Koryuu s-video interference

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  • #37721
    Noctua
    Participant

    Hello all,

    I recently got my hands on the Koryuu but am running into kind of a roadblock with regards to video output quality. Hopefully some of you can provide me a solution or some more information.

    I’m running a PAL Nintendo 64 through s-video into the Koryuu which is in turn connected with component to my OSSC. On first inspection the output seems as expected. However on a closer look it is quite noticeable there is a pattern of diagonal lines moving through the image. Certain solid colors have it particularly bad (mainly blue and yellow). I’ve seen this before in the past with poorly shielded RGB SCART cables. I believe the idea is that the sync line is experiencing interference (correct me if I’m wrong. Problem is that I’ve tried mutiple cables, both cheap and more expensive ones as well as the official Nintendo cable. Also tried 3 different N64’s. All configurations show the same result.

    From my perspective the issue seems to come from the specific combination of the Koryuu + PAL N64 s-video (50Hz). When running my setup to my Framemeister instead of the Koryuu the image looks perfectly fine. The fact that it looks fine with the Framemeister strikes me as odd.

    Anyone who experiences the same issue? Is the Koryuu ill equiped to handle this specific signal corectly? If so, can this be address with a firmware update?

    Thanks in advance.

    #39460
    leewrigley
    Participant

    Hi, did you get this fixed ever? I have just received mine and have the same bad interference, I know this is probably inherent with the video signal but if there is anything that can be done to minimise this that would be great, also what settings should I be using as the settings from the wiki were not properly syncing the image, thanks anyone

    #39461
    BuckoA51
    Keymaster

    Interesting, was yours a PAL N64 console that you noticed it on too?

    Is this noise consistent, as in the pattern always moves in the same direction, or is it random?

    #39463
    leewrigley
    Participant

    Yea it’s a pal N64 and the noise is pretty bad I do have a photo but don’t think I can attach it here. Also still haven’t figured out a sample rate that will properly sync the image

    #39464
    leewrigley
    Participant

    Btw I finally got it synced at h sample rate 396.65 for whatever reason. Still really bad interference though

    #39472
    BuckoA51
    Keymaster

    you should not need to change sample rate?

    #39473
    leewrigley
    Participant

    Which setting would I change then?

    Sorry I don’t know how to properly describe what I’m meanjng but basically The problem was that the picture was out of phase in multiple areas of the screen (vertical blurry zones down the screen) that would usually be fixed by altering the sample phase but there was no value of this that synced the picture properly, is it h active I would need to change instead?

    This is unrelated to the noisy picture also, that is persistent always it’s seems, kinda looks like a the bad diagonal lines from a noisy SNES but worse.

    #39498
    BuckoA51
    Keymaster

    on the generic sample mode it should not be necessary to change phase like this.. that’s very strange indeed. Did you try moving OSSC off to another input and back again to make it re-sync?

    #39526
    leewrigley
    Participant

    I am using 320 optim mode, was that my problem…? Even using this mode I have it looking really quite sharp.

    Regarding interference.. what are some things that would cause such strong interference because I feel like it get this on a few of my consoles, pretty bad on SNES even using really high quality sheilded scary cables and somewhat aswell on GameCube using the sync on Luna cables. It may be on others but those are what I definitely notice a lot. I would attach an image if you have any way of me doing so.

    #39592
    Noctua
    Participant

    Hello all,

    I spend some more time on this matter to try an narrow things down.

    1. @leewrigley I never noticed any kind of blurriness and did not need to adjust any settings on the OSSC to get a proper picture. Just the interference pattern was a problem for me. Also this problem seems to only occur with my PAL N64 with s-video (multiple cables + consoles tested). My PAL SNES with s-video into the Koryuu has not had any problems and the composite input for everything I’ve tested also lookst great (as much as you can expect from composite at least).

    2. @BuckoA51 For me at least, this diagonal line pattern seems to stay consistent in speed and direction per session. Resetting the console will change this however. Sometimes it’s worse than other times.

    3. I also got my hands on a RetroTink2X Pro recently. I ran my s-video directly into that and the interference pattern was greatly reduced in comparison. Still the tiniest amount was left, but so little that you’d only notice it if you sat 2cm away from the screen. The same goes for the Framemeister as I mentioned in my first post.

    4. I ordered a shielded Nintendo style s-video cable from RetroAccess. I’m still waiting to receive the cable later this month. Kind of a pain to get hold of their cables so I hope it’s worth the wait 🙂 I’m curious if their high quality, high standards cable will do better. If not than I think there is little I can still improve in the chain.

    #39593
    leewrigley
    Participant

    Firstly I think I got the optimal timings *mostly* sorted, I was using 320×240 optim so I think i made it harder for myself instead of using generic.

    Did the svideo cables you use also have a cable for composite also because as far as I can tell from research it is most likely the cable from consolegoods or any other cable with the yellow composite end that will give this kind of interference. Since you said you have a pal N64 I’m curious as to what other cables you tried since it’s not meant to be compatible with svideo. Did you experience blown out colours at all or did you use modded cables?

    #39599
    Noctua
    Participant

    I’ve been using a number of different cables actually. To list a few:

    – Official Nintendo s-video (SHVC-009)
    – Consolegoods cable
    – Generic Amazon
    – Custom shielded from ebay seller

    The Amazon and Consolegoods cable are by far the worst contenders. These are the ones with the composite cable attached. The custom made cable and the Nintendo cable fair a bit better but still with noticeable noise. The latter two are 4-pin din + 2 RCA (audio) only.

    The consolegoods cable was still of use though. Because it was build with PAL systems in mind it came with a 75 Ohm resistor. Because the cable itself sucks, I took the resistor and soldered it into the custom shielded cable. Connecting Luma to ground. The brightness is therefor not an issue.

    I also found that consolegoods claim about which consoles work and which don’t isn’t complete. They state that the Black consoles have s-video support and the coloured ones might not. This is only half true. What matters here is the motherboard revision and not the shell. As far as the PAL systems are concerned:

    Do output s-video:
    – PAL NUS-CPU(P)-01 revision
    – PAL NUS-CPU(P)-02 revision
    Don’t output s-video:
    – PAL NUS-CPU(P)-03 revision
    – PAL NUS-001(FRA) (french system)

    #39600
    leewrigley
    Participant

    Okay, my unit definitely supports svideo, I just know if I buy a super high quality cable I wouldn’t be able to mod it, would I be able to reduce the gain on Ossc to fix the brightness you think? Also do you have a name for the eBay seller for the modded cable?

    #39605
    BuckoA51
    Keymaster

    @noctua Please do let us know how the RetroAccess cable fares!

    #39627
    Noctua
    Participant

    Will do Bucko!

    The seller I got the custom cable from was:
    “retro-ntsc” | Also known as “retro-square-shop”

    Although the cable I purchased is no longer being sold. I can’t be certain cause I haven’t used it but the cable he currently has in stock doesn’t look any better than a generic cable. It even has the composite lead attached. It does come with the PAL required extras such as a resistor.

    As for the OSSC. I will try this tonight and let you know. However I don’t think it will work. When you decrease the brightness on the OSSC I imagine it reduces the amplitude of the incoming luma signal as a whole. And because the signal comming in has already been clipped this will likely not change.

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