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Making a JP/US Saturn work with an EU scart cable

Started by KillingBeans, September 30, 2010, 10:24:56 pm

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KillingBeans

September 30, 2010, 10:24:56 pm Last Edit: June 11, 2018, 05:46:52 am by KillingBeans
I made a small post about this in the 'GameSX.com General' section, and have since come up with a little fix. Here's a copy/paste of the tread I made about it on Sega-16.com -->>>

I found out that there's a small difference between the AV pinout on an EU Saturn and the pinout on an NTSC Saturn (Japanese or American). On the EU models, pin 1 on the AV socket is 9 volt DC. But it's Sync on the NTSC models. That's why the picture flickers or does other strange things when you try to use the EU scart cable with a JP or US Saturn.



Here's a simple mod to make a Japanese or American Saturn work properly with an EU scart cable:




Remove one of the black thingies (a decoupling capacitor?) in order to disconnect the Sync line and get a good solder point at the same time.



Connect pin 1 to the 9v DC point on the transistor, and voila! Now the Saturn works perfectly with the scart cable :)

EDIT: The component that I'm calling a "transistor" is actually a diode. SMD components are so freaky :D

viletim

October 01, 2010, 12:50:17 am #1 Last Edit: October 01, 2010, 12:57:08 am by viletim
Pin 1 is unused on an official Saturn SCART cable. Here's a wiring diagram of how it should be connected:
http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm#saturn

EDIT: I just checked my cable (official) and pin 1 of the DIN-10 is actually used for the switching voltage at SCART pin 8. I'll update my diagram in the near future. You should check your cable with a multimeter, it probably just has a couple of wires swapped around.

KillingBeans

October 01, 2010, 02:32:27 am #2 Last Edit: October 01, 2010, 05:56:11 am by KillingBeans
Quote from: viletim on October 01, 2010, 12:50:17 am
EDIT: I just checked my cable (official) and pin 1 of the DIN-10 is actually used for the switching voltage at SCART pin 8. I'll update my diagram in the near future.


Exactly. When using an EU RGB cable on an EU Saturn, the 9v DC from pin 1 on the AV socket is led directly to pin 8 on the scart and sets the TV to 4:3 mode (the correct aspect ratio for a Saturn!!). Of course the 9v DC is also being voltage devided by a resistor to get RGB mode on the scart pin 16. When using the EU RGB cable on a non EU Saturn, pin 1 on the AV socket is Composite Sync, and so the TV gets this small voltage alternating signal instead of the DC voltage needed for the switching. Most TVs dont know what the f¤#k to do in this situation, and just do weird things. My small mod is a fix for this.

Quote from: viletim on October 01, 2010, 12:50:17 am
You should check your cable with a multimeter, it probably just has a couple of wires swapped around.


What? Why? That makes no sense...

viletim

Quote from: KillingBeans on October 01, 2010, 02:32:27 am
What? Why? That makes no sense...


Never mind, I didn't read the original message properly.

Good work with the mod.

KillingBeans


Darklegion

Hmm, maybe the wavy sync I was getting with my Saturn + XRGB-2 is related? I may try this, that issue was really annoying.

NFG


Link83

April 13, 2011, 08:54:39 am #7 Last Edit: April 13, 2011, 10:15:46 pm by Link83
Bumping this thread as I am a little confused. I have just been looking at the official Sega Saturn schematics for the VA13 motherboard released by l_oliveira here:-
http://www.assemblergames.com/forums/showthread.php?t=27654
On the pdf entitled "Conjunto PCI VA 13_09" it gives the pinout for the Saturn AV Connector, and it says Pin 1 is VCC and Pin 4 is C-Sync ??? Here is a small section showing the AV connector pinout:-

Apart from Pin 1 and Pin 4 all the other pins match the signals listed on the wiki diagram. This schematic is from the Brazillian Tec Toy Saturn so i'm not sure if its NTSC or PAL, but if its correct then either way the pinout in the wiki would be wrong.

I dont have a Saturn available to check, but is Pin 1 or Pin 4 C-Sync? and which pin is 5V and/or 9V?
Perhaps Pin 1 is VCC in all regions, but on a PAL Saturn its 9V and on a NTSC Saturn its 5V? That might cause switching problems since the resistor used in the PAL Scart cable would to incorrect for an NTSC Saturn?
Or maybe its like this:-
NTSC
Pin 1 - C-Sync
Pin 4 - 5V
PAL
Pin 1 - 9V
Pin 4 - C-Sync
Doesn't seem to make a lot of sense to swap it like that though?

bigsanta

April 20, 2011, 06:44:57 am #8 Last Edit: April 20, 2011, 11:00:00 pm by bigsanta
Here's my modded white jap saturn .A VA11 model ,which ,as you can see,things are a little different ,but just as easy to mod pin 1 of the av .



















zyrobs

Quote from: Link83 on April 13, 2011, 08:54:39 am
On the pdf entitled "Conjunto PCI VA 13_09" it gives the pinout for the Saturn AV Connector, and it says Pin 1 is VCC and Pin 4 is C-Sync ??? Here is a small section showing the AV connector pinout:-

Apart from Pin 1 and Pin 4 all the other pins match the signals listed on the wiki diagram. This schematic is from the Brazillian Tec Toy Saturn so i'm not sure if its NTSC or PAL, but if its correct then either way the pinout in the wiki would be wrong.

I dont have a Saturn available to check, but is Pin 1 or Pin 4 C-Sync? and which pin is 5V and/or 9V?
Perhaps Pin 1 is VCC in all regions, but on a PAL Saturn its 9V and on a NTSC Saturn its 5V? That might cause switching problems since the resistor used in the PAL Scart cable would to incorrect for an NTSC Saturn?
Or maybe its like this:-
NTSC
Pin 1 - C-Sync
Pin 4 - 5V
PAL
Pin 1 - 9V
Pin 4 - C-Sync
Doesn't seem to make a lot of sense to swap it like that though?


There is a very simple explanation for that: the order shown in those specs does not match the one that the pinout graph uses. Pin 4 (on the mini-din AV out) is always +5vdc on all saturns I know of, while pin 1 is composite sync on what seems like every Saturn except PAL models, where pin 1 is +9vdc. If you'd put that on a schematic, it would mean that TP4 is not connected to CN5 (its place on CN5 being taken up by a +9vdc line).

Link83

May 11, 2011, 11:50:04 am #10 Last Edit: May 11, 2011, 12:03:29 pm by Link83
Quote from: zyrobs on May 11, 2011, 07:56:56 am
There is a very simple explanation for that: the order shown in those specs does not match the one that the pinout graph uses. Pin 4 (on the mini-din AV out) is always +5vdc on all saturns I know of, while pin 1 is composite sync on what seems like every Saturn except PAL models, where pin 1 is +9vdc. If you'd put that on a schematic, it would mean that TP4 is not connected to CN5 (its place on CN5 being taken up by a +9vdc line).

Sorry but that doesnt make sense ??? The DIN socket is numbered using a standard pinout, and all the other pins match.

Quote from: bigsanta on April 20, 2011, 06:44:57 am
Here's my modded white jap saturn .A VA11 model ,which ,as you can see,things are a little different ,but just as easy to mod pin 1 of the av .

On a VA11 does EM4 connect to Pin 1 or Pin 4 of the AV socket? Also did you check what the output was of Pin 1 and Pin 4 before modding? I only ask as I am beginning to think that either the schematic is wrong, or that perhaps Sega actually did mess up the AV pinout on later motherboard revisions (The schematic is of a VA13) Especially since I read this:-
http://www.ntsc-uk.co.uk/showthread.php?18412-Saturn-RGB-scart-problem....&p=1152303&highlight=#post1152303
Quote from: gcjaeI ordered an RGB scart cable for my white JP Saturn last year from www.ravenonline.co.uk and the site said that it was for both grey and white models. When it arrived it didn't work. I tested it on a pal machine to make sure they hadn't sent a UK one and it didn't work on that either.

I called them and spoke to Jason who told me that very late model white consoles were wired slightly differently. He said he would have to get his engineer to make one up for me. I sent it back and about 3 weeks later got a replacement that worked just fine.


If anyone has a White JPN Saturn (Or a Tec Toy model) which has a VA13 motherboard, it might be worth investigating...

bigsanta

May 12, 2011, 01:12:10 am #11 Last Edit: May 13, 2011, 10:03:18 am by bigsanta
JP saturn -Va 11 board -EM4 goes to pin 1 of the saturn's din socket (CSYNC)!

bigsanta

May 12, 2011, 01:20:00 am #12 Last Edit: September 21, 2011, 11:24:47 pm by bigsanta
Quote from: zyrobs on May 11, 2011, 07:56:56 am
Quote from: Link83 on April 13, 2011, 08:54:39 am
On the pdf entitled "Conjunto PCI VA 13_09" it gives the pinout for the Saturn AV Connector, and it says Pin 1 is VCC and Pin 4 is C-Sync ??? Here is a small section showing the AV connector pinout:-

Apart from Pin 1 and Pin 4 all the other pins match the signals listed on the wiki diagram. This schematic is from the Brazillian Tec Toy Saturn so i'm not sure if its NTSC or PAL, but if its correct then either way the pinout in the wiki would be wrong.

I dont have a Saturn available to check, but is Pin 1 or Pin 4 C-Sync? and which pin is 5V and/or 9V?
Perhaps Pin 1 is VCC in all regions, but on a PAL Saturn its 9V and on a NTSC Saturn its 5V? That might cause switching problems since the resistor used in the PAL Scart cable would to incorrect for an NTSC Saturn?
Or maybe its like this:-
NTSC

CN5 is just the name for Connector 5 ,the din socket !CN 6 is the communication connector and CN1  is the cart port .
Pin 1 - C-Sync
Pin 4 - 5V
PAL
Pin 1 - 9V
Pin 4 - C-Sync
Doesn't seem to make a lot of sense to swap it like that though?


There is a very simple explanation for that: the order shown in those specs does not match the one that the pinout graph uses. Pin 4 (on the mini-din AV out) is always +5vdc on all saturns I know of, while pin 1 is composite sync on what seems like every Saturn except PAL models, where pin 1 is +9vdc. If you'd put that on a schematic, it would mean that TP4 is not connected to CN5 (its place on CN5 being taken up by a +9vdc line).

CN5 is just the name for the din socket,not a pin !CN6  is the communication port and CN1 is the cart port(CN=connector/connection !?)

zyrobs

Quote from: Link83 on May 11, 2011, 11:50:04 am
Sorry but that doesnt make sense ??? The DIN socket is numbered using a standard pinout, and all the other pins match.


Well then either the specs are fucked or the brazilian models really did swap pin 1 and 4. I guess its just the specs being wrong (about c-sync, anyway), because it would give a faint reason as to why the official Sega UK RGB cables got the +dc signal from pin 1.

I own 3 different PAL Saturns (VA0, VA, VA9), and pin1 is +9vdc on all of them, while pin4 is +5vdc and c-sync is not connected to the mini-din at all.

antron

September 13, 2011, 01:27:57 am #14 Last Edit: September 13, 2011, 01:31:14 am by antron
I've seen at least two saturn SCART cables that had Pin 1 tied to pin 16 of the SCART connector.

I always wondered what that was about, but it made it so much easier to connect my US Saturn to JAMMA.

ameisenmann

December 05, 2011, 06:02:40 pm #15 Last Edit: December 05, 2011, 06:10:32 pm by ameisenmann
I made a scart-to-scart-solution on my PAL Saturn with VA9 board.
http://segasaturngroup.proboards.com/index.cgi?board=hardware&action=display&thread=5130

I learned that TP4 could not really give +5V because the TV always switched to scart mode and back to TV. It also gave me no stable RGB picture when I switched manually to scart channel. The picture always disappeared for a short time. After I took +5V from elsewhere on the board it worked fine!

So I think the specs of the brazilian Saturn match exactly my PAL Saturn.

tcancian

Hello everyone. I'm from Brazil and i'm the unlucky owner of two Saturns, a Model 2 Brazilian Saturn and a Model 1 American Saturn.

Both are regional encoded to NTSC.

Two months ago I purchased a SCART RGB for NTSC systems and my picture just got weird, but back then, I didn't knew about this Pin 1 and Pin 4 confusion and bought another one, I just got it today just to witness the exact same weird rainbow lines on the image. The cable works great on the american Model, but the flat cable is busted and the modchip stopped working years ago, so all that's left for me it's the Model 2. But on the Model 2, when I hook up the cable, I get rainbow effects, and weird sync issues all over the place. It's really, really annoying. And it shouldn't be there.

My theory is:

TecToy was merely a hardware assembler, and as such, assembled Saturns from whatever batch they could get from Sega. Probably they got an overstock batch from Europe, changed the bottom outercasing, the regional jumpers for NTSC game encoding and PAL-M video norm, and shipped the systems out, probably never expecting someone would actually use NTSC RGB cables. RF, Composite and S-Video all work OK on my system by the way.

Any tips on what should I do? If any of you could post what your image was like before the mod, it would be of great help. I'm also not inclined to buy a third SCART cable, so if there's any mod to make a PAL mutant NTSC-minded Saturn work with the NTSC SCART cable, please let me know.

When I desolder the modchip and get access to the motherboard, I'll upload pictures so that you may know which VA is it.

Please take into account that my setup is not native RGB, I use a transcoder I got from eBay, so i'm actually using Component Video on my TV.

If my cable hooks up Pin 1 (which COULD BE 9V if my Motherboard is European) to Pin 20 on SCART (where my transcoder picks up the Sync) should I even be getting a picture AT ALL? I'm so confused.   ??? ??? ???

viletim

tcancian,

There is no such thing as an NTSC SCART cable. SCART is a European standard and Sega only released one SCART cable.

With the aid of a Saturn SCART cable, the video output (pin 8 of the mini-DIN) is connected your colour converter's video input (pin 20 of the SCART). The sync/switching signal on pin 1 of the mini-DIN may be connected to the video switching signal on the SCART, but this won't be used at all by you converter box.

tcancian

I bought mine from retro-gaming-acessories and the description said RAW SYNC, so I'm assuming that it's a custom made cable in which Pin 1 is wired to Pin 20 instead of Pin 8, I've heard that C-Sync (which is present on NTSC models) is better than Composite Video for sync. The wierd thing is that my american Sega Saturn works perfect with the cable, whereas my brazilian Sega Saturn doens't (probably because it's euro-specs). :(.

KillingBeans

In that case, I guess you'll have to do the reversed procedure on the brazilian Saturn. Meaning that you'll have to disconnect the 9V from pin 1 and connect the pin to Sync.

Trygon

Hello, I will buy a EU Saturn and since I have a beautiful Sony Trinitron and I live in Europe (PAL) I'd like to use RGB. What about if I buy the official Saturn Japanese 21 pin RGB cable and I modify the pin solderings to make it a Euro Scart. Will it work? Thanks!

KillingBeans

June 11, 2018, 05:53:27 am #21 Last Edit: June 11, 2018, 06:02:33 am by KillingBeans
It would maybe work, yes. Depends on whether the Japanese cable uses raw sync or composite video for timing. Don't really know the answer for that. But there's no need to modify a JP-21 cable. EU SCART RGB cables for the Saturn are very common  :)

Trygon

June 11, 2018, 07:09:28 pm #22 Last Edit: June 11, 2018, 07:15:00 pm by Trygon
Quote from: KillingBeans on June 11, 2018, 05:53:27 am
It would maybe work, yes. Depends on whether the Japanese cable uses raw sync or composite video for timing. Don't really know the answer for that. But there's no need to modify a JP-21 cable. EU SCART RGB cables for the Saturn are very common  :)


Yes, but I do not always trust third party EU scart cables because I think they are not always quality cables and they can show blurry video and buzz audio. How do I recognise a good cable (besides that thing of 75 Ohm). And what's the difference between raw syncing and composite video timing? Thanks!

EDIT: RAW Sync is the C-Sync, right? I don't think it is widely used...

Trygon

And in case, what do you think is better worth buying among Sync-on-LUMA, Sync over composite video and CSYNC?

Sorry for bothering, I just want to learn. Thanks again

KillingBeans

Quote from: Trygon on June 11, 2018, 07:09:28 pm
Yes, but I do not always trust third party EU scart cables because I think they are not always quality cables and they can show blurry video and buzz audio.


I have an original Megadrive II SCART RGB cable, and it's really crappy. It exhibits both of those problems heavily. Maybe because it's using a shitty step-up converter for AV switching, or maybe the electrolytic capacitors have just died.. Haven't bothered replacing them  :-\

Just to let you know that original is not always best  ;)

Quote from: Trygon on June 11, 2018, 07:09:28 pm
How do I recognise a good cable (besides that thing of 75 Ohm).


I sold all of my Saturn stuff a few years ago, so my expertise on the subject is not what it used to be. 75Ohm resistors for impedance matching and some capacitors at a few hundred microfarad for AC coupling on the color lines probably won't hurt. To be honest I've never build a Saturn SCART cable. Most of the EU Saturns I bought years ago already had a perfectly good SCART RGB cable bundled, and I just used those.

In theory you'd have to be a complete muppet to mess up a Saturn SCART RGB cable. To get a reasonable result all that would be required would be a 100Ohm resistor between 5V and the blanking/RGB-switch pin, and then just connecting the dots. I wouldn't worry too much about the quality of third party cables  :)

Quote from: Trygon on June 11, 2018, 07:35:00 pm
And in case, what do you think is better worth buying among Sync-on-LUMA, Sync over composite video and CSYNC?


C-sync is preferable, assuming that it has the correct amplitude and doesn't need buffering. Don't know if that's the case on the Saturn?

Sync-on-Luma is the second best option. I've never used it, so I can't really comment any further on its use or quality.

Composite Video is the "worst" option, but it's guaranteed to work, and I'd argue that CRT TV sets does such good job at extracting C-sync from the signal, that you'd be hard-pressed to tell a difference between the three methods.

Trygon