Official Nintendo AV Cables for SNES, N64 and Gamecube - resistors & capacitors?

[Shadow_Zero]

Very interesting topic to read. The quest of Link83 for the truth! 

I'll probably be opening my SNES', N64's and RGB cables this year. If there are any specific things I can look out for, just let me know!


PS: Can't we have a 'bookmark' option in the forum? 

[Shadow_Zero]

Here's an image of my Gamecube RGB cable by Speedlink:




It's got 3x 220uF caps and resistors from pin 2 to 4 and pin 6 to 4. Can someone explain me that? (it's the only Nintendo scart cable I have with this construction).

[Shadow_Zero]

Also, for anyone who may be interested in opening their Official Nintendo Scart Cables I took this picture and added some notes on how best to do it (The notes are abit small I know, but if you save the picture and then open it you can zoom in and read the text  ):-

I saw an instruction somewhere with screenshots. Not sure if it was this one, but I'm looking for it now (struggling to open the official Gamecube RGB cable).

EDIT:
Ah, it was a guide from MMMonkey: http://www.mmmonkey.co.uk/official-pal-gamecube-rgb-cable-on-ntsc-consoles/

[Fix_Metal]

Don't know if anyone replied to this earlier, but...

I managed to find my Official PAL Nintendo Composite cable and there appears to be more than just a resistor - there is also a 220uf capacitor aswell - anyone care to explain whats going on!

Same as what you'd need to output composite from Sony CXA encoder in SMS2 mod.
That gives you some filtering (can't Bode it atm) and DC decoupling.

Can anybody tell me what value resistor it uses? I guess its 180ohm. I have tried to work it out by the color banding but am not very good at it!

That's for RGB switching. +5V is going to #16, while +5V in series with the 180Ohm goes to the #8.

[Shadow_Zero]

I just wanted to update that I tested both a PAL SNES/N64 Composite cable and a PAL Gamecube Composite cable on a PAL N64 console.

Visually I couldnt see any difference using either cable (but maybe im not looking hard enough)

I then decided to measure the DC offset from the PAL N64. Using the PAL Gamecube Composite cable (75ohm resistor to ground and 220uF capacitor in series) it measured 0.00V as I expected.

Next I tried the PAL SNES/N64 Composite cable (75ohm resistor to ground) and somewhat surprisingly got readings betweens 0.7V and 1.35V DC - varying according to how bright the game picture was. During gameplay it seemed to average out at about 1V DC.

I am not sure what effect this DC offset would have on the picture quality, but I dont think it would be for the better. I have read in many audiophile forums that having a DC offset on headphone amplifiers higher than 20mV (0.02V!) can have a detrimental affect on the sound and can damage the speakers , so I assume a 1V DC offset on Composite video would be the same/similar(?)

All this suggests that to me their definitely should be a 220uF capacitor in series on the PAL N64 Composite line aswell as the 75ohm resistor to ground, and that Nintendo just cheaped out on making the PAL N64 Composite cable because they could get away with it

I havent been able to test the PAL SNES yet as I have just accidentally blown the fuse on my console (Even though I 'discharged' it for 10 seconds first) but when I get a new fuse I will compare the PAL SNES aswell and update this thread.

Sorry if anyone finds this info boring - I realise it wont interest many as its only Composite Video!

I recently added the capacitor on my Composite cable but it stopped working.  When i remove the capacitor the cable works again.

What's the theory on the fact that adding the capacitors on the composite cable makes it stop working? (while they should be there)

[Shadow_Zero]

Also I thought it might be good to point out that prior to recieving this Official SNES Scart cable, I had been using an Official Gamecube Scart cable on my SNES with no problems whatsoever. It could just be because my TV is able to handle the signal levels better than other peoples (which often show no picture or fades to black after a few seconds)

Alternatively could it be there is a difference on the video lines of my PAL SNES? It is the very last revision made in 1995, with the code SNSP-CPU-1CHIP-01 printed on the motherboard. Heres some pictures of my SNES which also show the video lines:-

Was it so that the PAL 1-chip SNES supports the Gamecube cables? (edit: yes it does!)
If I use the official GC RGB cable with my (early revision) SNES it turns dark, as expected I would say.


EDIT:
Guess this answers that (unless I interpretet it wrongly)

Regarding the RGB output circuit of the PAL SNES - I've just pulled apart one of mine (1992 model) and had a look at the board. Like MKL said, there's only two 30 ohm resistors there! Something's not right. I'll trace it out again...

Maybe Nintendo revised their video output circuit in later models. You put a cap in series with the video from the 1992 PAL SNES and nothing will come out.

I examined the internals of my 1992 PAL SNES and can confirm the presence of a 30 ohm resistor in series with red, green, and blue. The circuit looks like:
If you put a capacitor in series with the signal it won't work. Nintendo must have changed the circuit somewhere between 1992 and 1995. I presume that their official cable works perfectly with both versions.

EDIT:
Additionally, what would the effect be if the 75ohm resistor was not on the composite line (and only on R, G, B)?

[Shadow_Zero]

So it is different to the PAL Gamecube Composite cable as that had a little circuit board with a 220uF capacitor in series aswell as the 75ohm resistor to ground (See first page of this thread for pics)

Link83 (or anyone else), you still got the Gamecube composite pics somewhere? (images in the first post are dead)
Found this one:


Also I'm wondering. We say there should be a 220uF capacitor in series on the PAL N64 Composite line aswell as the 75ohm resistor to ground, and that Nintendo just cheaped out on adding the cap in the the PAL N64 Composite cable because they could get away with it. The 220uF cap with the GC RGB cable results in a black picture with the SNES (and FRA S-RGB modded N64 via missing components). A composite cable with 220uF cap would not?

Is it also official that a GC RGB cable does in fact work with a PAL 1-CHIP SNES? <-- yup, works!

[unshe]

About Gamecube cable and PAL 1-chip snes, YES it is working perfect. Tested on PAL 1-chip-01 and Pal 1-Chip-02.

[Shadow_Zero]

Nice.

Today I tested with (official) composite on my Sony Bravia LCD, which makes a BIG difference compared to my JVC 50hz CRT. The PAL launch N64 shows A LOT of dot crawling, while the NTSC N64 doesn't have this issue (just the unsharp edges you have with composite). So that was kinda new to me, since I'm used that composite video always has dot crawling.

Other than that, I don't see any difference between the PAL SNES composite cable and the PAL GC composite cable in video quality on the N64, just like @Link83  concluded.

[Shadow_Zero]

Unfortunately not much activity here 
Trying to pick up my N64 mod projects again (after buying a house, getting married and becoming a dad O_o ).
Still no activity from Link83 around here?

[Shadow_Zero]

I just wanted to update that I tested both a PAL SNES/N64 Composite cable and a PAL Gamecube Composite cable on a PAL N64 console.

Visually I couldnt see any difference using either cable (but maybe im not looking hard enough)

I then decided to measure the DC offset from the PAL N64. Using the PAL Gamecube Composite cable (75ohm resistor to ground and 220uF capacitor in series) it measured 0.00V as I expected.

Next I tried the PAL SNES/N64 Composite cable (75ohm resistor to ground) and somewhat surprisingly got readings betweens 0.7V and 1.35V DC - varying according to how bright the game picture was. During gameplay it seemed to average out at about 1V DC.

I am not sure what effect this DC offset would have on the picture quality, but I dont think it would be for the better. I have read in many audiophile forums that having a DC offset on headphone amplifiers higher than 20mV (0.02V!) can have a detrimental affect on the sound and can damage the speakers , so I assume a 1V DC offset on Composite video would be the same/similar(?)

All this suggests that to me their definitely should be a 220uF capacitor in series on the PAL N64 Composite line aswell as the 75ohm resistor to ground, and that Nintendo just cheaped out on making the PAL N64 Composite cable because they could get away with it

I havent been able to test the PAL SNES yet as I have just accidentally blown the fuse on my console (Even though I 'discharged' it for 10 seconds first) but when I get a new fuse I will compare the PAL SNES aswell and update this thread.

Sorry if anyone finds this info boring - I realise it wont interest many as its only Composite Video!

Following up on @Link83's post in an other topic, it's interesting to debate (and test) if the missing 220uF cap on composite video could result in sync issues (which could also impact RGB, if not using csync).
Unless I'm totally talking/thinking gibberish now! At least I'll try some tests with my RGB modded FRA N64's, since I had various results in video output...


EDIT:
Found an interesting quote from @unshe:
https://nfggames.com/forum2/index.php?topic=37.msg34189#msg34189

ABout resistors/caps on CVBS.. it is used only for Sync, so if the sync signal is still "good for the tv" it will work. So resistors or caps on CVBS are not so important...