Author Topic: Official Nintendo AV Cables for SNES, N64 and Gamecube - resistors & capacitors?  (Read 99612 times)

Online Link83

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Hi everyone,

I hope this is ok to ask here - I have searched the GamesX site but couldnt find all the info I was looking for.

I am trying to find pictures/information about the the internal wiring of all the Official Nintendo AV cables for both the NTSC and PAL SNES, N64 and Gamecube consoles

I am just curious to know what resistors and capacitors Nintendo 'officially' used in their cables, and how they were wired up.

I believe all the Composite AV cables and S-Video cables are the same for each region, is this correct?

Im am quite new to modding so please forgive me if I have stuff wrong, or am asking obvious questions.

COMPOSITE AV CABLES

As I understand it the only difference is that PAL composite AV cables have a resistor between video and ground inside the console end of the cable, whereas the NTSC versions do not. I have read 75 ohms is the value to use, but am curious to know if this is what the official nintendo cable uses/has inside?

UPDATE:-
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!
Heres an official NTSC GC Composite cable:-


and heres the PAL GC Composite cable:-



would love to know exactly how they differ/what the capacitor and resistor are for.

I havent checked to see if my PAL SNES/N64 Composite cable is different again but I will dig it out soon.

S-VIDEO CABLES

In all my searches I have never come across an official PAL S-Video cable - was one ever made? and if so does anyone have any pictures of it, and the insides?

I have read that to make a PAL S-video cable you need to add resistor(s) to an NTSC S-video cable, but have read conflicting advise that you either need to 1)Connect one 75ohm resistor between luma and ground, or 2)Put 75ohm resistors on both the luma and ground lines (not between them)

Which is right?

RGB SCART CABLES
Also, when it comes to the official RGB Scart cable things seem to get quite abit more confusing. There are two official RGB scart cables that I know of - one for the PAL Gamecube, and one for the Japanese Super Famicom. Theres rumours that there was an official RGB Scart lead for the PAL SNES but I have never seen it.

The PAL Gamecube scart cable has four 220uf capacitors and one resistor. There is a capacitor on red, green and blue, but am not sure what the last one connects to? Heres a pic of the resistor:-


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!

I have found a schematic here:-
http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm#gamecube
but it doesnt seem to match the layout of the official RGB cable:-

Is shows an extra wire and 75ohm resistor to pin 18, when there is none on the official cable, and it also has no wire to pin 17 where there is one on the official cable!

Also, I know the PAL SNES doesnt need the red, green and blue capacitors, but does it still need the last capacitor and the resistor?

and what about the NTSC N64 when RGB modded - does that need any capacitors or resistors or not?

Lastly, I have read that when building a PAL SNES RGB Scart cable, once the capacitors are removed the image can be too bright. Some people add resistors to the red, green and blue lines, but what value is correct to use? I have read of people using 30ohm, 33ohm and 47ohm resistors and some using none at all! Who is right? What makes the brighness level perfect/normal?


Lastly, out of curiousity does anybody know how the RGBJ Scart cable for the Super Famicom was wired up? Or does anyone have pictures of its internals? For those that have never heard of it heres a picture of what it looks like:-

(It is still available from the site whos photo it is tagged from)

I imagine inside it would look similar to the PAL Gamecube RGB Scart cable but it would be intererested to know for sure.

Many thanks in advance  ;D
« Last Edit: July 15, 2008, 10:47:06 AM by Link83 »

Offline l_oliveira

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I think the cable is the same but the pinout on the 21 pin connector is different from SCART.

Offline Codeman

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I would also like to know more about these RGB cables for Nintendo systems, I already asked in my previsou thread about a Dragon Cable but got no reply

ill ask again

I assume a PAL GC would need all the caps on the RGB pins, correct?

a PAL SNES doesnt need the RGB caps, correct?

the 4th capacitor you mentioned is connected to the Composite/Sync pin, correct?

assuming I have a RGB modded N64, which cable should I user? A SNES cable without caps or a GC cable with caps?



Offline albino_vulpix

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I would also like to know more about these RGB cables for Nintendo systems, I already asked in my previsou thread about a Dragon Cable but got no reply

ill ask again

I assume a PAL GC would need all the caps on the RGB pins, correct?
Correct

a PAL SNES doesnt need the RGB caps, correct?
Correct

the 4th capacitor you mentioned is connected to the Composite/Sync pin, correct?
Yes, the scart cables have the resistor and capacitor on the composite video signal, just like in the PAL AV cables.

assuming I have a RGB modded N64, which cable should I user? A SNES cable without caps or a GC cable with caps?
Use a cable with the caps.



Offline phreak97

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i've tried asking about this stuff before, we should add the known configurations to the wiki then build up from there.

Offline Codeman

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Awesome, thanks for the reply!

I think ill mod my Dragon Cable then! Ill throw a 3-way on/off switch for those capacitors and make it a universal Nintendo cable ^^

Offline albino_vulpix

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On a slightly related topic, can the pins of a snes/64/cube cable be taken out and repositioned?

Offline phreak97

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yes, but i seem to remember it wasnt that easy, and you need to sacrifice a cable or two to get enough pins for an rgb cable. assuming thats what youre after.

Offline Alcahest

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Here are pictures of the official Nintento RGBJ cable for Super Famicom, SHVC-010
Scart plug side:
http://videoff7.free.fr/shvc010-plug.jpg

another one (sorry for the quality, taken from a jpn site)
http://videoff7.free.fr/shvc010-plug2.jpg

I wish i knew more about the internals of this cable too (capacitor used etc..)
Later,

Alcahest
« Last Edit: July 14, 2008, 08:46:56 AM by Alcahest »

Offline NFG

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These cables are very easy to open.  There's a twist-off cap where the connector meets the cable, and you need only compress the four little tabs (push them in towards the cable) and twist the cap one or two rotations, and it will come off, allowing the shell to open.

Offline Alcahest

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Yep, I learned that the hard way by opening the official Euro Gamecube RGB cable I received a few days ago.
If anyone has the japanese official SHVC-010 JRGB cable, don't hesitate to post pics!
I am only interested in seeing if RGB sync is taken from Pin3 CSYNC or Pin9 CVBS on the SFC side.
And also if this wire is connected to any resistance/capacitor before reaching the scart end.
I don't really want to spend another 50US$ at ncsx just for this info ^^;
Thanks,

Alcahest

Offline RGB32E

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I have two (maybe even three) of the SHVC-010 cables.  I didn't check to see where the Euro gamecube RGB cable got it's sync from... since it just "works" on my PVM-2030 with either (CVBS or CSYNC).  But that might explain why connecting the snes with that cable to the Panny plasma's PC input didn't work.... (unless it truly didn't accept CSYNC to begin with).  My first SNES JRGB cable is currently tansformed into a short Scart cable with two female RCAs for auto.... for use with my RGBS to Component converter.  I'll post the answer to the question at hand later tonight....  :-X

Online Link83

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Wow, surprised to see this thread back up!  :o

I have two (maybe even three) of the SHVC-010 cables.  I didn't check to see where the Euro gamecube RGB cable got it's sync from... since it just "works" on my PVM-2030 with either (CVBS or CSYNC).  But that might explain why connecting the snes with that cable to the Panny plasma's PC input didn't work.... (unless it truly didn't accept CSYNC to begin with).  My first SNES JRGB cable is currently tansformed into a short Scart cable with two female RCAs for auto.... for use with my RGBS to Component converter.  I'll post the answer to the question at hand later tonight....  :-X
I would love to see some pictures of the internals of an unmodified SHVC-10 cable if you can?

-------------------------------------------------------------------------------------------------------------------------------------

Also, to anyone who may be interested, I managed to acquire an Official European SNES Scart cable. It seems they are quite rare - as they were only released in France AFAIK. Heres a pic of one new in the packaging, and the one I recieved:-


As you can see, it has a grey Scart plug like the Japanese SHVC-10, rather than a black scart plug like the Official Gamecube Scart cable.

Heres pictures from inside the Scart plug:-


Heres some of the circuit board disconnected:-


and heres the wiring to the Multi AV plug:-


It has a small circuit board with four components. One is obviously a 100 ohm resistor, however I have no idea what the other three are? (Not seen anything like them before)
They have codes on them which are as follows:-

A124TA F

C124TF F

RS4750J

Googling them came back with nothing  :(

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 really think it would be good if someone could add circuit diagrams to the Wiki for all the Official Scart cables out there. I would do it myself but im not that knowledgable on how circuits work (In case you hadnt guessed!) but I would be happy to provide as many pictures of the insides of Official Scart cables as anyone wants.

I know this page is fantastic:-

http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm

and im sure they all work great, but they dont have exactly the same circuits or components as the Official Scart Cables use (As Alcahest noticed in his other thread)
« Last Edit: July 15, 2008, 10:55:52 AM by Link83 »

Offline RGB32E

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Well.... I took a look at one of my unmodified SHVC-10 cable and the two ends of the modified one (is a JRGB).... looks like nintendo didn't wire the official JRGB cables to use CSYNC, they use CBVS!  Inside the 21 pin connector, RGB are filtered with 220uf caps, composite video is fed to the CSYNC pin, +5VDC is fed through series 75 ohm resistor to the +5VDC pin (see gamesx JRGB pinout).  GND and audio is fed to the appropriate pins.  I don't have a camera to take pictures, but will try to in the near future.

Offline NFG

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It's actually more common to use Cvid than Csync in an RGB cable, so what you found isn't unusual.

Offline Alcahest

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Link83, great thread indeed.  8)
Interesting pics of the PAL SNES official RGB cable.. i wonder indeed what those components are, they're prolly just "housing" 47 ohms resistors for R,G,B & composite pins?

Well.... I took a look at one of my unmodified SHVC-10 cable and the two ends of the modified one (is a JRGB).... looks like nintendo didn't wire the official JRGB cables to use CSYNC, they use CBVS!  Inside the 21 pin connector, RGB are filtered with 220uf caps, composite video is fed to the CSYNC pin, +5VDC is fed through series 75 ohm resistor to the +5VDC pin (see gamesx JRGB pinout).  GND and audio is fed to the appropriate pins.  I don't have a camera to take pictures, but will try to in the near future.

Excellent RGB32E, so you confirm that SFC CVBS is not modified in any way before it reaches the TV.. very good to know for my problem ^^ At last i can totally rule out a problem of the cable as even the official Super Famicom one doesn't alter CVBS in any way. (i'm using the official PAL GC RGB cable, seems exactly the same as SHVC-010 after all.)
See you,

Alcahest

Offline viletim

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Link83,

My SCART cable diagrams sometimes differ from what's inside the official cable. It's mainly because I have very few official SCART cables and have to rely on (often non-technical) contributiors and guess work.

I'd like to draw up a circuit diagram of your cable but I need some more information....first do you own a multimeter (and know how to use it)?

BTW:
A124TA F = PNP transistor
C124TF F = NPN transistor
RS4750J = resistor network with 5% tolerance, the value is a bit ambiguous but probably 47 ohms

Online Link83

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Link83,

My SCART cable diagrams sometimes differ from what's inside the official cable. It's mainly because I have very few official SCART cables and have to rely on (often non-technical) contributiors and guess work.
Hi!
I hope you dont think I was criticizing you in any way - You have done fantastic work drawing up all those diagrams. I just think it might be useful to have circuit diagrams of the official scart cables aswell if possible :)

I'd like to draw up a circuit diagram of your cable but I need some more information....first do you own a multimeter (and know how to use it)?

BTW:
A124TA F = PNP transistor
C124TF F = NPN transistor
RS4750J = resistor network with 5% tolerance, the value is a bit ambiguous but probably 47 ohms

Ah thats interesting - do you think there is any way for us to work out the values of the transistors?

I have a digital multimeter and know roughly how to use it - im no expert though, but if you tell me what settings to place the dial on and where to put the probes I can gladly tell you the read out.

Although if you'd like I would gladly send the scart cable to you and you could draw up the circuit diagram and send it back whenever you have finished with it?

I have quite a few official scart cables aswell if your interested, heres a list:-
Official SNES Scart cable
Official Gamecube Scart cable
Official Dreamcast Scart cable
Official Xbox Scart cable
...and am hoping to acquire an Official Mega Drive 2 Scart cable aswell
« Last Edit: July 16, 2008, 01:12:09 AM by Link83 »

Offline RGB32E

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It's actually more common to use Cvid than Csync in an RGB cable, so what you found isn't unusual.

It's a surprise to me!  :o  I just checked out the official gamecube scart cable that I reterminated for the PVM DB25 and found that it carries both composite (filtered by a 220uf cap) and CSYNC over the cable.  Hence, its the modders choice to use either!  So, looks like I'll be making a minor change in my cable (remove filtered composite and replacing with CSYNC on the DB25F connector).  R, G, B, and composite are filtered with 220uf caps (as pictured by Link) on the PCB.  CSYNC is just routed from one header on the PCB to another (with wire ready for soldering)....

I forgot about this.... even though it isn't necessarily applicable to the SFC, but makes sence in case PAL snes is used with Japanese 21 pin RGB cable:

"A PAL SNES outputs +12v on pin 3, not composite sync. This is for a SCART TV to automatically detect RGB input."
« Last Edit: July 16, 2008, 02:36:25 AM by RGB32E »

Offline RGB32E

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(i'm using the official PAL GC RGB cable, seems exactly the same as SHVC-010 after all.)

The PAL GC RGB and SHVC-010 are not quite the same... Since you are using the official GCN SCART cable, you have the choice of using filtered composite or composite sync (both are fed through the scart plug PCB).  Which signal are you using as sync?  Either choice of sync (filtered CVBS or CSYNC) will work fine on a Sony PVM, but not necessarily on other monitors or RGBS accepting devices.

Some similarities between official SFC RGB and official GCN SCART cables:
-R, G, and B are filtered with 220uf caps
-CVBS is fed through the cable

Differences:
-Both CVBS and CSYNC (or +12VDC for PAL systems) are fed through the GCN cable (only CVBS is wired/used on SFC RGB cable)
-CVBS is filtered with a 220uf cap on the GCN cable (CVBS is not filtered on SFC RGB cable)
-GCN cable uses 100 ohm resistor for the SCART mode setting and the SFC connects VDC through series 75 ohm resistor to the +5VDC pin of 21 pin connector.

I hope this helps....  ???
« Last Edit: July 16, 2008, 02:38:19 AM by RGB32E »

Offline Alcahest

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The PAL GC RGB and SHVC-010 are not quite the same... Since you are using the official GCN SCART cable, you have the choice of using filtered composite or composite sync (both are fed through the scart plug PCB).  Which signal are you using as sync?

I've tried both and even Chroma, separately, together, i tried everything  ;D
Flaw is there on all of them. Flaw is there with composite regardless if it is filtered or not too.

Quote
Either choice of sync (filtered CVBS or CSYNC) will work fine on a Sony PVM, but not necessarily on other monitors or RGBS accepting devices.

Some similarities between official SFC RGB and official GCN SCART cables:
-R, G, and B are filtered with 220uf caps
-CVBS is fed through the cable

Differences:
-Both CVBS and CSYNC (or +12VDC for PAL systems) are fed through the GCN cable (only CVBS is wired/used on SFC RGB cable)
-CVBS is filtered with a 220uf cap on the GCN cable (CVBS is not filtered on SFC RGB cable)
-GCN cable uses 100 ohm resistor for the SCART mode setting and the SFC connects VDC through series 75 ohm resistor to the +5VDC pin of 21 pin connector.

I hope this helps....  ???

Yes majorly  ;D
It proves 100% that what I experience is not a cable issue.
Thanks for all those details. Pretty much all is known about SNES/SFC cables now :D
See you,

Alcahest

Offline viletim

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Link83,

Here's what needs to be done for the SNES SCART cable:

1) Set your multimeter to continuity test (beeps when you touch the probes together) and find out which pins of the scart socket connect to which pins of the PCB.
2) Measure the resistors - the resistor network is four resistors connected inside a signle package. They all have one leg connected together which is marked with a dot. So measuring the resistance between the dot leg and any other leg should give the correct value.
3) Work out the pinout of the transistors. This is a bit tricky... First set the meter to diode test mode (in some cheap meters diode test and continuity mode are the same). The NPN transistor looks like two diodes with their cathodes connected. Place the red probe on any pin and the black probe on another, is there a reading on the display (500-700mV drop usualy)? If so then place the black probe on the other leg and check if it too has a forward voltage drop. If not, then move the red probe to another pin and repeat. If both pins do then the pin the red probe is on is the BASE, the one with the highest voltage drop (it may only be a few milivolts higher) is the EMITTER, and the other is the COLLECTOR. The PNP transistor works the same way except the red and black probes are exchanged.

RGB32E,
The series capacitor sometimes found in SCART cables is not part of a filter. There is no (intential) filtering going on, its purpose is just to pass the AC signal withough disturbing the DC level. Its a coupling capacitor and the signal is coupled through the capacitor.

And why would you be surprised that composite video (CVBS) is normal connected to the composite video out pin of the SCART plug??? It's a video input, not a digital sync input. The two are not the same electricaly. Sort of, but not quite, like the difference between the signal output of a CD player and a power amplifier. Both signals carry the same information but are meant for different purposes.

Offline RGB32E

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Its a coupling capacitor and the signal is coupled through the capacitor.
Sure.... works for me... so why were you using 180 ohm resistors again in your cables?

And why would you be surprised that composite video (CVBS) is normal connected to the composite video out pin of the SCART plug??? It's a video input, not a digital sync input.
I don't believe I typed anything like that... read what I wrote again.  I was surprised that the "Official" Japanese SFC RGB cable does not use pin 3 (CSYNC/+12VDC on the snes multi-av connector) for obtaining the sync (uses composite video instead of CSYNC).  I'm sorry you didn't understand that...  :'(

Offline Alcahest

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viletim, do you have any idea what a PNP transistor and a NPN transistor are doing in the EURO SNES RGB cable?  :o
Is it possible that the JRGB input on JPN TVs and RGB input on EURO TVs are not exactly similar when it comes to their expected incoming signals? (voltage levels..)

RGB32E, isn't it just a matter of falling back to composite if tv can't process RGB? (for the sake of Japanese tv retrocompatibility), like we have in europe?

Offline RGB32E

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RGB32E, isn't it just a matter of falling back to composite if tv can't process RGB? (for the sake of Japanese tv retrocompatibility), like we have in europe?

Yeah... that's completely plausible...  :-\  I've seen it happen on a RCA brand television (NTSC) that had a euroconnector (SCART) on it.  When feeding RGBcvS to it, it fell back to composite... and I decided to give the TV away to a friend in need...  ;)  I haven't seen encountered it on a JRGB TV... but I wouldn't be surprised about that. :P  Man... SCART is a pain!

Online Link83

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Well I think i found the 'dot' point, if it is the dot on the left in this picture:-

I measured the resistance between that 'dot' point (Which is connected to gound) and the other four points (R, G, B, and Composite). I was expecting it to say 47 ohms (especially since the RS4750J code printed on it has a '47' in it) but it in fact said 75 ohms! (Perhaps the code actually meant 4x75ohm resistors?)

So does that mean there should be 75 ohms resistors on the R, G, B, and Composite lines of a PAL SNES Scart cable, or does it make a difference that its a resistor network (not individual resistors) with one leg connected to ground?

Heres some closer pictures of the two transistors showing the codes:-


I was trying to work out which was the base, emitter and collector for each transistor and drew up this diagram with paint on the circuit board:-


It looks like the two transistors are only connected to +12v, +5v and Ground - so perhaps they are only important for scart auto-switching. I dont undertand why these transistors are necessary though?

I would still be happy to make any readings I can if you could tell me/mark which points are the base, collector and emitter?

Also, if  it helps at all here is a picture of my Digital MultiMeter:-

According to the instructions it has a setting specifically for transistors called 'hFE' - no idea how to use it though or if it would help!
« Last Edit: July 20, 2008, 04:18:31 AM by Link83 »

Offline viletim

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Link83,

That diagram is really helpful!

Ok, 4*75 ohm resistors, that sounds more like Nintendo... These transistors are "digital", meaning that they have one or more resistors inside. Full part numbers would be DTA124TA and DTC124TF. I've got the datasheet, drawn a circuit. It's actual purpose has me completely befuddled though...

I need some active measurements. Plug everything in (cable, nintendo, TV), switch it all on and measure the voltage (with respect to ground) on:
1) the +12v line coming from the SNES (lets see what it really is)
2) pin 8 of the SCART connector
3) pin 16 of the SCART connector

And a couple of passive ones:
Then switch everything off and measure the resistance between pin 8 of the SCART connector and ground (this is actually a measurement of your TV). Now disconnect the cable from everything and measure the resistance between the +12v line coming from the SNES and pin 8 of SCART.

Offline MKL

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My SCART cable diagrams sometimes differ from what's inside the official cable. It's mainly because I have very few official SCART cables and have to rely on (often non-technical) contributiors and guess work.

So where did you get the idea that the RGB lines needed a 47ohm resistance? I never noticed an overly bright picture without any resistance (and in any case 47ohm wouldn't be enough to make a really noticeable difference) and the official cable now confirms no resistors should be put in the RGB lines. The 75ohm resistors to ground have a parallel with the CVBS one which makes sense.

Offline viletim

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My SCART cable diagrams sometimes differ from what's inside the official cable. It's mainly because I have very few official SCART cables and have to rely on (often non-technical) contributiors and guess work.

So where did you get the idea that the RGB lines needed a 47ohm resistance? I never noticed an overly bright picture without any resistance (and in any case 47ohm wouldn't be enough to make a really noticeable difference) and the official cable now confirms no resistors should be put in the RGB lines. The 75ohm resistors to ground have a parallel with the CVBS one which makes sense.

Code: [Select]
Va = 1.4Vpp (measured)
Vb should be 0.7Vpp (video standard)

R1 is inside all PAL Super Nintendos
R3 is inside all SCART TVs

What Nintendo did: 
Va--[R1]--+---------+--- Vb
     30   |         |
         [R2]      [R3]
          |75       |75
          +---------+--- Ground
Vb = 1.4 / (30 + 75//75) * 75//75 = 0.77Vpp

What I did: 
Va--[R1]----[R2]----+--- Vb
     30      47     |
                   [R3]
                    |75
                    +--- Ground
Vb = 1.4 / (30 + 47 + 75) * 75 = 0.69Vpp

What you advocate:
Va--[R1]------------+--- Vb
     30             |
                   [R3]
                    |75
                    +--- Ground
Vb = 1.4 / (30 + 75) * 75 = 1.00Vpp

Offline MKL

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Thanks. I've never spent too much time to figure out the SNES video output circuitry due to traces being hard to follow (internal and hidden by the external ground plane) but I took a quick look inside a PAL SNES I had around and could only see two 30ohm resistors instead of three. Do you have full schematics of the video circuit?

Online Link83

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Link83,

That diagram is really helpful!
Thanks!  ;D I did one for the Gamecube Scart cable aswell if your interested:-

(I have also slightly re-done the SNES one in my previous post)
In case anybody is wondering - the colours I used in the diagrams are based on the colours of the actual wires used in the cable - not always related to what the signals are. Also, they dont show the audio wires as they just connect directly to the scart plug.

Ok, 4*75 ohm resistors, that sounds more like Nintendo... These transistors are "digital", meaning that they have one or more resistors inside. Full part numbers would be DTA124TA and DTC124TF. I've got the datasheet, drawn a circuit. It's actual purpose has me completely befuddled though...
Same here  ??? - they are not used on the Gamecube Scart cable either -  the only similarity is 100ohm resistor present on the +5v line.

if I wanted to re-create the Official PAL SNES scart cable, could I do it on a third-party Gamecube cable by removing the capacitors and putting 75 ohm resistors in there place? - or do the resistors have to be connected to ground/be a resistor network?

I need some active measurements. Plug everything in (cable, nintendo, TV), switch it all on and measure the voltage (with respect to ground) on:
1) the +12v line coming from the SNES (lets see what it really is)
2) pin 8 of the SCART connector
3) pin 16 of the SCART connector

I take it you mean connect it all up with the Scart plugs cover removed and plugged into the TV? (So that I can still make contact with the pins for the readings?) If so I would love to do this but I cant at present as my TV is a 28 inch CRT and I cant get round the back of it very easily in order to connect the probes to the pins :( I have also got a portable CRT TV in the attic though which I will get down as soon as I can and do those tests for you though.

I did do some tests though without the SNES being connected to the TV. My PAL SNES outputs 12.12v on Pin 3 and 5.01v on pin 10 (When using Pin 6&7 for the ground)

Also, when connected to the Scart cable Pin 8 reads +12.14v, and Pin 16 reads 4.99v (With Pin 17 used as ground) I dont know if these readings are of any use to you?

And a couple of passive ones:
Then switch everything off and measure the resistance between pin 8 of the SCART connector and ground (this is actually a measurement of your TV). Now disconnect the cable from everything and measure the resistance between the +12v line coming from the SNES and pin 8 of SCART.
I couldnt do the first of these tests unfortunately, but did try the second one with the cable disconnected from everything. I connected the probes between the +12v line (Pin 3) and Scart Pin 8 and got no reading at all. I tried it on every setting for resistance and there was definitely no measurement (Said '1' on the screen, just like when the probes are not connected to anything)

I even tried measuring resistance on the cable between all of these these points:-
+12v (Pin 3) to Scart Pin 8 - nothing
+12v (Pin 3) to Scart Pin 16 - nothing
+5v (Pin 10) to Scart Pin 8 - nothing
+5v (Pin 10) to Scart Pin 16 - 101 ohms - obviously due to the 100 ohm resistor on the circuit board.

Any other tests you would like me to try without connecting to the TV?

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:-



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On a somewhat unrelated note:-

I am curious to know how you are able to measure the voltage of the video lines to make sure they are 0.7vpp? Could I do this with a normal digital multimeter?

Also Viletim, since there never was a PAL Nintendo S-Video cable (I have checked every European eBay site for one) what do you think the components would/should have been on the Chroma and Luma lines? - I have read so much conflicting advice on this. I am guessing there should have been a 75ohm resistor and 220uf capacitor on one of the lines, like the PAL Composite cable, but I still dont know which line this should be to make the signal 'normal'.

Also, I am curious to know why these extra compoents (75ohm resistor and 220uf Capacitor) are even neccessary on PAL Nintendo AV cables? - I had read somewhere that it was due to the 50/60hz difference also affecting the brightness levels - is this true/correct?
« Last Edit: July 20, 2008, 09:31:57 AM by Link83 »

Offline viletim

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Ah, the Gamecube too. Can you check if there's a 75 ohm resistor somewhere on the composite line? Measure resistance between ground and each end of coupling capacitor in turn.

No rush on the "in TV" measurements for the SNES SCART cable, whenever you get a chance.

Quote
if I wanted to re-create the Official PAL SNES scart cable, could I do it on a third-party Gamecube cable by removing the capacitors and putting 75 ohm resistors in there place? - or do the resistors have to be connected to ground/be a resistor network?

Nah, they must be in parallel for the same operation.

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 don't know about the Y/C lines, I'll look into it though... It's very important to get the signal level of composite video/S-video right. It's because you have two parts, the chroma which is frequency modulated (the ammount of colour you get doesn't change with the amplitude of the signal) and luma (contrast is directly proportional to amplitude of the signal). If the luma/composite signal is too big you will get a washed out picture, if it's too small you get oversaturated colours.

The parts in the cables are no less important that the parts in the units. In fact, they would be better off in the units to begin with. I really have no idea why stuffing parts into the SCART cables is so popular...Maybe it makes the unit smaller. :)

BTW - My holidays are over, it may take a few days for me to reply to further questions.


Offline viletim

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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.

I tried to update my website, but I failed. Now there's no diagram for the PAL SNES at all. I've uploaded the new diagram to:
http://morpheus.webcity.com.au/~who49188/gamescart/
And I suppose I'll have to move the rest of the site over too at some point.

Link83,
Quote
Ah, the Gamecube too. Can you check if there's a 75 ohm resistor somewhere on the composite line? Measure resistance between ground and each end of coupling capacitor in turn.
Could you check this? I think I've got an extra resistor in my diagram that shouldn't be there.



Online Link83

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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..

So my 1995 SNES does have different components?

The Official PAL SNES Scart cable works perfectly with my 1995 SNES too, but then so does the Official Gamecube Scart cable! I am hoping to get hold of an earlier revision SNES soon (Hopefully a 1992 version) as this 1995 revision SNES cannot be modified for 50/60hz  :( When I buy it I will test both Official cables with it and update this thread on the results  :)

Also, if your interested I came across this German forum thread about PAL SNES console revisions, which does have some pictures of the different motherboards and may help determine when the 'change' was made (Translated by Google):-
http://translate.google.co.uk/translate?hl=en&sl=de&u=http://www.project-casemod.de/modules/newbb/viewtopic.php%3Ftopic_id%3D835%26forum%3D25%26post_id%3D13143&sa=X&oi=translate&resnum=1&ct=result&prev=/search%3Fq%3DSNSP-CPU-1CHIP-01%26hl%3Den

I like your new circuit diagram for the PAL SNES Scart cable, but it is still quite different to the Official cable - is this intentional?

Also, now that we know that Nintendo wanted the 'Vpp' to be 0.77 for the PAL SNES, does that mean that 33ohm resistors would be better suited than 47ohm resistors if we wanted to make our own PAL SNES Scart cables? (As the Vpp would then be 0.76 rather than 0.69) [Would also still love to know how you measure 'Vpp']

Sorry about your problems updating your site  :(

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Link83,
Quote
Ah, the Gamecube too. Can you check if there's a 75 ohm resistor somewhere on the composite line? Measure resistance between ground and each end of coupling capacitor in turn.
Could you check this? I think I've got an extra resistor in my diagram that shouldn't be there.

Sorry I didnt check this before  :-[ - the reason is because shortly after I took the pictures I modified that Official Gamecube cable so that I could use it with my RGB modded N64 by removing all the capacitors off the circuit board (Would have used an unofficial cable but I was desperate to test it right then ::))
I have some new Official Gamecube cables on the way, so I will be testing those for you as soon as they arrive. I am pretty sure however that there was no resistance on the Composite line - only a 220uf capacitor as you can see in the picture. The only resistor in the whole cable is the 100ohm one used on the +5v line.
However, I dont want to give you a 'definite' answer until I have tested the new cables, which are in the post - I hope you understand.

I have been wondering for quite a whiole now - why do so many people recommend putting a 75ohm resistor between Scart pins 18 and 20? There isnt one on the Official cable, as Pin 18 is not even present!

Also, in the official cables both Grounds (Multi AV Out Pins 5 & 6) are joined together and connect to Scart Pin 17, but in your diagrams they connect to many different Scart pins - why is this? Is this just the 'recommended' way a Scart cable should be wired? I am just curious....
« Last Edit: July 27, 2008, 10:19:57 PM by Link83 »

Offline viletim

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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..

So my 1995 SNES does have different components on the RGB lines?

It's video driver circuit is different, yes. It's normal for bits of the circuit to change through board revisions. It's possible (infact likely) that 47 ohm series resistors (my original PAL SNES diagram) will behave differently with the different internal circuit. The official cable with parallel 75 ohm resistors should work fine with both.
Quote
The Official PAL SNES Scart cable works perfectly with my 1995 SNES too, but then so does the Official Gamecube Scart cable. I am hoping to get hold of an earlier revision SNES soon (Hopefully 1992 version) as this 1995 revision SNES cannot be modified for 50/60hz  :( When I buy it I will test both cables with this earlier SNES and update this thread on the results  :)
I can confirm that 75 ohm parallel resistors on the RGB lines works well for the 1992 model PAL SNES.
Quote
Link83,
Quote
Ah, the Gamecube too. Can you check if there's a 75 ohm resistor somewhere on the composite line? Measure resistance between ground and each end of coupling capacitor in turn.
Could you check this? I think I've got an extra resistor in my diagram that shouldn't be there.

Sorry I didnt check this before  :-[ - the reason is because shortly after I took the pictures I modified that Official Gamecube cable so that I could use it with my RGB modded N64 by removing all the capacitors off the circuit board (Would have used an unofficial cable but I was desperate to test it right then)
I have some new official Gamecube cables on the way, so I will be testing those for you as soon as they arrive. I am pretty sure however that there was no resistance on the Composite line - only a 220uf capacitor as you can see in the picture. The only resistor in the whole cable is the 100ohm one used on the +5v line.
However, I didnt want to give you a 'definite' answer until I had tested the new cables which are in the post - hope you understand.
Quote
That's fine, I'm in no hurry.
I have been wondering for quite a whiole now - why do so many people recommend putting a 75 ohm resistor between Scart pins 18 and 20? There isnt one on the Official cable as Pin 18 is not even present!
18 is ground, 20 is video out. This resistor is present on every signle PAL SNES composite cable, and it's inside your SNES SCART cable. If you leave it out you will have a distorted picture. I want to stress that this only applies to the PAL SNES, and maybe the PAL Gamecube (pending your tests).
Quote
Also, in the official cables both Grounds (Multi AV Out Pins 6 & 7) are joined together and connect to Scart Pin 17, but in your diagrams they connect to many different Scart pins - why is this? Is this just the 'recommended' way a Scart cable should be wired? I am just curious....

I'm not really interested in documenting every paltry detail of the various SCART cables. I don't care how the ground is wired, so long as it is wired. I draw all the diagrams with one ground connected at the the console end and all grounds connected at the SCART end. The reverse is probably more like the way they are actually wired, but I draw it this way because: 1. Connecting all the grounds together at the console end makes the diagram look messy 2. It highlights the fact that a SCART socket has multiple ground connections, there is no "best one".

Also, I always use a 180 ohm resistor between +5v (if it exists) and the RGB status pin 16. For no better reason than I like it like that. Any resistor from 100 to 200 ohms would also be suitable, though.

Offline RGB32E

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Here is the SHVC-010 PCB underside:

Offline RGB32E

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And here are angled pictures of the top side

Online Link83

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Ah, the Gamecube too. Can you check if there's a 75 ohm resistor somewhere on the composite line? Measure resistance between ground and each end of coupling capacitor in turn

Could you check this? I think I've got an extra resistor in my diagram that shouldn't be there.
I am so sorry for taking so long to get back to you on this - my new Official Gamecube Scart Cables just arrived a week ago (Took alot longer to arrive than I thought they would)

Anyway, having tested a totally unmodified cable I can confirm that there is indeed a 75ohm resistor between Composite and Ground on the Official Gamecube Scart cable. I was very surprised at this, as it isnt on the little PCB. Also, I didnt notice it before in my previous 'testing' because I was connecting the probes after the Capacitors, not before them, Doh! ::)

Having taken apart the MultiAV plug end though I can see that the resistor is there, covered in heat shink tubing. Its also covered up by a piece of black sticky fabric - so its abit hard to see normally. Heres some pics with the fabric peeled away, making the resistor alot more obvious:-


Funny thing is though that the Official Gamecube Scart Cable doesnt use Pin 18 for Ground - it uses Pin 17 for Ground instead! Isnt that incorrect for the 'proper way' or wiring a Scart cable? Ground is the Grey wire in this pic:-


So the Composite line has a 75ohm resistor connected to ground, and a 220uf capacitor on it, just like the Official PAL AV Cables.

RGB32E - Just wanted to say a big thank you for those pictures  ;D They are really interesting - its kind of strange how 'basic' looking the PCB is on the SVHC-010 compared to Nintendo's European Scart cables.

Offline viletim

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Anyway, having tested a totally unmodified cable I can confirm that there is indeed a 75ohm resistor between Composite and Ground on the Official Gamecube Scart cable. I was very surprised at this, as it isnt on the little PCB. Also, I didnt notice it before in my previous 'testing' because I was connecting the probes after the Capacitors, not before them, Doh! ::)
Thanks for the confirmation. It seems my diagram is correct after all.

Quote


Funny thing is though that the Official Gamecube Scart Cable doesnt use Pin 18 for Ground - it uses Pin 17 for Ground instead! Isnt that incorrect for the 'proper way' or wiring a Scart cable? Ground is the Grey wire in this pic:-

It doesn't matter, both pins are connected to ground in all TVs.

Quote
So the Composite line has a 75ohm resistor connected to ground, and a 220uf capacitor on it, just like the Official PAL AV Cables.
At least they're consistant...

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