NewHome › Forums › OSSC & OSSC Pro › OSSC – Discussion and support › OSSC to display Sega System 24 medium resolution arcade PCB
xtrasmiley.
xtrasmileyOk I have a working (I think, can’t be 100% sure without seeing it work!) Sega System24 arcade PCB which I am using a HAS supergun with to an OSSC. This is the same setup I’ve used for about 46 arcade PCBs and I haven’t had any issues yet, but all other boards were standard resolution or high like Naomi, but again no problems. This is my first attempt with a medium resolution game.
With this set up I get a sync lock on the OSSC, but get nothing on my TV.
The OSSC screen shows:
423p
24.39kHz
57.66Hz
Which doesn’t seem correct as I don’t think the S24 board is 423p.
Anyway, my TV keeps displaying the “resolution is not supported” message and nothing.
Any thoughts to what settings I should use?
nmalinoskiThose are total line counts of the incoming resolution, not simply visible lines (so 480p will show as 525p, 576p will show as 625p, etc.); 423 lines seems appropriate for 384p.
My assumption is that your display doesn’t like the resolution, refresh rate, or both. Assuming a resolution of 496×384, line doubled, that comes to 992×768, which is not any sort of standard PC or TV resolution. If the OSSC is framing this as 1024×768, that might have better compatibility, but I imagine there are TVs out there that don’t accept this over HDMI.
As for refresh rate, 57.66Hz is enough off-spec from 60Hz that I can see displays outright rejecting it.
You might need something like a Framemeister or Extron DSC 301 HD to scale and framerate convert this to use on your display.
xtrasmileyCrap, thank you for the explanation, are there any settings I can adjust to try on the OSSC?
Any settings that might allow my TV to display it?
What if I bought an EGA to VGA device, like this thing:
xtrasmileyBump, anyone with a way to test some other options or am I totally out of luck with the OSSC and S24?
HarrumphThe scan-rate and number of vertical lines is quite a ways from standard 1024×768 after doubling.
You might have better luck going for WXGA (1280×800). Increase V.Active to 400, Increase H.Active to 640, adjust backporches as needed.
nmalinoskiCould the horizontal samplerate be increased slightly in order to bring that 992 up to 1024?
HarrumphOh I didn’t realise that was the default. Probably the samplerate doesn’t need to be changed, just increase h.active to 512 to achieve 1024×768.
Edit: and if he wants to try 1280×800 like i wrote above, he needs to increase h.samplerate to 780-800.
xtrasmileyThanks for the tips guys, I’ll test it out and post the results!
