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 Post subject: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Tue Jan 24, 2017 11:50 am 



Joined: 24 Jan 2017
Posts: 16
Hi. I've recently got into retro RGB gaming and am loving it. Got myself a 20 inch Sony PVM, RGB CSYNC cables and the results are great. One slight hiccup in this is my RGB modded N64.

I purchased it pre modded from a French seller on eBay and it is the 'NUS-001(FRA) PAL RGB officiel CMS' mod. So the early PAL French N64 Mod.

I was advised both a GC and SNES RGB cable will work. I have used both a CSYNC RGB GC cable and a standard RGB GC cable. Both work fine and are a massive improvement over Composite video or S video I was using on my UK N64 prior.

The issue I have is that there is noticeable checkerboarding when I use either of those cables on my Sony PVM. It's most obvious on F Zero X, though present on all games. The CSYNC cable looks exactly the same as the standard version of it. If nothing can be done then I'm fine with it, but thought I'd ask on here to see what can be done. I have no modding skills whatsoever, so hoping a cable solution exists!

I understand checkerboard happens as a result of a poor sync signal. If so, why doesn't the GC PAL CSYNC RGB cable eradicate it, as it has a built in sync stripper/cleaner as I understand it? It's the cable from Retro Gaming Cables, and looks great with my GC.

Research leads me to believe a sync on luma SNES cable wouldn't work, as this French N64 doesn't output Svideo at all. I'll be getting a SNES soon, would a SNES RGB CSYNC cable help with this N64?

If none of the above is a solution, is there a bespoke cable solution that would remove the checkerboarding for me? If I'm told how the cable needs to be wired, I can try and find someone to make it for me, I'm happy to pay for it.

Any and all help appreciated!


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Fri Jan 27, 2017 1:25 pm 


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Joined: 01 Apr 2016
Posts: 381
gravythief wrote:
I was advised both a GC and SNES RGB cable will work.

That's not true! The proper cable for your console is a PAL SNES RGB cable. With a GC RGB cable the picture should be too bright.

To your general problem.
I often read about your problem. For me it seems like that the French N64 with intended RGB restoration suffers from the output circuit. The output impedance to the MultiAV is 39ohms on R, G and B and also on composite video. This means: first you need the additional 75ohm resistors to ground inside the SCART plug. And second, the floating current through the RGB cable is twice as high as in a system with 75ohm resistors to the MultiAV and no additional resistors inside the SCART plug.
I assume that the final N64 design is not designed to perform it and this might cause the checker boarded interference. On my last mod with a French PAL system I haven't observed this problem.
But I have read that it should be helpful if you use a standard PAL SNES RGB cable and cut out the 75ohm resistor from pin 20 to GND inside the SCART plug. In this way you reduce the current floating through the sync-wire.

gravythief wrote:
I'll be getting a SNES soon, would a SNES RGB CSYNC cable help with this N64?

DO NOT DO THAT!!!
I assume that the 12V to MultiAV pin 3 are also restored. So you might destroy your TV set!

It might be usefull if you find a way to get csync from the system and put it on the MultiAV pin 7. Then you can use a 'sync on luma' cable and you will have raw csync.
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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Fri Jan 27, 2017 8:48 pm 



Joined: 24 Jan 2017
Posts: 16
Thanks for taking the time to reply borti, I do appreciate it. I'm glad you warned me away from using the SNES RGB CSYNC cable. I spent ages getting my PVM, the last thing I want to do is fry it!

I won't pretend I follow much of what you describe as I'm not a modder by any degree of the imagination, and I wasn't planning on modding the console further as I cannot find anyone/anywhere to do it. Everywhere online I can find that seems to do modding are not open to orders. However, your advice about the standard PAL SNES RGB cable seems a good option to try. I don't think it's something I can do myself (I'll take a look), but I'll see if I can order a cable with this tweak as you describe it.

Thanks again.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Sat Jan 28, 2017 4:34 am 



Joined: 12 Sep 2012
Posts: 139
Hi,

I have the same french modded n64 as you. I didn't perform the mod myself because I don't have the soldering skills, but I didn't buy the console premodded either. It is my original n64 that I have for nearly 20 years now, I bought the components myself and I paid someone with soldering skills to do the mod for me, and I was there when he did it, so I now exactly what's inside my n64.

So all this blablabla just to say I +1 to everything borti said.
First, are you sure what you are seeing is checkerboard pattern, or dithering artefacts ? The dithering artefacts are visible but not obvious when you use composite video on this console, but when you switch to RGB it become quite apparent, almost disturbing.

Is your monitor PAL or NTSC ? I don't remenber ever having seen cherckerboard pattern problem on a PAL set, because it should be made to handle it, whereas NTSC sets have more problem with this.

As borti said, the best cable you can get for your n64 is the PAL SNES RGB cable. If you can find an official one, that's great.
Do not buy a CSYNC cable because as bordi said, if the guy did the mod entirely, the csync wire will be wired to the 12V inside the console and that can be pretty bad for your tv.
Do not buy a sync-on-luma cable either, because if the guy did only the rgb mod, the stock french n64 does not output s-video. It's possible to mod the console to ouput s-video but it's quite tricky (need some soldering on a chip pads), mine is modded for s-video too. I suppose it should be possible to mod the console for csync too, but I never investigated in this.

For the 75ohm resistor cutting thing, I don't think that's really necessary because the PAL SNES and the PAL N64 both have a 75 ohm resistor in their stock composite cable, so the consoles should be able to handle it.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Sat Jan 28, 2017 11:19 am 



Joined: 24 Jan 2017
Posts: 16
Thanks Joe. My monitor is a Sony PVM 20M2MDE, which is a European version but my understanding is it can handle both PAL/NTSC signals anyway. I do notice the pattern much more on this monitor vs. my 15" consumer CRT, but I assumed that is simply because of the much better, more detailed and clearer picture of the PVM, which makes it stand out more.

I'm pretty sure it is checkerboarding and not dithering, as I notice it in areas of solid colour and there isn't movement on edges like I think there is with dithering? Also it is most noticeable on F Zero X (the track surfaces mainly) which I understand to be where this checkerboard effect is most obvious. I do see it in other titles (e.g. Perfect Dark) but nowhere near as much and it doesn't bother me. Only F Zero X bothers me which I can live with, but it's a shame as that game is awesome!

I will try the standard SNES RGB cable as you both suggest. I'm struggling to find an official one from a quick search. Would the ones that Retro Gaming Cables sell be ok? They sell high quality RGB cables for all consoles, so I presume there won't be anything fundamentally different vs the official one? I'll make sure I avoid both the sync on luma and CSYNC variants.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Sat Jan 28, 2017 5:13 pm 



Joined: 12 Sep 2012
Posts: 139
Hum, you are making me doubting even more. The track of F-zero X is a good example of the console dithering. It's more obvious on plain color surfaces and it's static.
Here is how my n64 looks like (through official SNES PAL cable, but my n64 is modded to output sync-on-luma, and through an OSSC + DVDO vp50pro) :

Image

You can see the dithering pattern is different between the grey area and the purple area, whereas cherckerboard pattern due to bad sync tends to be consisten accross the screen.
Here you can see OOT running through CEN64 (a cycle accurate emulator) and in the intro the dithering is quite obvious :

CEN64: Legend of Zelda, The: Ocarina of Time

For the cable, I don't know the quality of Retro Gaming Cables, but the "Super NES RGB SCART (PAL) wired for composite sync CSYNC" should be fine. Be careful to ask them if the sync wire is wired to the composite video output of the n64, and how their sync cleaner inside the plug is powered : if it's powered by the 5V it should be fine, but if it's powered by the 12V it can be problematic because if the guy who modded your console did it well, there should be a 10kOhm resistor on the 12V and there is not enough current to power the sync cleaner.
Retro consoles accessories on ebay is making good cables too (especially if you buy the coaxial pro cable option) but I think she is making only sync-on-luma cable, so you'll have to ask her to do a special item for you.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Sat Jan 28, 2017 5:46 pm 



Joined: 24 Jan 2017
Posts: 16
Ah ok, maybe it is dithering that I have then. I think it does look like what you show, though I'll need to check it to be certain (don't have access to it at this moment). If that's what yours looks like with CSYNC then maybe my N64 is fine, and I'm just expecting too much from the signally impaired console!

I'll go for the SNES RGB PAL cable anyway, as it sounds like I'm wrong using the GC one. I'll drop the guy a message with the info you've provided, just to see if I'm able to get the CSYNC variant to work with my N64, but otherwise I'll just go with the standard one (sync over composite video) to be safe, given the previous comments about the potential for a CSYNC SNES RGB cable from my N64 to fry my TV.

Thanks again to both of you for your comments, they've been very helpful.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Sat Jan 28, 2017 5:56 pm 



Joined: 12 Sep 2012
Posts: 139
Here is another example, through ultraHDMI this time, and it looks like what I have :

F-Zero X Custom Track: Uranus [N64 UltraHDMI 4K]


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Wed Feb 22, 2017 8:33 am 



Joined: 24 Jan 2017
Posts: 16
I just thought I'd update this thread for anyone browsing it in the future.

First of all when I mentioned in my original post about using a SNES PAL CSYNC cable, what I actually meant was a PAL SNES RGB cable with a built in Sync separator that gets CSYNC from the composite video signal. I didn't mean a SNES RGB cable that is wired to take CSYNC direct from the console, which is the NTSC SNES RGB cable. Hence the warnings above about frying my TV!

I can confirm that using the PAL SNES RGB cable with Sync separator from Retro Gaming Cables is fine:

https://www.retrogamingcables.co.uk/nin ... SYNC-CSYNC

This has not fried my TV and the picture does seem a little less garish compared to using the GC RGB cable, so this is now the cable I use.

Finally I can also confirm what I'm seeing on F-Zero X, and to a lesser extent other games, is in fact dithering and not a checkerboard effect due to Sync issues. Thanks Joelepain for putting me straight! I think it is much more noticeable since acquiring the RGB Modded N64 and getting a Sony PVM as the picture is a thousand times more clear than it ever was using Composite on a consumer grade CRT.

I've now accepted this and am just enjoying playing my N64 games with the best signal I can get!

Thanks for all the help.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Thu Feb 23, 2017 10:41 pm 


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Joined: 18 Jan 2017
Posts: 16
I also faced the checkerboard issue with both SNES and gamecube (both PAL). I certainly will with my N64 (also NUS-00(FRA)).

For the Gamecube I solved the problem adding a SYNC STRIPPER into the cable.
For the SNES I turned my official cable into a SYNC on LUMA cable, because it just requires swapping two wires of the cable connector.

I will probably use one of this two solutions when my N64 is RGB-modded.

What would be awesome, would be to direct CSYNC from inside the console to pin 9 instead of composite video on the multi AV out. A PAL console could have both CSYNC and the 12V. Regular cable would do the job just fine and no SYNC STRIPPER would be needed. It would also be awsome for PAL SNES too (playing with gamecube motherboard seems to hard for me).


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Wed Jul 11, 2018 10:21 am 


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Joined: 18 Jan 2017
Posts: 16
chomel wrote:
For the SNES I turned my official cable into a SYNC on LUMA cable, because it just requires swapping two wires of the cable connector.

I will probably use one of this two solutions when my N64 is RGB-modded.


I just realized sync on luma is not possible for a PAL N64 as the console (the NUS-001(FRA)) doesn't outpout luminance and chrominance.


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 Post subject: Re: N64 RGB PAL NUS-001(FRA) Checkerboarding CSYNC
PostPosted: Wed Jul 11, 2018 1:29 pm 



Joined: 12 Sep 2012
Posts: 139
chomel wrote:
chomel wrote:
For the SNES I turned my official cable into a SYNC on LUMA cable, because it just requires swapping two wires of the cable connector.

I will probably use one of this two solutions when my N64 is RGB-modded.


I just realized sync on luma is not possible for a PAL N64 as the console (the NUS-001(FRA)) doesn't outpout luminance and chrominance.


In fact the RGB Amp of the FRA model output S-Video, but it's not wired to the multiout. That's another mod you can do (but it's not really documented on internet). I did it with my N64 and it's working great.
If yours is not RGB modded yet, you could ask the modder if he can do it too.


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