RGB N64 No Signal

[LGuilhas]

Hi Everyone,

I have the 1.6 OSSC since 2020 and has been working great for me on my retro consoles. Recently I decided to complete my collection with the missing N64 and SNES and try to get the best possible image out of these systems upscaled to my 4K tv.

I modded my N64 with Tim Worthington’s RGB kit and ordered the HDRetrovision component cample. While I waited a few weeks for the cable to arrive I sourced locally a cheap SCART cable and used it well both on the SNES as well as the modded N64.

My cable arrived a couple of days ago and while it works well on the SNES to my surprise I got no image from the N64 on certain cenarios. If I plugged in my super mario 64 cartridge which presumably is 240p and adjusted the output for line 5x and optimzed for 512×240 then I got the image. All other options wouldn’t display anything (the input is detected but the TV shows “No Signal”).

If I plugin my ED64, which presumably has the menu in 480i, then I got no image at all. By lowering the analog sync Vth I was able to get an image for brief seconds of my ED64 menu but then it reverted to a black screen and my TV shows “No Signal”.

I figured this was probably due some old firmware bug and as I was on 0.86 I did the HW mod on my OSSC and upgraded the FW to 1.11. Now my SNES continues to work with both cables (the cheap SCART and the HDRetrovision) but my N64 does not output the image even with the cheap cable which worked on 0.86. So I’m at a loss here.

I figure this is something related with strange resolutions but I’m unable to find a solution. Is this familiar to anyone here? Do you have any suggestion on how to get the N64 working with my OSSC?

Thanks in advance

 

[BuckoA51]

Definitely sounds like a bad cable, check how you have your Tim Worthington mod configured (Jumpers JP1, JP2, JP3 open or closed?). Try a csync cable instead (if your mod is set up to accommodate it).

[marqs]

It’s also worth trying with the original composite cable connected to Y-input of AV2 YPrPb. Even though this gives just B/W picture, you at least can test if sync is stable with it.

[LGuilhas]

I’ve ruled out any cable issue and was able to partially solve the problem by downgrading to 0.90 and based on FirebrandX profiles tweak the output and mode to work. In the process i also found that my EDPlus64 was using a 480i signal and for some reason the OSSC doesn’t like that in combination with the cable. I applied a custom OS to it called Altra64 and now i can use any of the cables without any issue.

i did retry to upgrade to 1.11 and use the same profiles but they don’t seem to be working so for now I’ve reverted once again to the 0.90 and it is working as expected. I can’t use any of the 1.xx features but they are not critical to me. But i will retry again when i get sometime as I’m not an ossc expert and this process is somewhat time consuming. But definetly not an HW problem nor a cable problem but rather a combination of weird resolutions and the firmware/settings.

i’ll share if I’m able to fully solve this on the newest version.

[marqs]

Having no signal / sync loss typically results from one of the 3 reasons:

1. Issues with cable / console / mod. In this case OSSC cannot lock reliably to the sync, and it’s apparent by looking at it (red/green LED blinking, numbers changing on the character LCD etc.). Based on your response you’ve ruled this out.

2. Display not being able to reliably lock to OSSC’s signal. With some consoles there is some sampling jitter which makes it way to HDMI clock, and display may lose picture at times or altogether while there are no problem signs on OSSC itself. On v1.11 this can be improved by changing “ADC PLL BW” in sync opt. to lower value.

3. Display not accepting line-multiplied signal. OSSC has limited capabilities for processing the signal, so it cannot e.g. change refresh rate or always produce standard H/V timings. Default Line2x mode is usually most compatible while any optimized profiles have much lower display compatibility.

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