SSV arcade hardware + OSSC = No Sync

[IcarusFW]

Hey guys, I’m looking for any assistance in getting a couple of arcade boards to display through the OSSC.

I’m currently sorting out my supergun setup, and am running a Pana Twin MP-92 (the one with the mahjong controls) through an RGB SCART cable (made by the Retro Gaming Cables team), and for the most part, the OSSC is working fine with the small handful of boards I own. However, I’m having major trouble with the SSV System hardware – the motherboard set which was made by Sammy, Seta and Visco (http://system16.com/hardware.php?id=817), which features primarily arcade mahjong games and some really jank shootemups – in that the OSSC will not sync with them at all, no matter what I’ve attempted.

First, I’ve attempted to tweak some settings within the “Sampling Opts.” menu, based on some information from this thread: https://videogameperfection.com/forums/topic/ossc-for-pcbs/ . For the most part, this has helped correct some of the scaling issues with the boards that do work, but I haven’t succeeded in getting the SSV System boards to sync up this way.

I’ve also looked at this thread: https://videogameperfection.com/forums/topic/taito-f3-arcade-board-wont-sync-with-ossc-works-with-framemeister/ which suggested tweaking with some settings in the “Sync Opts.” menu, including H-sync Tolerance, V-sync Threshold, H-PLL Pre-Coast and Post-Coast to try an establish sync, but it gets to the point where even my capture card loses detection of the OSSC.

I have tested both the boards and the supergun through the supergun’s Composite and S-Video outputs, and they’re working fine, but obviously I’d prefer to get this all working through RGB SCART if at all possible.

Any help is appreciated.

EDIT: Before I forget, the OSSC I have is on 0.88a firmware. This model of the OSSC does have VGA input, but the Pana Twin supergun does not have VGA out, so that is not an option.

[BuckoA51]

When you say it won’t sync, do you get “no sync” on the LCD, or are you seeing anything at all?

[IcarusFW]

It shows “No Sync” on the LCD on the OSSC, but only with SSV-based PCBs. Other PCBs through my capture setup display fine.

[BuckoA51]

I see, and not a glimmer of sync even adjusting H-sync Tolerance?

[IcarusFW]

Just gave it another try, but this time I factory-reset all settings on the OSSC before doing anything. Tried Mahjong The Lady Hunter first as I knew that worked, and as expected the OSSC picked it up first time.

Tried an SSV System board straight after, and nothing. Tried going in both directions with H-sync Tolerance as you suggested (with everything else on factory reset), and still nothing. I’m assuming it might have something to do with the game’s native resolution, or something?

[BuckoA51]

If it was a resolution problem you’d still get some sync on the OSSC.

Unfortunately the only way to really investigate this further is to break out a scope and see what the sync is doing at low level.

[IcarusFW]

You can probably close this thread now, as I’ve figured out what the issue was: on the Pana Twin, there is a sync dial in addition to the RGB dials for fine-tuning the image. The sync dial on my Pana was at maximum when I got it back from repair originally, which funnily enough worked fine for most of my other boards and on my old TV, so I never really paid it any mind until recently when I needed to get it all hooked up into my capture setup.

So I took a micro-screwdriver and very gently started to dial down the sync dial while the supergun was switched on and connected to the OSSC, and after a certain amount of turning, the picture suddenly appeared, pin-sharp. I’ve done a small amount of fine-tuning, and now the OSSC is picking up all of my boards. I guess the SSV System boards need a lower sync output, otherwise the capture device doesn’t see it at all.

[BuckoA51]

Always be careful when connecting arcade hardware to the OSSC, as it can output sync and other voltages that are too high and out of spec. If in doubt, ask a technician to check the voltages from your supergun.

RetroRGB has done some excellent videos on the topic – https://www.retrorgb.com/testing-audio-voltage-on-an-oscilloscope.html

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