240p passthrough works fine but line2x does not

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    I just got my OSSC and it works great for Saturn, Dreamcast, and my RGB-modded N64 and PC-Engine Duo R. I’m having significantly more trouble getting it to display NESRGB, SNES, Genesis, and Master System. My TV is old, a Magnavox 37MF331D made in 2006, but it supports 240p and all of my RGB systems work fine when hooked up through a BA7230LS RGB->component circuit or when using passthrough on the OSSC. Also, I still get audio when using line2x even though my screen blanks. I’ve tried multiple confirmed working HDMI cables direct to my TV, and I’m using original power supplies and RGB cables from Retro Console Accessories, and they’ve always worked well for me.

    I tested on my PC monitor and it displays SNES fine (as expected) and I tried another TV that was able to display the SNES signal but had frequent sync drops. The second TV was also able to display Master System without trouble when using line2x, so I assume the OSSC itself is working properly as well.

    Since my main TV supports 240p and can handle the refresh rates of all my consoles, I thought I wouldn’t have such trouble getting the line2x to work. Could my TV be more sensitive to out-of-spec refresh rates on 480p than 240p? Are there any settings I can try changing that might help, or are there any devices I can try adding to my setup?

    Thanks for any ideas!


    Does your TV actually support 240p over HDMI, or does it think it’s 480i?

    The NES and SNES are known to have imperfect sync signals, and I want to say the Master System and Genesis have their own sync issues; so, if you don’t have a NESRGB with a separate dejitter mod, or a NESRGB 1.x with the latest firmware (trades palette selection for dejitter functionality), or a 2.0 or newer NESRGB (has dejitter built in), or a dejitter mod or a combo RGB bypass/dejitter board in your SNES, then I’d say it’s possible that your TV has different processing algorithms for SD, ED, and HD content, and janky sync is what’s causing you problems with ED/HD modes.


    My TV is reporting the 240p passthrough as YPbPr and not 480i, and I can’t tell the difference between the passthrough and the RGB->component converter picture-wise. I’ll have to look into a dejitter board for SNES and see if that fixes it, and go from there with the rest of the consoles.


    It is really rare for a TV not to support 2x mode, do you at least get the test card image?


    I get the test card when I turn the OSSC on. I’m not really sure what happens when I use one of the consoles I’m having trouble with. I can switch back and forth between passthrough and line2x and sometimes it will display a garbled frame of line-doubled graphics but freeze on the screen, and it isn’t coming live from the console. It’s just some random frame that it somehow still has in memory or something, usually with the image rolled halfway up the screen. Sometimes I also get the test card when I switch to line2x.

    Line2x works fine for some systems like I said, but I hadn’t read of any sync problems with Genesis so I’m surprised it isn’t working either.

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