[Noctua]

Hi,

So I tried multiple times to capture a good example of the problem. The video captures look pointless so I’m not going to bother showing it. The best I was able to capture can be seen with thist link: https://imgshare.io/image/20201015-2120081.NxfSiO

This is the File Select screen from Mario Party 3 which has a dark blue background and is a worst case scenario. You can clearly see the diagnal lines in the blue shade. Now try to image that they are moving as well. The direction and speed can change over time.

I suppose the pictures of the second link are closest. Though it seems to effect the entire screen there. On my end it’s only certain large shades of color.

The S-Video cable I use has proper shielding and most definitly uses a 750hm resistor as there is no brightness issue. I’m unsure if the capcitors are necessary. I’ll see if I can open the AV plug and check what components they added. Maybe that is to blame here. Still think its weird that the Retrotink MINI’s auto comb filter completely solves the problem though.

[Noctua]

@megari I’ll see if I can get some good footage of the problem tonight and will post it here. I suppose I yelled Eureka! to soon. The fact that s-video shouldn’t need a comb filter makes a lot of sense when you put it that way. Goes to show how much I know.

Noise like this is always hard to properly describe. What I’m seeing is kinda like the pictures leewrigley posted. Diagnoal lines going through the image. However on those pictures it almost looks like it effects the entire image. On my end it’s only showing on specific shades. For example. The red and yellow text on the Pokemon Stadium title screen as well as Psyduck’s head. The other parts of the image look pretty much fine. I should also note that using other s-video sources with the same cable are fine. Using my SNES for example shows a perfectly clean image with the Koryuu. Composite sources also look fine (at least as good as composite can look that is).

Due to this I thought maybe my N64 was faulty, so I tried another one with the same board revision and one with an earlier board revision. Both show the same issue.

I’ve used a bunch of different cables for this. Started with the consolegoods.co.uk PAL modified s-video cable. This one wasn’t to great. Poor shielding and such. I’ve also tried the official Nintendo cable (NTSC), retro-access.com (NTSC), and classicgamestore.ch (PAL). These don’t have the yellow composite RCA lead. For testing the NTSC cables I’ve soldered a 75 Ohm resistor between Luma and ground on the console motherboard. The latter two cables are built really well and perform otherwhise excellent.

Now I’m thinking that maybe it could be a crosstalk problem. But not caused by the cable bu by the console itself? The PAL N64 doesn’t look like it was supposed to even have s-video support. It seems more of a leftover that they wanted to omit but didn’t for whatever reason. The fact that later board revisions and french systems flat out don’t work when you hook up an s-video cable says enough. Maybe the fact that the RetroTink MINI’s “auto” comb filter solves the issue is a necessary evil? Even though s-video normally shouldn’t need it?

[Noctua]

Hi leewrigley,

I actually own the classicgamestore.ch PAL N64 S-Video cable. I can tell you that it is by far the best cable I’ve used so far along with the NTSC RetroAccess cable. These two are mostly identical accept for the PAL modification and the mold for the Nintendo Multi AV plug being slightly different.

I assume you mean for the component cables to go from the Koryuu output. This will likely not change anything unless your current cables are garbage. I tried to compare cheap and thin RCA composite cables to professional component cables. The results were hard if not impossible to distinguish from eachother. However, if you’re chasing perfection like me, it could still be worth it.

I strongly believe that the Koryuu’s comb filter is to blame for the dot crawl noise. I’m unsure if the developer reads these forums. BuckoA51 is one of the Keymasters. Maybe he knows if he reads this?

[Noctua]

Okay, I haven’t shared any information in a while. It has been quite busy, so my apologies for that.

Anyway.
I strongly believe I now understand where the interference or “dot crawl” is coming from. I think it has to do with the comb filter of the Koryuu. Testing multiple configurations with different equipment, this is the conclusion that I keep returning to.

* Using High quility shielded S-Video cables from RetroAccess (both original and modified for PAL N64)
* Using multiple revisions of the console
* Using different settings on the OSSC
All result in a noisy image

* Using a Framemeister, Retrotink 2x Pro, Retrotink 2x Pro to OSSC (VGA)
All result in considerable less, but still somewhat noticeable dot crawl. Maybe because the Koryuu has a sharper image/signal?

The “a-ha” moment came as soon as I used the new Retrotink MINI. This device has two options for its comb filter. Auto and Retro. The website states that this device has been built in such a way that it supports N64 PAL consoles over s-video (both normal and PAL modified s-video cables seem to result in the same image). Also saying that if there is any dot crawl present in the image that you should switch to the “auto” comb filter. This proved wonders. The image with this device + s-video with the “auto” comb filter, is the cleanest I’ve ever seen my unmodified PAL N64.

However, due to what the Koryuu is, I believe that with an adjusted comb filter for this device it can look even better than the Retrotink Mini. Especially when connected to the OSSC. Is it possible for the developer to look into this comb filter issue and change it with a firmware revision?

[Noctua]

Hi leewrigley, sorry for the wait. I have done some tests with the OSSC control. But as I expected I was unable to get the overbright image to the proper levels. When adjusting either the pre-ADC gain or the Y’ input Offset or Gain I can adjust the brightness to my hearts content but it effects the whole picture. The problem with the N64 PAL s-video output is that the highlights are clipping and becoming the same brightness value. I’m afraid I don’t have any tricks to tackle this problem. It seems to only solution is to use a 75Ohm resistor on the N64 Luma output. Maybe we have some OSSC genius around who knows a better solution 🙂

I’m currently still waiting on the RetroAccess cables. I’ve received confirmation recently that they shipped the cables. Now I’m waiting for my overseas US address to receive it at which point I can send it to my home address.

[Noctua]

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.

[Noctua]

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)

[Noctua]

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.

[Noctua]

Hello leviathan,

Which model of N64 are you using? Reason I’m asking is because I now there are certain N64 models that don’t output s-video. From my experience plus from what I’ve heard the compatibility is as follows:

DOES output s-video:
– NTSC
– PAL NUS-CPU(P)-01 revision
– PAL NUS-CPU(P)-02 revision

DOESN’T output s-video:
– PAL NUS-CPU(P)-03 revision
– PAL NUS-001(FRA)

The NUS-001(FRA) or comparable modelnumber can be found on a sticker on the underside of the console. The CPU revision numbers have to be checked by opening the console where it is printed with white text on the motherboard. The French (FRA) models are special because they can be modded to output RGB. No other PAL console can do this. Not in the same way at least. The problem is that those French consoles don’t have the necessary components to output s-video. Same goes for the CPU-03 board revision consoles.

Take care!

[Author]

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