Gemini suggested i add some  resistors to scart pin 16 output of the OSSC and that was helpul to even get the rolling image I just mentioned. It then suggested I add some more resistance to the Sync and I increased that from the built in 470 Ohm to around 700 ohm and that didnt seem to help.

Does anyone know what is actually the issue here ? I know the OSSC Pro is just fine without the Scart Switcher I want to use, help.

PS I want to use the switcher so i can feed 240p games like NES, SNES, N64, Genesis direct to TV without scaling up to just scale back down. but want to use the OSSC for Gamecube, Wii, OG Xbox, PS2 etc that are 480p or higher systems to output a nice 240p CRT image for no lag gaming. I have a projector that can take 4k input, but the lag is terrible fore any Twitch games were it matters.

 

 

[BuckoA51]

Try toggling the composite sync output on the OSSC Pro. Is the RetroTINK cable including some kind of sync combiner?

 

 

[J5]

Where is the Composite Sync setting found? Thank you

Jon

[BuckoA51]

Expansion opt->Extra AV out mode

[J5]

So i have been told the guy who makes the Hydra Scart switchers does care to help make them compatible with scalers. He says they should only go from Games to TV. So I have connected mine from Scaler to Retrotink RGB2COMP converter and then retrotink COMP2RGB to convert back to scart and that plays nice with the Hydra. If anyone know what I could do my cables to make the signal work without those adapters Id love to know.

[marqs]

Perhaps Hydra’s autodetection relies on status voltage on pin 8 which may not be wired in the VGA-scart cable. You could test manually selecting the input on the switch if such is supported.

[J5]

Switching manually to that input results in the rolling image with Sync on green enabled, no image without sync on green enabled for RGBCS, or black and white image with RGsB and Sync on green enabled.

[BuckoA51]

it’s unlikely that a consumer CRT would support sync on green, this isn’t in the SCART spec.

You could also try Output Opt->CSync combiner see if that setting helps.

[marqs]

It sounds like the switch does not like pure composite sync for whatever reason. I’m here assuming its sync input includes 75ohm termination, otherwise the signal level may be too high for the receiving logic.

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