nfg.forums

Quote from: Link83 on September 18, 2009, 07:38:43 PMExcellent work DarthCloud! 
...
I think way can safely say the main required component for RGB from the 'S-RGB A' chip is one 75ohm resistor in series on Red Green and Blue - and of course a standard NTSC RGB cable with 220uF capacitors aswell.

My FRA RGB modded N64 pcb is gued, so I can't exactly see how the S-RGB A mod is performed, but if I use the 220uF capacitor RGB cable I get the same effect as with a PAL SNES; the screen turns dark after a few secs.
Is this mod performed differently then, or was the perception that it should have caps incorrect?

EDIT:
This is likely the (complete) missing components ('factory') mod, which Link83 and kwyjibo mentioned will not work with a 220uF rgb cable.

The SNES rgb cable I ordered from consolegoods just have 75 Ohms shunt resistors over every video line.
That means 75 Ohm in parallel with signal and goes to ground.

Quote from: Link83 on September 18, 2009, 07:38:43 PM
Excellent work DarthCloud! 

Looks a lot like how I thought it would, although i'm a bit surprised by the C-Sync line as I was expecting the 'S-RGB A' chip to output C-Sync on Pin 18 (Although I guess it still could, but maybe not used by Nintendo - although thats a bit unlikely)
Would be great to get some accurate capacitors values though if possible 
I think way can safely say the main required component for RGB from the 'S-RGB A' chip is one 75ohm resistor in series on Red Green and Blue - and of course a standard NTSC RGB cable with 220uF capacitors aswell.

For anyone interested in understanding the remaining components after the 'S-RGB A' chip the diodes are for ESD (ElectroStatic Discharge) protection circuit (Thanks Viletim for that info) so they are not entirely necessary unless you plan on hot-swapping cables, or rubbing you feet on the carpet and touching the connectors! Also, the final small value capacitor to ground should be for EMI (ElectroMagnetic Inteference) like a ferrite bead, so it varies if its worth adding or not.

Got these guides from Assemblergames:

Quote from: rogerhanin2002;609174it seems there is a pretty perfect MOD for NUS-001(FRA) N64

sorry only in german
http://free-for-all.ath.cx/daten/n64rgbmod.html#fra-pal

or in french
http://pakupakustory.blogspot.fr/2011/12/docteur-switch-en-direct-de-latelier-le.html

But you already mentioned that the Free-For-All guide has the wrong components. Still need to read the French guide myself. From my gued FRA RGB N64 I can see it has at least 2 39 Ohm resistors.


EDIT:
French list of components:

Quote3x SMD transistor BC stamp, type 818-16, housing SOT23, base N, NPN, 25V, 0.5A, hfe 100-250
3x SMD chip resistor 1206, 75 ohms (recommended 0805 or 0603)
3x SMD chip resistor 0805, 39 ohms (recommended 0603)
1x SMD chip resistor, size 0805, 10k ohms (recommended 0603)
3x SMD Chip Capacitor, 0603 footprint 47pF
1x SMD Mini Melf Zener diode, 12v (Recommended Melf or micro SMD chip zener diode 12V BZX284C Conrad SKU: 148822-62).

As opposed to the Free-For-All German list (which was wrong according to Link83):

Quote3x Transistor SMD NPN SOT-23 25V 1A 0,25W
3x SMD 1/4W 75 SMDChip Resistor, package 1206, 75 Ohm
3x SMD-0805 39,0 SMDChip Resistor, package 0805, 39 Ohm
1x SMD-0805 10,0K SMDChip Resistor, package 0805, 10 K-Ohm
3x NPO-G0603 47P SMD-Multilayer ceramic capacitor 47P, 5%
1x SMD ZF 12 Chip-Zener-Diode 0,5W 12V

Wow, no update at all on our FRA N64 RGB topic?  :O
Hope to try the SNES jr mod on my FRA N64 the coming period and confirm it working with a GameCube RGB cable!

Quote from: Link83 on September 15, 2009, 12:31:51 AM

Quote from: roccoOk, do you recommend to go with the known NTSC RGB mod including the amplifier instead on those early french models??

Well you can go that route, but it seems a bit of a waste given the fact this French N64 already has a video encoder chip that amplifies and outputs RGB - the 'S-RGB A' chip. I would first try the SNES 2/Jr RGB mod thats already in the Wiki here:-
http://gamesx.com/wiki/doku.php?id=av:snes2rgb

Since that also uses the 'S-RGB A' chip aswell it should work when used with an RGB cable using 220uF capacitors. However, what im hoping is if DarthCloud can make a layout/schematic for the video components on this NTSC SNES then we should know 'for certain' what components and values we should be using for this French N64 and the SNES 2/Super Famicom Jr.

So, the way I see it, you have three choices:-
- Use an RGB amp directly from the 'VDC-NUS' chip
- Try the SNES 2/Jr RGB mod from the 'S-RGB A' chip
- Wait and see if DarthCloud has any success mapping out the video components so that we know for certain whats needed to perform the mod.

I hope that helps 

Can anyone comment on their experiences with this? I forgot to make a note myself (or can't find it anymore), but it seems that the SNES Jr RGB mod on the FRA N64 has the same issue as the early PAL SNES revision with the PAL GC rgb cables (220uf caps), and the screen being/turning black.

I can confirm this currently:
- using the VDC-NUS + (THS7314) amp on the FRA N64 my PAL GC RGB cable works
- I have a FRA N64 where the missing components are added (but can't confirm which exactly due to being gued) and the screen turns black with a PAL GC RGB cable


Somewhere I read someone mentioned that the missing components mod basically results in the same RGB output as the S-RGB mod. Can someone confirm/deny that? If it's true, that might explain why both result in a black screen with a PAL GC RGB cable. On the other hand, why do such cables work with the 1CHIP SNES??

EDIT:
For the latter, I wonder if there could be a difference between the S-RGB (BA6595F) and S-RGB A (BA6596F) chip...

EDIT2:
Ah, here I seem to claim the S-RGB FRA N64 mod gets a black screen with PAL GC rgb cable: https://nfggames.com/forum2/index.php?topic=5090.msg35325#msg35325 XD

EDIT3:
Found some photos from the mod, which seem to have been lost from this thread:

Quote from: Shadow_Zero on July 06, 2020, 07:14:02 AMCan anyone comment on their experiences with this? I forgot to make a note myself (or can't find it anymore), but it seems that the SNES Jr RGB mod on the FRA N64 has the same issue as the early PAL SNES revision with the PAL GC rgb cables (220uf caps), and the screen being/turning black.

It has been many years since I looked into this, so this is all from memory...

If you have recreated the original video circuit for the French N64 (i.e added transistors onto the original Q1/Q2/Q3 pads) Then you have recreated the 'PAL specific' video circuit, which means you then need to use the PAL/French RGB cable which uses 75ohm resistors to ground on the RGB lines:-
http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm#snes

If you follow the NTSC circuit as per DarthCloud's schematic:-

You'll notice it mainly just requires 75ohm resistors in series on the RGB lines.

The BA6596F 'S-RGB A' video encoder chip is very similar to the later ROHM BH7236AF. An example circuit for the BH7236AF is shown on page 5 of this datasheet:-
https://www.mouser.co.uk/datasheet/2/348/rohm_semiconductor_rohms16460-1-1742560.pdf
Notice that the only components actually required for RGB output is a 75ohm resistor in series (In the console) and a 220uF capacitor (Usually in the cable)

If you follow the NTSC video circuit then you should end up with a mod that looks like this (Photo by kwyjibo):-

Then you can use a 'standard' NTSC RGB cable with 220uF capacitors on the RGB lines (The official PAL GameCube RGB SCART cable is similar in that it has 220uF capacitors on RGB, but it still has additional 'PAL specific' components on the Composite video line in both ends of the cable)

<EDIT>For the French N64 you should also either have a 75ohm resistor to ground on the Composite video line, or alternatively replace the R5 resistor on the French N64 motherboard with a 75ohm instead of the original 39ohm, then you should be able to use a straight passthrough Composite video cable like the NTSC models. Dont forget that RGB SCART typically still uses the Composite video signal for SYNC.

The photo is from topic starter kwyjibo: https://nfggames.com/forum2/index.php?topic=3083.msg21461#msg21461


I'll need to do some more reading, but my first thought is, what's the difference between the 1CHIP PAL SNES and the FRA N64 (with missing components mod, apparently called 'factory mod')?

Gamecube rgb cable works with 1CHIP PAL SNES, but it gets dark screen with the FRA N64 factory mod. Sorry if it's already explained in this topic, I'm not up to par yet  ^^;

You never got around to doing the mod yourself @Link83?

Quote from: DarthCloud on September 18, 2009, 07:53:46 PMLink, let me know how it look like if you mod a snes 2 using this!

EDIT:
Ah, got something, from your backlog 
https://nfggames.com/forum2/index.php?topic=3083.msg23629#msg23629

QuoteI am beginning to think that the little circuit on this French N64 was only there in order to maintain 'backward compatabilty' with the French SNES Scart cable.

https://nfggames.com/forum2/index.php?topic=3083.msg25880#msg25880

Quote from: undefinedSimply put, the originally planned video components for this French N64 were designed to work only with PAL SNES video cables  (Which use 75ohm resistors to ground) Its not the layout the 'S-RGB A' chips datasheet would have recommended, its what Nintendo had to do to maintain backwards compatibility with PAL video cables.

The NTSC method would be preferrable since it is the 'correct' method, its the layout the 'S-RGB A' chip was actually designed for, and is likely exactly what would have been recommended in the datasheet. It also means you could use 'standard' RGB cables with 220uF capacitors on R, G, B.

So now to figure out why the 'ntsc' method got me a black screen... Though it's long ago, maybe it was an other issue. Then again, Keropi on Assemblergames seems to have mentioned this issue as well:
https://www.assembler-games.com/threads/modding-a-pal-french-n64-for-rgb-also-what-cable-do-i-need.41394/page-2#post-609317

QuoteI just tried with the 75 ohms resistors in the 3 lines, I get a picture but it's dark. I am using a custom SCART cable that has 220mf caps in the RGB lines

EDIT2:
I'm kinda confused though, since all FRA N64 mods still seem to use your component list you mentioned here:
https://nfggames.com/forum2/index.php?topic=3083.msg23441#msg23441

QuoteQ1, Q2, Q3 = BQ14/2PB709AQ PNP Transistors
R42, R44, R46 = 75ohm Resistors
R41, R43, R45 = 39ohm Resistors
C11, C12, C13 = 47pf Capacitors

Or it's 'official' in regard that it 'was' intended, specifically for the French SNES RGB cable? And the NTSC 1CHIP SNES is the logic design (and works with both NTSC SNES/PAL GC and FRA SNES rgb cables)...?

Quote from: Shadow_Zero on July 07, 2020, 07:01:35 AMThe photo is from topic starter kwyjibo: https://nfggames.com/forum2/index.php?topic=3083.msg21461#msg21461

Ah, I knew I saved it from somewhere, thanks. I will update my post now

Quote from: Shadow_Zero on July 07, 2020, 07:01:35 AMI'll need to do some more reading, but my first thought is, what's the difference between the 1CHIP PAL SNES and the FRA N64 (with missing components mod, apparently called 'factory mod')?

The difference might be the Composite video line, which is used for sync with RGB.

NTSC Composite video cables are really simple - just a straight passthrough of the Composite video signal. However Nintendo really messed about with the video circuits in PAL consoles and created their own incompatible standards.

If I recall correctly (And this was more than a decade ago) the French N64 'NUS-CPU(R)-01' appears to be the only PAL N64 which has a 220uF (C15) capacitor on the Composite video line on the motherboard. This means it should just require a 75ohm resistor to ground inside the cable, like the PAL SNES.

In the other European N64's 'NUS-CPU(P)-01' they changed the video circuit, so they require a 75ohm resistor to ground inside the cable, and also preferably a 220uF capacitor as well. Nintendo actually has jumper positions on the European N64 motherboard for these two components, but deliberately left them off and put them inside the cable instead. Its a complete mess really, and I have no idea why they did it this way.

Quote from: Shadow_Zero on July 07, 2020, 07:01:35 AMGamecube rgb cable works with 1CHIP PAL SNES, but it gets dark screen with the FRA N64 factory mod. Sorry if it's already explained in this topic, I'm not up to par yet  ^^;

EDIT:
Ah, got something, from your backlog 
https://nfggames.com/forum2/index.php?topic=3083.msg25880#msg25880

Quote from: undefinedSimply put, the originally planned video components for this French N64 were designed to work only with PAL SNES video cables  (Which use 75ohm resistors to ground) Its not the layout the 'S-RGB A' chips datasheet would have recommended, its what Nintendo had to do to maintain backwards compatibility with PAL video cables.

So now to figure out why the 'ntsc' method got me a black screen (though it's long ago, maybe it was an other issue)

To maintain backward compatability with the PAL SNES/N64 Composite video signal, the official PAL GameCube RGB SCART cable also has a 75ohm resistor to ground hidden inside the 'MULTI OUT' plug, and a 220uF capacitor inside the SCART plug on a small PCB, all on the Composite video line.

If you have the correct 'factory mod' components, then really you should be using an official French SNES RGB cable, which has four 75ohm resistors to ground inside - one for each video signal (Red, Green, Blue and Composite video) There are no capacitors in the official French SNES RGB cable.

Quote from: Shadow_Zero on July 07, 2020, 07:01:35 AMEDIT:
I'm kinda confused though, since all FRA N64 mods still seem to use your component list you mentioned here:
https://nfggames.com/forum2/index.php?topic=3083.msg23441#msg23441

Quote from: undefinedQ1, Q2, Q3 = BQ14/2PB709AQ PNP Transistors
R42, R44, R46 = 75ohm Resistors
R41, R43, R45 = 39ohm Resistors
C11, C12, C13 = 47pf Capacitors

That post was simply my guess at the missing components, I never worked out if it was accurate, and it dates from a time when I was just beginning to understand how to mod consoles, so its really not some 'definitive guide' on how to restore RGB on French N64's. If any guides have used that post as a basis for a mod, then I would say that they are mistaken - I never posted it with the intention that someone would use it as an actual mod. I'm certainly no expert, I have just acquired knowledge by googling and reading, and I certainly wasn't as knowledgeable when I made that post/guess more than a decade ago.

Quote from: Shadow_Zero on July 07, 2020, 07:01:35 AMOr it's 'official' in regard that it 'was' intended, specifically for the French SNES RGB cable? And the NTSC 1CHIP SNES is the logic design (and works with both NTSC SNES/PAL GC and FRA SNES rgb cables)...?

In my opinion I would recommend ignoring the original PAL video circuit, and just use the NTSC video circuit as a guide since they more closely resemble the example circuits in the ROHM datasheets. In other words the NTSC design matches what the chip manufacturer intended.

The NTSC video circuit design allow you to use straight passthrough Composite video and S-Video cables, and only requires 220uF capacitors on RGB. The RGB capacitors were placed in the cable to save on console manufacturing costs, which makes sense when you consider how few people would have actually used the RGB output at the time.

On the other hand the PAL Nintendo video circuit designs are a complete mess and appear to have only been designed that way to try and region lock the video cables (Much like how they region locked PAL NES and PAL SNES controllers) It wasn't about saving on manufacturing costs as the PAL video circuit designs often required more components than the NTSC design on a number of board revisions (For example the PAL 1CHIP compared to the NTSC 1CHIP) Even the Composite video and S-Video signals require components in the PAL cables to make them work correctly. Nintendo kept messing about with the PAL 'MULTI OUT' standard, so each console generation requires slightly different components in the cable even though they all use the same 'MULTI OUT' port. For example:-

-The PAL SNES requires 75ohm resistors to ground on all five video signal lines (CVBS, Y/C, RGB)
-The European N64 requires a 75ohm resistor to ground and ideally a 220uF capacitor in series on Composite video. S-Video requires 75ohm resistors to ground plus a 220uF capacitor and a 68nF capacitor, and Nintendo never even released an official PAL S-Video cable.
-The French N64 only requires a 75ohm resistor to ground on Composite video, since there is already a 220uF capacitor on the motherboard.
-The PAL GameCube requires a 75ohm resistor to ground and 220uF capacitor in series on Composite video, and 220uF capacitors in series on RGB.

...This means the official cables for all these systems have slightly different compatibility issues with one another.

Nintendo even used to have a note on their European website about trying to identify which type of PAL Composite video cable you had by the colour of the 'MULTI OUT' plug (SNES/N64 is grey, GC is black) and explained that certain combinations may not work correctly or will make the picture too bright (Because the components inside are different)

Honestly once I realised what a mess Nintendo had made of PAL consoles, I replaced all mine with NTSC models and packed away all my PAL units. Even this was a pain, because Nintendo composite cables from both NTSC and PAL regions appear outwardly identical, so the only way to tell them apart without disassembly is by testing them with a multimeter to find out if they have a 75ohm resistor to ground inside the plug or not.

Anyway, thats just my opinion

Nice summary Link83!

I know you posted those missing FRA N64 components were a guess from your side, but it would seem using those makes the mod work anyway. Googling now on this mod I don't get a lot of hits, or they are in french pages (also saw a few youtube videos, but didn't see components details).

Ok, didn't think yet that the 75 ohm resistor on PAL composite could make a difference for RGB sync (although it's an educated guess at this point I think?). And good to know only the FRA N64 had both the 75ohm resistor and 220uF cap on the board.
Also found your 'discovery' back here:
https://nfggames.com/forum2/index.php?topic=3203.msg22338#msg22338
https://nfggames.com/forum2/index.php?topic=3203.msg23828#msg23828
;P

So to clarify my FRA N64 experiences:
- vdc chip mod + ths7314 booster works with every RGB cable I throw at it
- missing components ('factory') mod results in dark screen
- s-rgb ('snes jr') mod results in dark screen

That last one is odd to me, because it works fine on a 1CHIP PAL SNES.
I have used both the official GC RGB cable as various third party cables. I don't know if third party cables also did the 75ohm resistor on composite in the multi a/v plug (I kinda would guess 'not').


In general, region locking video cables just sounds so... meh. Also, it's only the case really for RGB cables. You don't get a dark screen when using NTSC composite or s-video on a PAL console (if you get the proper color is another matter perhaps). What were they thinking??!


I forgot if I already read this or not, but what's the difference between the PAL 1CHIP and the NTSC 1CHIP SNES, concerning RGB output circuitry? (eviltim has the cable schematics: http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm#snes )
As mentioned in https://nfggames.com/forum2/index.php?topic=3083.msg46382#msg46382, NTSC 1CHIP is only S-RGB pinout -> 75ohm resistor -> output

EDIT:
Oh wow, google got me to an extensive schematic of the PAL SNES 1CHIP: https://videogameperfection.com/forums/topic/schematic-for-1chip-pal-snes/
I wonder if it's accurate, it seems to mention a 100ohm resistor to ground, a 39ohm resistor and a C2412 transistor.

Also found a nice wiki: https://console5.com/wiki/SNES !

Do you have any photos of the mod installed on your French N64? Without knowing exactly what type of modification has been performed its hard for me to determine what the problem is.

Unfortunately, I don't think I made photos back then. I'll try to have a look around if I can find anything.
I did the SNES jr mod as described on GamesX: https://gamesx.com/wiki/doku.php?id=av:snes2rgb

Using the PAL SNES RGB cable (75ohm resistors, no caps) it worked fine, using the PAL GameCube RGB cable (220uF caps) the screen turned dark, just like with the first revision SNES. Because of that, I remodded it using the VDC chip plus THS7314 booster, then the PAL GameCube RGB cable worked as well.


The pre-modded N64 I got from a gameshop in France (eBay) is gued and I can't check for the details, but I assume it used this mod:

but you confirmed it's to be expected with adding all the missing components that the screen will turn dark with a PAL GameCube RGB/220uF caps cable.

I think I've got 1 FRA N64 left that needs modding (still need to open it), so I can give the 'SNES jr. mod' another go.

But like said, I didn't take composite video resistor/cap, for sync, into account (but could that lead to a screen turning dark??).


EDIT:
Ah, found out I actually did not have a FRA N64 left, so can't try some tests with the S-RGB mod. Tried to look for another one on eBay, but that seems to be a more difficult (or pricier) endeavour than 5-10 years ago